Hi Dan,

Thanks for the updates.  A few more comments.

Your readme states that adding -dramfs to the end of a target will enable
the support, but there is no logic yet added here to the top-level
configure.ac to specify building in dramfs directory.   Libgloss has
recently been cleaned up to move all configuration into the top-level
libgloss directory (none of the targets have their own
configure.in/configure.ac).  The way it is now, building libgloss/dramfs
would have to be done manually in the dramfs directory.

There is a comment mentioning risc-v and configure.ac in your configure.in
file.

Regards,

-- Jeff J.

On Wed, Aug 9, 2023 at 6:22 PM Dan Petrisko <petrisko@cs.washington.edu>
wrote:

> Co-authored-by: Bandhav Veluri <bandhav.veluri00@gmail.com>
> Co-authored-by: farzamgl <farzamgl@uw.edu>
> Co-authored-by: taylor-bsg <taylor-bsg@users.noreply.github.com>
> ---
>  .gitmodules                        |   0
>  COPYING.LIBGLOSS                   |  27 +++++
>  libgloss/dramfs/Makefile.in        | 230
> +++++++++++++++++++++++++++++++++++++
>  libgloss/dramfs/README.md          | 158 +++++++++++++++++++++++++
>  libgloss/dramfs/configure.in       |  45 ++++++++
>  libgloss/dramfs/crt0.S             |  44 +++++++
>  libgloss/dramfs/sys_close.c        |  41 +++++++
>  libgloss/dramfs/sys_execve.c       |  40 +++++++
>  libgloss/dramfs/sys_exit.c         |  41 +++++++
>  libgloss/dramfs/sys_fork.c         |  39 +++++++
>  libgloss/dramfs/sys_fstat.c        |  48 ++++++++
>  libgloss/dramfs/sys_getpid.c       |  36 ++++++
>  libgloss/dramfs/sys_gettimeofday.c |  40 +++++++
>  libgloss/dramfs/sys_isatty.c       |  36 ++++++
>  libgloss/dramfs/sys_kill.c         |  40 +++++++
>  libgloss/dramfs/sys_link.c         |  38 ++++++
>  libgloss/dramfs/sys_lseek.c        |  44 +++++++
>  libgloss/dramfs/sys_open.c         |  64 +++++++++++
>  libgloss/dramfs/sys_read.c         |  67 +++++++++++
>  libgloss/dramfs/sys_sbrk.c         |  49 ++++++++
>  libgloss/dramfs/sys_stat.c         |  50 ++++++++
>  libgloss/dramfs/sys_times.c        |  35 ++++++
>  libgloss/dramfs/sys_unlink.c       |  39 +++++++
>  libgloss/dramfs/sys_wait.c         |  39 +++++++
>  libgloss/dramfs/sys_write.c        |  52 +++++++++
>  25 files changed, 1342 insertions(+)
>  create mode 100644 .gitmodules
>  create mode 100644 libgloss/dramfs/Makefile.in
>  create mode 100644 libgloss/dramfs/README.md
>  create mode 100644 libgloss/dramfs/configure.in
>  create mode 100644 libgloss/dramfs/crt0.S
>  create mode 100644 libgloss/dramfs/sys_close.c
>  create mode 100644 libgloss/dramfs/sys_execve.c
>  create mode 100644 libgloss/dramfs/sys_exit.c
>  create mode 100644 libgloss/dramfs/sys_fork.c
>  create mode 100644 libgloss/dramfs/sys_fstat.c
>  create mode 100644 libgloss/dramfs/sys_getpid.c
>  create mode 100644 libgloss/dramfs/sys_gettimeofday.c
>  create mode 100644 libgloss/dramfs/sys_isatty.c
>  create mode 100644 libgloss/dramfs/sys_kill.c
>  create mode 100644 libgloss/dramfs/sys_link.c
>  create mode 100644 libgloss/dramfs/sys_lseek.c
>  create mode 100644 libgloss/dramfs/sys_open.c
>  create mode 100644 libgloss/dramfs/sys_read.c
>  create mode 100644 libgloss/dramfs/sys_sbrk.c
>  create mode 100644 libgloss/dramfs/sys_stat.c
>  create mode 100644 libgloss/dramfs/sys_times.c
>  create mode 100644 libgloss/dramfs/sys_unlink.c
>  create mode 100644 libgloss/dramfs/sys_wait.c
>  create mode 100644 libgloss/dramfs/sys_write.c
>
> diff --git a/.gitmodules b/.gitmodules
> new file mode 100644
> index 000000000..e69de29bb
> diff --git a/COPYING.LIBGLOSS b/COPYING.LIBGLOSS
> index c7a4c2924..0b30092a2 100644
> --- a/COPYING.LIBGLOSS
> +++ b/COPYING.LIBGLOSS
> @@ -425,3 +425,30 @@ CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
> NEGLIGENCE OR OTHERWISE)
>  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
>  POSSIBILITY OF SUCH DAMAGE.
>
> +(21) - University of Washington (*-*-*-dramfs targets)
> +
> +Copyright (c) 2023, University of Washington
> +All rights reserved.
> +
> +Redistribution and use in source and binary forms, with or without
> +modification, are permitted provided that the following conditions are
> met:
> +    * Redistributions of source code must retain the above copyright
> +      notice, this list of conditions and the following disclaimer.
> +    * Redistributions in binary form must reproduce the above copyright
> +      notice, this list of conditions and the following disclaimer in the
> +      documentation and/or other materials provided with the distribution.
> +    * Neither the name of the University of Washington nor the
> +      names of its contributors may be used to endorse or promote products
> +      derived from this software without specific prior written
> permission.
> +
> +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
> IS" AND
> +ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> +WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> +DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR ANY
> +DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
> +(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> +LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
> AND
> +ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
> THIS
> +SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> +
> diff --git a/libgloss/dramfs/Makefile.in b/libgloss/dramfs/Makefile.in
> new file mode 100644
> index 000000000..4d3d5013e
> --- /dev/null
> +++ b/libgloss/dramfs/Makefile.in
> @@ -0,0 +1,230 @@
> +#-------------------------------------------------------------------------
> +# Source files
> +#-------------------------------------------------------------------------
> +gloss_srcs = \
> +       sys_close.c \
> +       sys_execve.c \
> +       sys_exit.c \
> +       sys_fork.c \
> +       sys_fstat.c \
> +       sys_getpid.c \
> +       sys_gettimeofday.c \
> +       sys_isatty.c \
> +       sys_kill.c \
> +       sys_link.c \
> +       sys_lseek.c \
> +       sys_open.c \
> +       sys_read.c \
> +       sys_sbrk.c \
> +       sys_stat.c \
> +       sys_times.c \
> +       sys_unlink.c \
> +       sys_wait.c \
> +       sys_write.c
> +
> +# Extra files
> +
> +crt0_asm      = crt0.S
> +
> +# Multilib support variables.
> +# TOP is used instead of MULTI{BUILD,SRC}TOP.
> +
> +MULTIDIRS =
> +MULTISUBDIR =
> +MULTIDO = true
> +MULTICLEAN = true
> +
> +#-------------------------------------------------------------------------
> +# Basic setup
> +#-------------------------------------------------------------------------
> +
> +# Remove all default implicit rules since they can cause subtle bugs
> +# and they just make things run slower
> +
> +.SUFFIXES:
> +% : %,v
> +% : RCS/%,v
> +% : RCS/%
> +% : s.%
> +% : SCCS/s.%
> +
> +# Default is to build the prereqs of the all target (defined at bottom)
> +
> +default : all
> +.PHONY : default
> +
> +# Source directory
> +
> +obj_dir := .
> +src_dir := @srcdir@
> +VPATH   := $(src_dir) $(src_dir)/machine
> +
> +# Installation directories
> +
> +prefix  := @prefix@
> +DESTDIR ?= $(prefix)
> +
> +install_hdrs_dir := $(DESTDIR)$(prefix)/$(target_alias)/include/machine
> +install_libs_dir  = $(DESTDIR)$(prefix)/$(target_alias)/lib${MULTISUBDIR}
> +install_bins_dir := $(DESTDIR)$(prefix)/$(target_alias)/bin
> +
> +#-------------------------------------------------------------------------
> +# Programs and flags
> +#-------------------------------------------------------------------------
> +
> +# C compiler
> +
> +CC            := @CC@
> +CFLAGS        := @CFLAGS@
> +CFLAGS        += -mcmodel=medany
> +CPPFLAGS      := -I$(obj_dir) -I$(src_dir) $(dramfs_incs) -mcmodel=medany
> +COMPILE       := $(CC) -MMD -MP $(CPPFLAGS) $(CFLAGS)
> +
> +# Library creation
> +
> +AR            := @AR@
> +RANLIB        := @RANLIB@
> +
> +# Installation
> +
> +INSTALL       := @INSTALL@
> +INSTALL_DATA  := @INSTALL_DATA@
> +
> +#-------------------------------------------------------------------------
> +# Build Object Files from C Source
> +#-------------------------------------------------------------------------
> +
> +gloss_c_srcs = $(filter %.c, $(gloss_srcs))
> +gloss_c_objs = $(patsubst %.c, %.o, $(notdir $(gloss_c_srcs)))
> +gloss_c_deps = $(patsubst %.c, %.d, $(notdir $(gloss_c_srcs)))
> +
> +$(gloss_c_objs) : %.o : %.c
> +       $(COMPILE) -c $<
> +
> +gloss_objs += $(gloss_c_objs)
> +deps += $(gloss_c_deps)
> +junk += $(gloss_c_deps) $(gloss_c_objs)
> +
> +#-------------------------------------------------------------------------
> +# Build Object Files from Assembly Source
> +#-------------------------------------------------------------------------
> +
> +gloss_asm_srcs = $(filter %.S, $(gloss_srcs))
> +gloss_asm_objs = $(patsubst %.S, %.o, $(notdir $(gloss_asm_srcs)))
> +gloss_asm_deps = $(patsubst %.S, %.d, $(notdir $(gloss_asm_srcs)))
> +
> +$(gloss_asm_objs) : %.o : %.S
> +       $(COMPILE) -c -o $@ $<
> +
> +gloss_objs += $(gloss_asm_objs)
> +deps += $(gloss_asm_deps)
> +junk += $(gloss_asm_deps) $(gloss_asm_objs)
> +
> +#-------------------------------------------------------------------------
> +# Build libgloss.a
> +#-------------------------------------------------------------------------
> +
> +gloss_lib  = libgloss.a
> +$(gloss_lib) : $(gloss_objs)
> +       $(AR) rcv $@ $^
> +       $(RANLIB) $@
> +
> +junk += $(gloss_lib)
> +
> +install_hdrs += $(gloss_hdrs)
> +install_libs += $(gloss_lib)
> +install_specs += $(gloss_specs)
> +install_bins += $(gloss_bins)
> +
> +#-------------------------------------------------------------------------
> +# Build crt0.o
> +#-------------------------------------------------------------------------
> +
> +crt0_obj  = $(patsubst %.S, %.o, $(crt0_asm))
> +crt0_deps = $(patsubst %.S, %.d, $(crt0_asm))
> +
> +$(crt0_obj) : %.o : %.S
> +       $(COMPILE) -c $<
> +
> +deps += $(crt0_deps)
> +junk += $(crt0_deps) $(crt0_obj)
> +
> +install_libs += $(crt0_obj)
> +
> +#-------------------------------------------------------------------------
> +# Autodependency files
> +#-------------------------------------------------------------------------
> +
> +-include $(deps)
> +
> +deps : $(deps)
> +.PHONY : deps
> +
> +#-------------------------------------------------------------------------
> +# Installation
> +#-------------------------------------------------------------------------
> +
> +install_hdrs_wdir += $(addprefix $(src_dir)/, $(install_hdrs))
> +install-hdrs : $(install_hdrs_wdir)
> +       test -d $(install_hdrs_dir) || mkdir -p $(install_hdrs_dir)
> +       for file in $^; do \
> +               $(INSTALL_DATA) $$file $(install_hdrs_dir)/; \
> +       done
> +
> +install-libs : $(install_libs)
> +       test -d $(install_libs_dir) || mkdir -p $(install_libs_dir)
> +       for file in $^; do \
> +               $(INSTALL_DATA) $$file $(install_libs_dir)/$$file; \
> +       done
> +
> +install-specs : $(install_specs)
> +       test -d $(install_libs_dir) || mkdir -p $(install_libs_dir)
> +       for file in $^; do \
> +               $(INSTALL_DATA) $$file $(install_libs_dir)/; \
> +       done
> +
> +install-bins : $(install_bins)
> +       test -d $(install_bins_dir) || mkdir -p $(install_bins_dir)
> +       for file in $^; do \
> +               $(INSTALL) $$file $(install_bins_dir)/; \
> +       done
> +
> +install : install-hdrs install-libs install-specs install-bins
> +.PHONY : install install-hdrs install-libs
> +
> +#-------------------------------------------------------------------------
> +# Regenerate configure information
> +#-------------------------------------------------------------------------
> +
> +configure_prereq = \
> +  $(src_dir)/configure.in \
> +
> +$(src_dir)/configure : $(configure_prereq)
> +       cd $(src_dir) && autoconf
> +
> +config.status : $(src_dir)/configure
> +       ./config.status --recheck
> +
> +Makefile : $(src_dir)/Makefile.in config.status
> +       ./config.status
> +
> +dist_junk += config.status Makefile config.log
> +
> +#-------------------------------------------------------------------------
> +# Default
> +#-------------------------------------------------------------------------
> +
> +all : $(install_libs) $(install_bins)
> +.PHONY : all
> +
> +#-------------------------------------------------------------------------
> +# Clean up junk
> +#-------------------------------------------------------------------------
> +
> +clean :
> +       rm -rf *~ \#* $(junk)
> +
> +distclean :
> +       rm -rf *~ \#* $(junk) $(dist_junk)
> +
> +.PHONY : clean distclean
> diff --git a/libgloss/dramfs/README.md b/libgloss/dramfs/README.md
> new file mode 100644
> index 000000000..09b92b1a1
> --- /dev/null
> +++ b/libgloss/dramfs/README.md
> @@ -0,0 +1,158 @@
> +# Newlib/DRAMFS
> +###### Bandhav Veluri and Michael Taylor, Bespoke Silicon Group UW
> +
> +Note: Mirror changes to this file to
> https://github.com/bespoke-silicon-group/bsg_newlib_dramfs/blob/dramfs/README.md
> +
> +## Introduction
> +
> +Newlib is a light-weight C standard library implementation for embedded
> systems. It elegantly separates system specific functionality (system
> calls) into an easily portable portion called Libgloss. Libgloss contains
> system call implementations for different architectures/systems in it.
> Porting Newlib to an architecture/system essentially involves porting these
> system call implementations in Libgloss. Complete guide for porting Newlib
> can be found in [5].
> +
> +Running POSIX programs on bare metal systems require some sort of
> implementation for file i/o and malloc. Malloc depends on just one
> system-call called sbrk, which essentially increments or decrements heap
> pointer as and when requested. Whereas, file i/o requires an actual file
> system, or an interface that can mimic a file system. This Newlib port uses
> an open-source lightweight file-system designed for embedded flash file
> systems by ARM called LittleFS (LFS). LittleFS also supports a DRAM-based
> file system, which is the one we use.
> +
> +The idea is to implement file i/o syscalls by simply translating them to
> LFS function calls, which in turn will operate on memory, rather than
> trying to use a more complex I/O emulation facility, like proxy kernels,
> that package up I/O calls and ship them over to a host. This allows for
> more reproducible I/O emulation, since the host is no longer an
> asynchronous process. It also eliminates the infrastructure pain caused by
> mapping these proxy-IO calls to different embodiments of the design --
> simulator, VCS, verilator, FPGA emulation, ASIC testboard, and PCI-e hosted
> chip.
> +
> +## Installation
> +
> +Newlib/Dramfs is intended to be a separate Board Support Package (BSP) in
> Newlib. Newlib can be configured to install this BSP by setting the target
> to end with `dramfs`:
> +
> +```
> +$ ./configure --target=<AnyArchiteture>-<AnyVendor>-<AnyString>dramfs
> [<other options>]
> +```
> +
> +Since this BSP works with any ISA, architecture field could be anything!
> +
> +## Porting
> +
> +Porting Newlib/Dramfs requires following four steps:
> +1. Implement `dramfs_exit(int)` (routine to exit the execution
> environment).
> +2. Implement `dramfs_sendchar(char)` (routine to output non-file I/O (for
> debugging etc)).
> +3. Implment C-runtime initiation including a call to `dramfs_fs_init()`
> in it.
> +4. Implement linker command script including definition of `_end` symbol
> (heap pointer) in it.
> +
> +#### 1, 2. Interfacing functions:
> +```
> +/*
> + * dramfs_intf.c
> + *
> + * Sample Implementation of Newlib/DRAMFS interface
> + */
> +
> +#include <stdlib.h>
> +#include <machine/dramfs_fs.h> // This header is installed with this BSP!
> +
> +void dramfs_exit(int exit_status) {
> +  if(exit_status == EXIT_SUCCESS) {
> +    // Exit the environment successfully
> +
> +    // Replace this with code to exit
> +    // successfully on your system.
> +  } else {
> +    // Exit the environment with failure
> +
> +    // Replace this with code to exit
> +    // with failure on your system.
> +  }
> +
> +  // do nothing until we exit
> +  while(1);
> +}
> +
> +void dramfs_sendchar(char ch) {
> +  // code to display ‘ch’
> +  // in many cases you may just want to have a memory
> +  // mapped I/O location that you write to
> +  // whether that is simulator magic, a NOC, a UART, or PCIe.
> +}
> +```
> +
> +#### 3. Adding `dramfs_fs_init` call to C-runtime initialization code:
> +
> +The function `dramfs_fs_init` (implemented in this BSP) has to called
> before calling the main. This step mounts the LittleFS image using a tiny
> block device driver implemeted by us. A sample C-runtime initialization is
> provided below:
> +
> +```
> +# Sample crt.S
> +#
> +# This is architecture specific; hence user would implement this code
> +# Following example is for a RISC-V system.
> +
> +.section .crtbegin,"a"
> +
> +.globl _start
> +_start:
> +
> +  # initialize global pointer
> +  la gp, _gp
> +
> +  # initialize stack pointer
> +  la sp, _sp
> +
> +  call dramfs_fs_init # initialize dramfs
> +  lw a0, 0(sp)        # argc
> +  lw a1, -4(sp)       # argv
> +  li a2, 0            # envp = NULL
> +  call main
> +  tail exit
> +
> +2:
> +  # Should never this point
> +  j 2b
> +```
> +
> +#### 4. Defining `_end` symbol in the linker command file:
> +
> +This can be done as shown in the sample linker script below:
> +
> +```
> +/* link.ld */
> +/* Sample linker command file */
> +
> +SECTIONS
> +{
> +  . = 0x80000000; /* text and data start at 0x80000000 */
> +
> +  .text : {
> +     *(.crtbegin)
> +     *(.text)
> +     *(.text.startup)
> +     *(.text.*)
> +  }
> +
> +  .data : {
> +    *(.data*)
> +    *(.rodata*)
> +    *(.sdata .sdata.* .srodata*)
> +  }
> +
> +  /* global pointer */
> +  _gp = .;
> +
> +  .bss : {
> +    *(.bss*)
> +    *(.sbss*)
> +  }
> +
> +  /* Initial heap pointer */
> +  _end = . ;
> +
> +  /* Initial stack pointer */
> +  _sp = 0x81000000;
> +}
> +```
> +
> +#### 5. Creating the DRAM lfs.c
> +
> +See instructions at https://github.com/bsg-external/bsg_dramfs_mklfs
> +
> +## Notes
> +
> +- Newlib is implemented on top of a set of operating system syscalls
> listed in [4]. Newlib/dramfs currently implements `sbrk`, `open`, `close`,
> `read`, `write`, `exit`, `lseek`, `stat` and `fstat`. These are sufficient
> to handle the vast majority of newlib POSIX calls. For those that are not
> supported, they return setting appropriate error number. We plan to
> increase this set over time, and also encourage your pull requests.
> +- Block size and count can be tweaked to improve performance depending on
> your system. More on this can be understood from [2].
> +- Current implementations of syscalls are *not* thread-safe. So, this can
> only be used for single threaded programs as of now.
> +
> +## References
> +
> +[1] Bootstrapping Idea:
> https://drive.google.com/open?id=1_Ie94nZvyvMjEb1GQTPzfcBNaVs6xfVXZ_bHTH5_z3k
>
> +[2] LittleFS: https://github.com/ARMmbed/littlefs
> +[3] RISC-V BSP:
> https://github.com/riscv/riscv-newlib/tree/riscv-newlib-3.1.0/libgloss/riscv
>
> +[4] Newlib OS interface: https://sourceware.org/newlib/libc.html#Syscalls
>
> +[5] Newlib porting guide:
> https://www.embecosm.com/appnotes/ean9/ean9-howto-newlib-1.0.html
> diff --git a/libgloss/dramfs/configure.in b/libgloss/dramfs/configure.in
> new file mode 100644
> index 000000000..5694013d4
> --- /dev/null
> +++ b/libgloss/dramfs/configure.in
> @@ -0,0 +1,45 @@
> +#=========================================================================
> +# configure.ac for riscv libgloss and crt0
> +#=========================================================================
> +
> +#-------------------------------------------------------------------------
> +# Setup
> +#-------------------------------------------------------------------------
> +
> +AC_INIT([crt0.S])
> +AC_CONFIG_SRCDIR([crt0.S])
> +AC_CONFIG_AUX_DIR([${srcdir}/../..])
> +
> +#-------------------------------------------------------------------------
> +# Checks for programs
> +#-------------------------------------------------------------------------
> +
> +LIB_AC_PROG_CC
> +AC_CHECK_TOOL([AR],[ar])
> +AC_CHECK_TOOL([RANLIB],[ranlib])
> +AC_PROG_INSTALL
> +
> +#-------------------------------------------------------------------------
> +# Output
> +#-------------------------------------------------------------------------
> +
> +if test "$srcdir" = "." ; then
> +  if test "${with_target_subdir}" != "." ; then
> +    libgloss_topdir="${srcdir}/${with_multisrctop}../../.."
> +  else
> +    libgloss_topdir="${srcdir}/${with_multisrctop}../.."
> +  fi
> +else
> +  libgloss_topdir="${srcdir}/../.."
> +fi
> +AC_CONFIG_AUX_DIR($libgloss_topdir)
> +AC_CONFIG_FILES(Makefile,
> +. ${libgloss_topdir}/config-ml.in,
> +srcdir=${srcdir}
> +target=${target}
> +with_multisubdir=${with_multisubdir}
> +ac_configure_args="${ac_configure_args} --enable-multilib"
> +CONFIG_SHELL=${CONFIG_SHELL-/bin/sh}
> +libgloss_topdir=${libgloss_topdir}
> +)
> +AC_OUTPUT
> diff --git a/libgloss/dramfs/crt0.S b/libgloss/dramfs/crt0.S
> new file mode 100644
> index 000000000..218d23104
> --- /dev/null
> +++ b/libgloss/dramfs/crt0.S
> @@ -0,0 +1,44 @@
> +/* Copyright (c) 2017  SiFive Inc. All rights reserved.
> +
> +   This copyrighted material is made available to anyone wishing to use,
> +   modify, copy, or redistribute it subject to the terms and conditions
> +   of the FreeBSD License.   This program is distributed in the hope that
> +   it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
> +   including the implied warranties of MERCHANTABILITY or FITNESS FOR
> +   A PARTICULAR PURPOSE.  A copy of this license is available at
> +   http://www.opensource.org/licenses.
> +*/
> +
> +#=========================================================================
> +# crt0.S : Entry point for RISC-V user programs
> +#=========================================================================
> +
> +  .text
> +  .global _start
> +  .type   _start, @function
> +_start:
> +  # Initialize global pointer
> +.option push
> +.option norelax
> +1:auipc gp, %pcrel_hi(__global_pointer$)
> +  addi  gp, gp, %pcrel_lo(1b)
> +.option pop
> +
> +  # Clear the bss segment
> +  la      a0, _edata
> +  la      a2, _end
> +  sub     a2, a2, a0
> +  li      a1, 0
> +  call    memset
> +
> +  la      a0, __libc_fini_array   # Register global termination functions
> +  call    atexit                  #  to be called upon exit
> +  call    __libc_init_array       # Run global initialization functions
> +
> +  call    dramfs_fs_init             # initialize dramfs
> +  lw      a0, 0(sp)                  # a0 = argc
> +  addi    a1, sp, __SIZEOF_POINTER__ # a1 = argv
> +  li      a2, 0                      # a2 = envp = NULL
> +  call    main
> +  tail    exit
> +  .size  _start, .-_start
> diff --git a/libgloss/dramfs/sys_close.c b/libgloss/dramfs/sys_close.c
> new file mode 100644
> index 000000000..fcb0a4faa
> --- /dev/null
> +++ b/libgloss/dramfs/sys_close.c
> @@ -0,0 +1,41 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +#include "dramfs_fdtable.h"
> +#include "dramfs_fs.h"
> +
> +/* Close a file.  */
> +int
> +_close(int fd)
> +{
> +  if(dramfs_check_fd(fd) < 0) {
> +    return -1;
> +  }
> +
> +  return dramfs_free_fd(fd);
> +}
> diff --git a/libgloss/dramfs/sys_execve.c b/libgloss/dramfs/sys_execve.c
> new file mode 100644
> index 000000000..8448ed6ae
> --- /dev/null
> +++ b/libgloss/dramfs/sys_execve.c
> @@ -0,0 +1,40 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +
> +#undef errno
> +extern int errno;
> +
> +/* Transfer control to a new process. Minimal implementation for a
> +   system without processes from newlib documentation.  */
> +int
> +_execve(const char *name, char *const argv[], char *const env[])
> +{
> +  errno = ENOMEM;
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_exit.c b/libgloss/dramfs/sys_exit.c
> new file mode 100644
> index 000000000..d402bbe09
> --- /dev/null
> +++ b/libgloss/dramfs/sys_exit.c
> @@ -0,0 +1,41 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <unistd.h>
> +#include "dramfs_fs.h"
> +
> +/* Exit a program without cleaning up files.  */
> +void
> +_exit(int exit_status) {
> +  // close stdio
> +  close(0);
> +  close(1);
> +  close(2);
> +
> +  dramfs_exit(exit_status);
> +  while(1);
> +}
> diff --git a/libgloss/dramfs/sys_fork.c b/libgloss/dramfs/sys_fork.c
> new file mode 100644
> index 000000000..6994ad55c
> --- /dev/null
> +++ b/libgloss/dramfs/sys_fork.c
> @@ -0,0 +1,39 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +
> +#undef errno
> +extern int errno;
> +
> +/* Create a new process. Minimal implementation for a system without
> +   processes from newlib documentation.  */
> +int _fork()
> +{
> +  errno = EAGAIN;
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_fstat.c b/libgloss/dramfs/sys_fstat.c
> new file mode 100644
> index 000000000..2ba8952da
> --- /dev/null
> +++ b/libgloss/dramfs/sys_fstat.c
> @@ -0,0 +1,48 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <sys/stat.h>
> +#include <dramfs_fs.h>
> +#include <dramfs_fdtable.h>
> +
> +int
> +_fstat(int file, struct stat *st)
> +{
> +  lfs_file_t *fptr;
> +  struct lfs_info finfo;
> +
> +  if(dramfs_check_fd(file) < 0)
> +    return -1;
> +  else
> +    fptr = dramfs_get_file(file);
> +
> +  st->st_mode = S_IFREG;
> +  st->st_size = (off_t) fptr->size;
> +  st->st_blksize = (blksize_t) dramfs_fs_cfg.block_size;
> +  st->st_blocks  = (blkcnt_t) dramfs_fs_cfg.block_count;
> +  return 0;
> +}
> diff --git a/libgloss/dramfs/sys_getpid.c b/libgloss/dramfs/sys_getpid.c
> new file mode 100644
> index 000000000..15ea50a09
> --- /dev/null
> +++ b/libgloss/dramfs/sys_getpid.c
> @@ -0,0 +1,36 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +/* Get process id. This is sometimes used to generate strings unlikely
> +   to conflict with other processes. Minimal implementation for a
> +   system without processes just returns 1.  */
> +
> +int
> +_getpid()
> +{
> +  return 1;
> +}
> diff --git a/libgloss/dramfs/sys_gettimeofday.c
> b/libgloss/dramfs/sys_gettimeofday.c
> new file mode 100644
> index 000000000..ac66268bf
> --- /dev/null
> +++ b/libgloss/dramfs/sys_gettimeofday.c
> @@ -0,0 +1,40 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <sys/time.h>
> +#include <errno.h>
> +
> +#undef errno
> +extern int errno;
> +
> +/* Get the current time.  Only relatively correct.  */
> +int
> +_gettimeofday(struct timeval *tp, void *tzp)
> +{
> +  errno = EINVAL;
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_isatty.c b/libgloss/dramfs/sys_isatty.c
> new file mode 100644
> index 000000000..f372dfda2
> --- /dev/null
> +++ b/libgloss/dramfs/sys_isatty.c
> @@ -0,0 +1,36 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +/* Query whether output stream is a terminal. For consistency with the
> +   other minimal implementations, which only support output to stdout,
> +   this minimal implementation is suggested by the newlib docs.  */
> +
> +int
> +_isatty(int file)
> +{
> +  return 1;
> +}
> diff --git a/libgloss/dramfs/sys_kill.c b/libgloss/dramfs/sys_kill.c
> new file mode 100644
> index 000000000..3a2597d25
> --- /dev/null
> +++ b/libgloss/dramfs/sys_kill.c
> @@ -0,0 +1,40 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +
> +#undef errno
> +extern int errno;
> +
> +/* Send a signal. Minimal implementation for a system without processes
> +   just causes an error.  */
> +int
> +_kill(int pid, int sig)
> +{
> +  errno = EINVAL;
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_link.c b/libgloss/dramfs/sys_link.c
> new file mode 100644
> index 000000000..fd2af719d
> --- /dev/null
> +++ b/libgloss/dramfs/sys_link.c
> @@ -0,0 +1,38 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +
> +#undef errno
> +extern int errno;
> +
> +/* Establish a new name for an existing file. Minimal implementation */
> +int _link(const char *old_name, const char *new_name)
> +{
> +  errno = EMLINK;
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_lseek.c b/libgloss/dramfs/sys_lseek.c
> new file mode 100644
> index 000000000..27c25c305
> --- /dev/null
> +++ b/libgloss/dramfs/sys_lseek.c
> @@ -0,0 +1,44 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <sys/types.h>
> +#include <dramfs_fs.h>
> +#include <dramfs_fdtable.h>
> +
> +/* Set position in a file.  */
> +off_t
> +_lseek(int file, off_t ptr, int dir)
> +{
> +  lfs_file_t *fptr;
> +
> +  if(dramfs_check_fd(file) < 0)
> +    return -1;
> +  else
> +    fptr = dramfs_get_file(file);
> +
> +  return lfs_file_seek(&dramfs_fs, fptr, ptr, dir);
> +}
> diff --git a/libgloss/dramfs/sys_open.c b/libgloss/dramfs/sys_open.c
> new file mode 100644
> index 000000000..5580d5c4d
> --- /dev/null
> +++ b/libgloss/dramfs/sys_open.c
> @@ -0,0 +1,64 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +#include <fcntl.h>
> +#include "dramfs_fdtable.h"
> +#include "dramfs_fs.h"
> +
> +/* Open a file.  */
> +int
> +_open(const char *name, int flags, int mode)
> +{
> +  int fd = dramfs_reserve_fd();
> +  int lfs_flags = 0;
> +
> +  // File open flags mapping
> +  lfs_flags |= (flags & O_RDONLY  ) ? LFS_O_RDONLY   : 0;
> +  lfs_flags |= (flags & O_WRONLY  ) ? LFS_O_WRONLY   : 0;
> +  lfs_flags |= (flags & O_RDWR    ) ? LFS_O_RDWR     : 0;
> +  lfs_flags |= (flags & O_APPEND  ) ? LFS_O_APPEND   : 0;
> +  lfs_flags |= (flags & O_CREAT   ) ? LFS_O_CREAT    : 0;
> +  lfs_flags |= (flags & O_TRUNC   ) ? LFS_O_TRUNC    : 0;
> +  lfs_flags |= (flags & O_EXCL    ) ? LFS_O_EXCL     : 0;
> +  lfs_flags |= (flags & O_NONBLOCK) ? LFS_O_NONBLOCK : 0;
> +
> +  if(fd < 0) {
> +    return -1;
> +  } else {
> +    lfs_file_t *fptr = dramfs_get_file(fd);
> +
> +    int ret = lfs_file_open(&dramfs_fs, fptr, name, lfs_flags);
> +
> +    if(ret < 0) {
> +      errno = ret;
> +      return -1;
> +    } else {
> +      return fd;
> +    }
> +  }
> +}
> diff --git a/libgloss/dramfs/sys_read.c b/libgloss/dramfs/sys_read.c
> new file mode 100644
> index 000000000..8ef6b6a45
> --- /dev/null
> +++ b/libgloss/dramfs/sys_read.c
> @@ -0,0 +1,67 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +#include <sys/types.h>
> +#include "dramfs_fdtable.h"
> +#include "dramfs_fs.h"
> +
> +/* Read from a file.  */
> +ssize_t _read(int fd, void *ptr, size_t len)
> +{
> +  if(dramfs_check_fd(fd) < 0) {
> +    return -1;
> +  }
> +
> +  if(fd == 0) {
> +    uint8_t *data = (uint8_t *)ptr;
> +
> +    // Return early on len == 0
> +    if (len == 0) return (ssize_t) 0;
> +
> +    int ch;
> +    if (dramfs_nonblock_fd(fd) == 0) {
> +      // Block to read just 1 character to start
> +      while ((ch = dramfs_getchar()) == -1);
> +    } else {
> +      // Read the first character, and return immediately if it's EOF
> +      if ((ch = dramfs_getchar()) == -1) return (ssize_t) 0;
> +    }
> +
> +    // Keep reading until new
> +    int i = 0;
> +    do {
> +      data[i++] = ch;
> +      if (i == len) break;
> +    } while ((ch = dramfs_getchar()) != -1);
> +
> +    return (ssize_t) i;
> +  }
> +
> +  lfs_file_t *fptr = dramfs_get_file(fd);
> +  return (ssize_t) lfs_file_read(&dramfs_fs, fptr, ptr, (lfs_size_t) len);
> +}
> diff --git a/libgloss/dramfs/sys_sbrk.c b/libgloss/dramfs/sys_sbrk.c
> new file mode 100644
> index 000000000..300356a08
> --- /dev/null
> +++ b/libgloss/dramfs/sys_sbrk.c
> @@ -0,0 +1,49 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +// Dynamic allocation in the dram
> +// TODO: add mutex
> +extern char _end[]; /* _end is set in the linker command file */
> +
> +char *heap_ptr = _end;
> +
> +/*
> + * sbrk -- changes heap size size. Get nbytes more
> + *         RAM. We just increment a pointer in what's
> + *         left of memory on the board.
> + */
> +char *
> +_sbrk (nbytes)
> +     int nbytes;
> +{
> +  char        *base;
> +
> +  base = heap_ptr;
> +  heap_ptr += nbytes;
> +
> +  return base;
> +}
> diff --git a/libgloss/dramfs/sys_stat.c b/libgloss/dramfs/sys_stat.c
> new file mode 100644
> index 000000000..f19309e16
> --- /dev/null
> +++ b/libgloss/dramfs/sys_stat.c
> @@ -0,0 +1,50 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +#include <sys/stat.h>
> +#include <dramfs_fs.h>
> +
> +/* Status of a file (by name).  */
> +
> +int
> +_stat(const char *file, struct stat *st)
> +{
> +  struct lfs_info finfo;
> +
> +  int res = lfs_stat(&dramfs_fs, file, &finfo);
> +  if(res < 0) {
> +    errno = res;
> +    return -1;
> +  } else {
> +    st->st_mode = S_IFREG;
> +    st->st_size = (off_t) finfo.size;
> +    st->st_blksize = (blksize_t) dramfs_fs_cfg.block_size;
> +    st->st_blocks  = (blkcnt_t) dramfs_fs_cfg.block_count;
> +    return 0;
> +  }
> +}
> diff --git a/libgloss/dramfs/sys_times.c b/libgloss/dramfs/sys_times.c
> new file mode 100644
> index 000000000..1c8ed9ceb
> --- /dev/null
> +++ b/libgloss/dramfs/sys_times.c
> @@ -0,0 +1,35 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <sys/times.h>
> +
> +/* Timing info for current process. Minimal implementation */
> +clock_t
> +_times(struct tms *buf)
> +{
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_unlink.c b/libgloss/dramfs/sys_unlink.c
> new file mode 100644
> index 000000000..4f4c4c750
> --- /dev/null
> +++ b/libgloss/dramfs/sys_unlink.c
> @@ -0,0 +1,39 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +
> +#undef errno
> +extern int errno;
> +
> +/* Remove a file's directory entry.  */
> +int
> +_unlink(const char *name)
> +{
> +  errno = ENOENT;
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_wait.c b/libgloss/dramfs/sys_wait.c
> new file mode 100644
> index 000000000..b593511fe
> --- /dev/null
> +++ b/libgloss/dramfs/sys_wait.c
> @@ -0,0 +1,39 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +
> +#undef errno
> +extern int errno;
> +
> +/* Wait for a child process. Minimal implementation for a system without
> +   processes just causes an error.  */
> +int _wait(int *status)
> +{
> +  errno = ECHILD;
> +  return -1;
> +}
> diff --git a/libgloss/dramfs/sys_write.c b/libgloss/dramfs/sys_write.c
> new file mode 100644
> index 000000000..082ef748d
> --- /dev/null
> +++ b/libgloss/dramfs/sys_write.c
> @@ -0,0 +1,52 @@
> +/*
> + * Copyright (c) 2023, University of Washington
> + * All rights reserved.
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are
> met:
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> the
> + *       documentation and/or other materials provided with the
> distribution.
> + *     * Neither the name of the University of Washington nor the
> + *       names of its contributors may be used to endorse or promote
> products
> + *       derived from this software without specific prior written
> permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> "AS IS" AND
> + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> IMPLIED
> + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
> + * DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF WASHINGTON BE LIABLE FOR
> ANY
> + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
> DAMAGES
> + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
> SERVICES;
> + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
> CAUSED AND
> + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> OF THIS
> + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <errno.h>
> +#include <sys/types.h>
> +#include "dramfs_fdtable.h"
> +#include "dramfs_fs.h"
> +
> +/* Write to a file.  */
> +ssize_t
> +_write(int fd, const void *ptr, size_t len)
> +{
> +  if(dramfs_check_fd(fd) < 0) {
> +    return -1;
> +  }
> +
> +  // write to console if it's stdout
> +  if(fd == 1 || fd==2) {
> +    for(int i=0; i<len; i++){
> +      char* cp = (char*) ptr;
> +      dramfs_sendchar(cp[i]);
> +    }
> +    return len;
> +  }
> +
> +  lfs_file_t *fptr = dramfs_get_file(fd);
> +  return (ssize_t) lfs_file_write(&dramfs_fs, fptr, ptr, (lfs_size_t)
> len);
> +}
> --
> 2.16.5
>
>