From: Palmer Dabbelt <palmer@dabbelt.com>
To: joseph@codesourcery.com
Cc: libc-alpha@sourceware.org, Andrew Waterman <andrew@sifive.com>,
Darius Rad <darius@bluespec.com>,
dj@redhat.com
Subject: Re: RISC-V glibc port v2
Date: Wed, 20 Dec 2017 20:25:00 -0000 [thread overview]
Message-ID: <mhng-02b41a27-5e72-45f2-8c2b-17968eca5185@palmer-si-x1c4> (raw)
In-Reply-To: <alpine.DEB.2.20.1712201552150.30469@digraph.polyomino.org.uk>
On Wed, 20 Dec 2017 08:04:50 PST (-0800), joseph@codesourcery.com wrote:
> On Tue, 19 Dec 2017, Palmer Dabbelt wrote:
>
>> We're planning on supporting 6 glibc configurations on RISC-V, all of which we
>> internally run regression tests on:
>>
>> * -march=rv64imafdc -mabi=lp64d -- what we expect to be the most used
>> configuration
>> * -march=rv64imac -mabi=lp64 -- soft floating point
>> * -march=rv64imafdc -mabi=lp64 -- soft float ABI, but allowed to use
>> hardware floating point instruction. This
>> is like softfp in ARM land.
>> * -march=rv32imafdc -mabi=ilp32d -- rv32i is a 32-bit ISA
>> * -march=rv32imac -mabi=ilp32
>> * -march=rv32imafdc -mabi=ilp32
>
> But you also define dynamic linker names for the "f" ABI variants (lp64f,
> ilp32f), so, as per my previous comments, those should be built by
> build-many-glibcs.py and included in at least some testing.
Oh, sorry -- lp64f and ilp32f aren't going to be supported in glibc/Linux, just
to reduce the number of ABI combinations. I'll remove them from the v3.
>> * Our test suite results are very bad, but I believe this is because we're
>> running on QEMU's user-mode emulation which is known to be both buggy and
>> incomplete. I'm bringing up userspace again to produce a more reasonable
>> test suite run, which will hopefully have a much cleaner run.
>
> Full execution test results - meaning on QEMU system-mode emulation or
> hardware, not user-mode emulation - are definitely needed to judge whether
> a port is ready for inclusion (I've suggested < 20 architecture-specific
> FAILs as indicative of a state comparable to other reasonably
> well-maintained ports).
OK -- the only reason I've been running user-mode emulation is because that's
how our test scripts are setup. I'm working getting enough of a userspace
together to run the test suite natively now. We've had this before, there's
just nothing based on the 4.15 RC headers and I want to make sure everything
absolutely lines up.
> Note that there is no need for the glibc you are testing to be
> ABI-compatible with any glibc in your userspace's root filesystem, so you
> don't need to rebuild userspace (if e.g. it's using older glibc with
> different symbol versions) to test current glibc. It *does* need to be
> able to find libgcc_s and libstdc++ shared libraries at runtime, but you
> can copy those into the glibc build directory before running tests.
>
>> * I've only added one configuration to build-many-glibcs.py, which I haven't
>> actually run yet. I'll rectify this, but I wanted to at least get something
>> out so everyone was on the same page here -- the commit is more of a TODO
>> than an actual commit.
>
> There should be at least one per ABI in there. Additional variants for an
> ABI (e.g. varying whether hard or soft float is used with a soft-float
> ABI) are optional, depending on whether you think they provide useful
> additional coverage of significantly different code in glibc getting
> built. Such variants should typically only need listing in extra_glibcs
> so they get built in a "glibcs" build but not a "compilers" build.
>
> Depending on the multilib configurations used by GCC you may or may not
> need as many GCC builds as different ABIs (e.g. MIPS has 24 ABIs, so 24
> glibc builds in build-many-glibcs.py, but only 8 separate GCC builds, each
> with multilibs for 3 ABIs).
We currently support all the glibc targets in a single GCC build and we hope to
keep it that way, so hopefully this says a bit easier for us. Thanks, though
-- part of the reason I only put one entry in was because I wasn't sure what to
do :).
> It's important to make sure that the build is completely clean for the GCC
> / glibc variants you add, including no failures of compilation tests.
> (That is, clean given that you substitute a checkout of Linus's git tree
> for the default release version of Linux - obviously the builds can't be
> clean from the bots until the Linux 4.15 release comes out.)
Makes sense. I'll be sure this is the case.
>> * I'm not sure what the right the to do with VDSO_NAME_LINUX_4_15 is. It seems
>> odd that there's nothing newer than 2.6.29 in there.
>
> That probably indicates that any more recent vDSOs added to the Linux
> kernel used a version number that reflected when people started developing
> them, rather than the version when they actually got into the kernel.
> Once it gets into the kernel, the symbol version used for the vDSO by the
> kernel becomes part of the kernel/userspace ABI, so fixed even if in some
> sense it's the "wrong" version.
>
> If the RISC-V Linux kernel port uses a LINUX_4.15 symbol version for its
> vDSO, adding VDSO_NAME_LINUX_4_15 seems right to me.
OK, that makes sense. During the Linux submission process it was suggested we
use 4.15.0, I guess I'm just a bit surprised we're the only ones wo have
something newer than 2.6.29.
>> * Many copyright cleanups.
>
> Of course, if work on the port goes past 31 December before it's ready to
> go in, you'll need to update all copyrights to use <year>-2018 ranges.
Sounds good. DJ wrote a copyright checking script, so it should be easy to
find everything.
Thanks for all the feedback. I'll go through your messages, and though I
haven't read them yet I assume we'll be submitting a v3.
next prev parent reply other threads:[~2017-12-20 20:25 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-20 7:23 Palmer Dabbelt
2017-12-20 7:23 ` [PATCH v2 03/15] RISC-V: Startup and Dynamic Loading Code Palmer Dabbelt
2017-12-20 16:38 ` Joseph Myers
2017-12-23 3:25 ` Palmer Dabbelt
2017-12-23 3:33 ` DJ Delorie
2017-12-23 12:52 ` Joseph Myers
2017-12-20 7:23 ` [PATCH v2 02/15] RISC-V: ABI Implementation Palmer Dabbelt
2017-12-20 16:31 ` Joseph Myers
2017-12-23 3:25 ` Palmer Dabbelt
2017-12-23 3:30 ` DJ Delorie
2017-12-20 7:23 ` [PATCH v2 04/15] RISC-V: Thread-Local Storage Support Palmer Dabbelt
2017-12-20 16:45 ` Joseph Myers
2017-12-23 19:10 ` Palmer Dabbelt
2017-12-20 7:23 ` [PATCH v2 05/15] RISC-V: Generic <string.h> Routines Palmer Dabbelt
2017-12-20 16:48 ` Joseph Myers
2017-12-23 22:01 ` Palmer Dabbelt
2018-01-01 0:52 ` Joseph Myers
2018-01-03 15:46 ` Adhemerval Zanella
2018-01-03 16:03 ` Joseph Myers
2018-01-03 16:08 ` Adhemerval Zanella
2017-12-20 7:23 ` [PATCH v2 01/15] RISC-V: Build Infastructure Palmer Dabbelt
2017-12-20 14:05 ` Dmitry V. Levin
2017-12-20 20:25 ` Palmer Dabbelt
2017-12-20 16:22 ` Joseph Myers
2017-12-20 16:49 ` Adhemerval Zanella
2017-12-23 2:22 ` Palmer Dabbelt
2017-12-23 12:44 ` Joseph Myers
2017-12-25 20:58 ` Palmer Dabbelt
2018-01-01 1:21 ` Joseph Myers
2017-12-20 16:43 ` Joseph Myers
2017-12-23 3:41 ` Palmer Dabbelt
2017-12-23 12:53 ` Joseph Myers
2017-12-20 7:24 ` [PATCH v2 08/15] RISC-V: RV32D, RV64F, and RV64D Support Palmer Dabbelt
2017-12-20 7:24 ` [PATCH v2 07/15] RISC-V: RV32F Support Palmer Dabbelt
2017-12-20 17:01 ` Joseph Myers
2017-12-20 17:04 ` Joseph Myers
2017-12-24 1:26 ` Palmer Dabbelt
2017-12-24 0:37 ` Palmer Dabbelt
2018-01-01 0:57 ` Joseph Myers
2017-12-20 7:24 ` [PATCH v2 09/15] RISC-V: Atomic and Locking Routines Palmer Dabbelt
2017-12-20 17:08 ` Joseph Myers
2017-12-24 1:26 ` Palmer Dabbelt
2017-12-20 7:24 ` [PATCH v2 12/15] RISC-V: Linux Startup and Dynamic Loading Code Palmer Dabbelt
2017-12-20 7:24 ` [PATCH v2 10/15] RISC-V: Linux Syscall Interface Palmer Dabbelt
2017-12-20 16:57 ` Adhemerval Zanella
2017-12-24 0:24 ` Palmer Dabbelt
2018-01-01 0:56 ` Joseph Myers
2018-01-03 13:43 ` Christoph Hellwig
2018-01-03 15:56 ` Adhemerval Zanella
2018-01-09 1:30 ` Palmer Dabbelt
2018-01-09 11:16 ` Adhemerval Zanella
2017-12-20 17:24 ` Joseph Myers
2017-12-25 19:47 ` Palmer Dabbelt
2017-12-20 7:24 ` [PATCH v2 11/15] RISC-V: Linux ABI Palmer Dabbelt
2017-12-20 17:33 ` Joseph Myers
2017-12-25 19:47 ` Palmer Dabbelt
2018-01-01 1:04 ` Joseph Myers
2018-01-02 20:59 ` Joseph Myers
2017-12-20 7:24 ` [PATCH v2 06/15] RISC-V: Generic <math.h> and soft-fp Routines Palmer Dabbelt
2017-12-20 16:50 ` Joseph Myers
2017-12-24 0:24 ` Palmer Dabbelt
2017-12-20 7:24 ` [PATCH v2 15/15] Add RISC-V to build-many-glibcs.py Palmer Dabbelt
2017-12-20 7:24 ` [PATCH v2 14/15] Add linux-4.15 VDSO hash for RISC-V Palmer Dabbelt
2017-12-20 7:24 ` [PATCH v2 13/15] Add RISC-V dynamic relocations to elf.h Palmer Dabbelt
2017-12-20 16:04 ` RISC-V glibc port v2 Joseph Myers
2017-12-20 20:25 ` Palmer Dabbelt [this message]
2017-12-20 20:42 ` Joseph Myers
2017-12-20 17:40 ` Joseph Myers
2017-12-25 20:20 ` Palmer Dabbelt
2018-01-01 1:20 ` Joseph Myers
2018-01-03 13:37 ` Christoph Hellwig
2018-01-03 13:42 ` Joseph Myers
2017-12-20 21:11 ` Joseph Myers
2017-12-20 21:45 ` Palmer Dabbelt
2017-12-25 12:57 ` Adhemerval Zanella
2018-01-01 0:58 ` Joseph Myers
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