[ECOS] Re: Different section placement for kernel and application

[Grant Edwards <grant.b.edwards@gmail.com>]

On 2011-01-28, Martin R??sch <martin.roesch@neratec.com> wrote:
> Hi,
>
> Thanks for your answers.
>
>> In theory, you could apply section attributes to all of the kernel
>> functions (or all of the application functions) so that you could
>> separate them at link time into different output sections.
>
> That's what I was thinking of. I think this can be achieved with a
> modified version of the cortexm.ld linker script, which is used to
> generate the target.ld linker script.

I'm curious why you want to do this.  What benefit does it provide?

> I studied the documentation of the GNU Linker Scripts and found some
> hints to place the sections based from the input object file. I made
> a try in the RAM Layout .ldi file:
>
> // eCos memory layout
>
> #include <pkgconf/hal.h>
> #include <cyg/infra/cyg_type.inc>
>
> MEMORY
> {
>     sram  : ORIGIN = 0x20000000, LENGTH = 0x00010000
>     flash : ORIGIN = 0x08000000, LENGTH = 0x00080000
>     rom   : ORIGIN = 0x60000000, LENGTH = 0x00800000
>     ram1  : ORIGIN = 0x64000000, LENGTH = 0x00800000-CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE
>     ram2  : ORIGIN = 0x68000000, LENGTH = 0x00800000
> }
>
> SECTIONS
> {
>     SECTIONS_BEGIN
>     SECTION_rom_vectors (flash, 0x08010000, LMA_EQ_VMA)
>     SECTION_RELOCS (flash, ALIGN (0x8), LMA_EQ_VMA)
>     .ecos.text ALIGN (0x8) : LMA_EQ_VMA
>     {
>     vectors.o(.text*) vectors.o(.gnu.warning) vectors.o(.gnu.linkonce.t.*) vectors.o(.init) vectors.o(.glue_7) vectors.o(.glue_7t)
>     extras.o(.text*) extras.o(.gnu.warning) extras.o(.gnu.linkonce.t.*) extras.o(.init) extras.o(.glue_7) extras.o(.glue_7t)
>     libtarget.a(.text*) libtarget.a(.gnu.warning) libtarget.a(.gnu.linkonce.t.*) libtarget.a(.init) libtarget.a(.glue_7) libtarget.a(.glue_7t)
>     } > flash
>     .ecos.rodata ALIGN (0x8) : LMA_EQ_VMA
>     {
>     FORCE_OUTPUT;
>     vectors.o(.rodata*) vectors.o(.gnu.linkonce.r.*)
>     extras.o(.rodata*) extras.o(.gnu.linkonce.r.*)
>     libtarget.a(.rodata*) libtarget.a(.gnu.linkonce.r.*)  
>     } > flash
>     SECTION_sram (sram, 0x20000400, LMA_EQ_VMA)
>     SECTION_text (ram1, 0x64008000, LMA_EQ_VMA)
>     SECTION_fini (ram1, ALIGN (0x8), LMA_EQ_VMA)
>     SECTION_rodata (ram1, ALIGN(0x8), LMA_EQ_VMA)
>     SECTION_rodata1 (ram1, ALIGN (0x8), LMA_EQ_VMA)
>     SECTION_fixup (ram1, ALIGN (0x8), LMA_EQ_VMA)
>     SECTION_gcc_except_table (ram1, ALIGN (0x8), LMA_EQ_VMA)
>     SECTION_eh_frame (ram1, ALIGN (0x8), LMA_EQ_VMA)
>     SECTION_got (ram1, ALIGN (0x8), LMA_EQ_VMA)
>     CYG_LABEL_DEFN(__heap1) = ALIGN (0x8);
>     SECTION_data (ram2, 0x68000000, LMA_EQ_VMA)
>     SECTION_bss (ram2, ALIGN (0x8), LMA_EQ_VMA)
>     SECTIONS_END
> }
>
> hal_vsr_table = 0x20000000;
> hal_virtual_vector_table = hal_vsr_table + 128*4;
> hal_startup_stack = 0x64800000;
>
> With this modification the sections of the eCos components (from vectors.o, extras.o and libtarget.a)
> are placed in the flash region when loaded with the RedBoot ROM monitor and GDB,
> but a Bus error occurs in the reset_vector function:
>
> Loading section .rom_vectors, size 0x8 lma 0x8010000
> Loading section .ecos.text, size 0x10bcc lma 0x8010008
> Loading section .ecos.rodata, size 0x49dc lma 0x8020bd8
> Loading section .ARM.exidx, size 0x10 lma 0x64008000
> Loading section .text, size 0x924 lma 0x64008010
> Loading section .rodata, size 0x108 lma 0x64008938
> Loading section .data, size 0xdcc lma 0x68000000
> Start address 0x8010009, load size 93624
> Transfer rate: 9 KB/sec, 300 bytes/write.
>
> Program received signal SIGBUS, Bus error.
> reset_vector () at [snip]/repo/ecos/packages/hal/cortexm/arch/current/src/vectors.S:100
> 100                ldr     sp,=hal_startup_stack
>
> Is there a chance to get this working?

I think so, yes.

AFAIK, GDB stubs don't know how to program flash (and there's no
indication it attempted to do so), so you're using some other
mechanism to load the flash portion of the code?

-- 
Grant Edwards               grant.b.edwards        Yow! Did I SELL OUT yet??
                                  at               
                              gmail.com            


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