Hello Jeff,
----- Am 14. Jan 2020 um 17:37 schrieb Jeff Kubascik
jeff.kubas...@dornerworks.com:
> Hello,
>
> I have noticed a change in the linker section ".rtemsrwset" alignment which
> has
> affected the zImage header that was added with the arm/xen BSP. The zImage
> header uses the bsp_section_data_end symbol to determine the end of the
> image. I
> was able to track this change to the commit 234d155e linkersets: Revert to
> zero-length arrays.
>
> Here is the readelf output of the ticker.exe application just prior before
> commit
>
> Section Headers:
> [Nr] Name Type Addr Off Size ES Flg Lk Inf
> Al
> [15] .rtemsstack NOBITS 40100000 01358c 001000 00 WA 0 0
> 64
> [16] .data PROGBITS 40101000 101000 0004e0 00 WA 0 0
> 8
> [17] .rtemsrwset PROGBITS 401014e0 1014e0 000000 00 0 0
> 1
>
> Here is the output with the commit
>
> Section Headers:
> [Nr] Name Type Addr Off Size ES Flg Lk Inf
> Al
> [15] .rtemsstack NOBITS 40100000 01358c 001000 00 WA 0 0
> 64
> [16] .data PROGBITS 40101000 101000 0004e0 00 WA 0 0
> 8
> [17] .rtemsrwset PROGBITS 40101500 101500 000000 00 WA 0 0
> 64
>
> This shows that the alignment of the ".rtemsrwset" section changed from 1 byte
> to 64 bytes. This changes the start address of the section to be aligned, even
> though the section is empty.
>
> The bsp_section_data_end symbol is located at the end of the ".rtemsrwset"
> section. If the section is empty, the bsp_section_data_end symbol will contain
> the start address of the section.
>
> .data : ALIGN_WITH_INPUT {
> bsp_section_data_begin = .;
> *(.data .data.* .gnu.linkonce.d.*)
> SORT(CONSTRUCTORS)
> } > REGION_DATA AT > REGION_DATA_LOAD
> .data1 : ALIGN_WITH_INPUT {
> *(.data1)
> } > REGION_DATA AT > REGION_DATA_LOAD
> .rtemsrwset : ALIGN_WITH_INPUT {
> KEEP (*(SORT(.rtemsrwset.*)))
> bsp_section_data_end = .;
> } > REGION_DATA AT > REGION_DATA_LOAD
>
> When I convert the ticker.exe elf to a binary with objcopy, the binary doesn't
> include the ".rtemsrwset" section, since it's empty. As a result, the length
> of
> the binary doesn't match the bsp_section_data_end symbol. This is a problem
> for
> some zImage loaders that verify the image length.
>
> I'm not certain what would be the best way to fix the zImage header. Is there
> a
> different symbol that I should be using to get the end of the image? Maybe
> this
> is a bug with the linker script?
there is no bug in the linker script. In wkspace.c there is this linker set
declared:
RTEMS_LINKER_RWSET(
_Per_CPU_Data,
RTEMS_ALIGNED( CPU_CACHE_LINE_BYTES ) char
);
So, the .rtemsrwset contains an empty _Per_CPU_Data set which is properly
aligned.
In uniprocessor configuration, the cache alignment is superfluous. I will fix
this.
Why don't you use the file size of your binary created by objcopy to set the
image size?
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