Hi Albert,

On Tue, Feb 28, 2012 at 1:25 PM, Albert ARIBAUD albert.u.boot@aribaud.net wrote:

Hi Simon,

Le 21/02/2012 21:14, Simon Glass a écrit :

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Hi Albert,

On Tue, Feb 21, 2012 at 11:52 AM, Albert ARIBAUD albert.u.boot@aribaud.net  wrote:

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Hi Simon,

Le 21/02/2012 18:02, Simon Glass a écrit :

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• . = ALIGN(4);

This "ALIGN(4)" is what upsets my edminiv2 build and makes it not binary-identical. It is not in the current arm926ejs liner script. I will check if adding it to the current arm926ejs script produces a working and binary-identical u-boot.

OK, but realistically we copy a word at a time (at least) and the .rel.dyn region is going to be word-aligned I think. All we are doing here is making sure that the image ends on a word boundary, which seems reasonable to me.

In other words, I would like the __image_copy_start and __image_copy_end symbols to be word-aligned.

I understand the requirement and agree to it -- only, it seems to me it is already fulfilled in the current lds files, so I still fail to see what breaks 'near binary identity'.

If we add any symbols or change the value of any of them, then the binary file may change. You can see the differences by doing something like:

This statement is true in a very general fashion, but becomes false for many cases, including the one where the symbol is added at link stage and not referenced in the build, which is the case for edminiv2. Then the ELF file's symbol sections may change, but the .text and .data sections have no reason to.

I agree with that. But do you see this behaviour? I did initially, until I realized that it was just that '-dirty' was be appended to the version string, which was increasing the .rodata size and just changing all the offsets in the text section. Once I committed the change and rebuilt, the problem went away.

Please can you confirm what differences you are seeing with things like:

armv7a-cros-linux-gnueabi-objdump -h u-boot armv7a-cros-linux-gnueabi-objdump -t u-boot armv7a-cros-linux-gnueabi-objdump -d u-boot ...

Plus, you did not address my note that the current .lds already aligns the start and end of copy section to a multiple of 4.

I think I missed that comment. I saw that you said that the ALIGN before __image_copy_end was not in the arm926-ejs link script, but when I looked I did in fact see it, e.g. in e37ae40:

arch/arm/cpu/arm926ejs/u-boot.lds: ... . = .; __u_boot_cmd_start = .; .u_boot_cmd : { *(.u_boot_cmd) } __u_boot_cmd_end = .;

. = ALIGN(4); ^^^^^^^^^^^^^

.rel.dyn : { ...

In the link script in this patch I have:

. = ALIGN(4);

. = .; __u_boot_cmd_start = .; .u_boot_cmd : { *(.u_boot_cmd) } __u_boot_cmd_end = .;

. = ALIGN(4);

__image_copy_end = .;

.rel.dyn : { __rel_dyn_start = .;

Granted, the last ALIGN should not be needed since the size of commands should be word-aligned anyway, and the first command is clearly word-aligned, but it does make things clear I think. Can you please explain more what you mean by ' the current .lds already aligns the start and end of copy section to a multiple of 4'. And also, how you would like me to change this patch. Just remove the last ALIGN?

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armv7a-cros-linux-gnueabi-objdump -b binary -m arm -D u-boot.bin

on each file (but I guess you know that).

Yes, plus 'od -t x1z -A x u-boot.bin > u-boot.lst' :) and it does not explain why the .text and .data sections should undergo any change when the .lds introduces a symbol that neither section references.

See my note above about 'dirty', but if you are saying it is due to the ALIGN, I am not sure what to say. I don't see that, so perhaps it is best to email the commands you are using so I can replicate.

Regards, Smion

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Regards, Simon

Amicalement,

Albert.