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Re: Objcopy problem
On Tue, Oct 30, 2007 at 02:48:11PM +0000, Andrew STUBBS wrote:
> H.J. Lu wrote:
> >How do you load a section with file size 0?
>
> One does not. Here's the effect of this command in the old tools:
>
> $ sh4objcopy a.out a2.out --set-section-flags
> .post_text_reserve=contents,alloc,load,readonly,code
> $ sh4objdump -ph a2.out
>
> a2.out: file format elf32-shl
>
> Program Header:
> LOAD off 0x00000080 vaddr 0x00000000 paddr 0x00000000 align 2**7
> filesz 0x0000016c memsz 0x0000016c flags rwx
>
> Sections:
> Idx Name Size VMA LMA File off Algn
> 0 .text 0000000c 00000000 00000000 00000080 2**1
> CONTENTS, ALLOC, LOAD, READONLY, CODE
> 1 .post_text_reserve 00000160 0000000c 0000000c 0000008c 2**0
> CONTENTS, ALLOC, LOAD, READONLY, CODE
> 2 .comment 00000043 00000000 00000000 000001ec 2**0
> CONTENTS, READONLY
>
> As you can see, the section now _has_ a file size. This was the point of
> the exercise - the section contents may now be overwritten with the
> final data (in this case a digital signature used to verify the other
> sections).
>
> The linker will not allow us to create a loadable section for which we
> do not yet know the contents. Therefore, this trick is used to convert
> the elf file into the form we need.
Please open a bug report. I will take a look. Thanks.
H.J.