Maciej W. Rozycki wrote:
> On Mon, 15 Oct 2007, Franck Bui-Huu wrote:
>
>> Well, since .init.bss is declared as follow:
>>
>> .init.bss (NOLOAD) : {
>> ...
>> }
>>
>> data should not take any space in the image...
>
> The above only marks it as unloadable (cf. e.g. debugging information).
> It is still there.
>
So it seems there is no way from a linker script to specify that a
section has the nobits type, is it ?
After spending some fun time trying several different configurations
with gcc and ld, I noticed that gcc makes a section with @nobits
attribute if the section name starts with .bss.*
So calling .bss.init instead of .init.bss makes gcc do the right
thing. Here is a bit of tlbex.s:
.word 0
.section .bss.init,"aw",@nobits
.align 2
.type tlb_handler, @object
.size tlb_handler, 512
tlb_handler:
.space 512
.align 2
.type labels, @object
.size labels, 1024
labels:
.space 1024
Another test I did is to put .init.bss (not .bss.init) section right
before .bss section in order to have only one segment to load. And it
makes magically ld do the right thing. I must admit that I don't
understand why, and the lack of documentation doesn't help...
Unfortunately I don't know if we can rely on one of these
behaviours. IOW if they're going to work with all supported versions
of gcc/ld.
Anyway, I'll resubmit a new patchset for futher discussion.
Franck
