On Wed, 27 Oct 1999, Benjamin Herrenschmidt wrote:
> I beleive this could be improved by using linker tricks to have the
> linker store this size in a place where the code can fetch it via
> pc-relative access, but I don't know ld well enough to write such a script.
Excuse me for the delay, I just read the ld documentation last night.
(http://www.gnu.org/manual/ld-2.9.1/html_mono/ld.html)
Hey the elfbios.lds script is already there, almost good!
There are errors in it however:
>SECTIONS
>{
> _text = .; /* Text and read-only data */
> .text : {
> *(.text)
> *(.fixup)
> *(.gnu.warning)
> *(.rodata)
> }
> _etext = .; /* End of text section */
>
> _data = .;
> .data : { /* Data */
> *(.data)
> }
>
> _edata = .; /* End of data section */
>
> _bss_start = .; /* BSS */
> .bss : {
> *(.bss)
> }
> _end = . ;
>}
_text and _data (_etext and _edata as well for aesthetic reasons) should
be _inside_ .text et .data sections definitions because .text et .data value
are forced by Makefile variables TEXTADDR and DATAADDR.
So right now _text is 0,
.text is forced by Makefile to 0x41000C0 (providing I use bank 0),
_etext= 0x4100xxxx
Therefore _etext - _text = 4100xxxx instead of xxxx.
Same thing with _data = 0x4100xxxx ,
.data is force by Makefile to 0x1000
_edata 0x1xxx and
_edata - data = BEFFxxxx
A really Bad Thing!
We can even calculate the size value at link time by creating new symbols like
_sz_data = _edata - _data;
or even
_sz_data = SIZEOF(.data)
which are equivalent.
I therefore propose the corrected following elfbios.lds:
>SECTIONS
>{
> /* Text and read-only data */
> .text : {
> _text = .;
> *(.text)
> *(.fixup)
> *(.gnu.warning)
> *(.rodata)
> _etext = .; /* End of text section */
> }
> _sz_text = SIZEOF(.text) ;
>
> _data = .;
> .data : { /* Data */
> *(.data)
> }
>
> _edata = .; /* End of data section */
> _sz_data = SIZEOF(.data) ;
>
> /* BSS */
> .bss : {
> _bss_start = .;
> *(.bss)
> _end = . ;
> }
> _sz_bss = SIZEOF(.bss)
>}
What do we think?
--
Fran�ois Desloges
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