On Thu, 06 Jul 2006 04:32:26 +0200, Magnus Damm wrote:
...
> > Not sure which approach is better but got a question. By definition, are
> > executable files supposed to be relocatable?
No. Unless you provide --emit-relocs.
> > Or we are just trying to do some hack by treating an R_386_32 type
> > relocation as R_386_RELATIVE effectively.
I did not dead with R_386_RELATIVE, only with R_386_32 and R_386_PC32.
The kernel build with mkdump patches would fail on R_386_RELATIVE:
http://mkdump.cvs.sourceforge.net/mkdump/linux/scripts/reltab.c?view=markup&pathrev=linux-2_6-minik
else RELOC_ASSERT("howto->name unknown"==NULL);
...
> Isn't the difference between R_386_32 and R_386_RELATIVE that the
> latter is a PC-relative addressing mode?
Such difference is between R_386_32 and R_386_PC32. R_386_RELATIVE is intended
for shared libraries only.
http://x86.ddj.com/ftp/manuals/tools/elf.pdf
> The addressing mode and the
> relocation type is setup by the compiler I think, and it is only up to
> me to follow it to make sure the address is calculated correctly...
Just the relocation type was incorrect in the 2.6.9 days so Eric W. Biederman
fixed it while I rather ignored it (and guessed it by the symbol address
instead).
> > Thinking aloud, How about compiling the kernel as shared library and then
> > performing the relocations in user space at load time instead of runtime.
This was irrelevant for mkdump as finally it created "bzImage" in its non-ELF
binary form as it always have been (with relocations handld internally during
its internal bootstrapping).
As kdump was messing with ELF and new kernel file format it is on you whether
you will use "-shared" or "--emit-relocs". "-shared" looks too dangerous to me
as it starts messing with GOTs, PLTs etc.
http://people.redhat.com/drepper/dsohowto.pdf
Still it may be possible to reach the same goals even with "-shared", maybe the
relocation types will be different (R_386_32->R_386_RELATIVE ?), their handling
will be still the same, though.
Regards,
Lace
_______________________________________________
fastboot mailing list
[email protected]
https://lists.osdl.org/mailman/listinfo/fastboot
