Re: understanding elf_machine_load_address

[Andreas Jaeger <aj@suse.de>]

Daniel Jacobowitz <dan@debian.org> writes:

> On Sat, Dec 08, 2001 at 04:18:53PM +0100, Andreas Jaeger wrote:
>> >        "   bltzal $0, here\n"
>> >        "   nop\n"
>> >        "here:      subu %0, $31, %0\n"
>> 
>> Subtract shared address of "here" from address of "here" at build time
>> - and you know at which address byte 0 of the shared library is
>>   loaded.
>
> Wait a second.  Does bltzal fill in $31 even on a not-taken branch? 
> Because bltzal $0 should never be taken.  My handy MIPS reference and
> SPIM seem to agree that it won't fill in $31.

That's what I've asked myself also when fixing the dynamic linker.
But Ralf convinced me that $31 will get filled in (and I verified that
it did) - otherwise the dynamic linker would not work on any system at
all.

But it might be worth checking if Guido notices a problem.

Btw. could anybody send me a patch documenting this instruction so
that next time everybody knows directly what's going on?

Thanks,
Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj