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relax jalr $t9 [R_MIPS_JALR symbol] to bal symbol

Alexandre Oliva aoliva@redhat.com
Tue Mar 25 10:58:00 GMT 2003 
On Mar 25, 2003, Richard Henderson <rth@redhat.com> wrote:

> One *could* have a PT_LOAD segment with >= 256MB alignment.
> Technically this should work.  This is somewhat tricky to 
> implement, since mmap doesn't take an alignment argument,
> so it would be difficult to honor in ld.so.  (Indeed, I
> notice that glibc doesn't.)

glibc does pass a suggested map address to the kernel, computed using
the PH alignment.

> But, we've not been discussing using jal in ET_DYN objects.
> Instead, using them only in ET_EXEC objects.  In that case
> the load address is fixed, and thus we can check at link
> time that we won't be crossing a segment boundary.

Right.  We even have relocation we can use for this: R_MIPS_26.
However, at least for now, I'll have to leave the implementation of
this alternate relaxation as an exercise for the reader :-)

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                 aoliva@{redhat.com, gcc.gnu.org}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist                Professional serial bug killer
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