r13 is non-volatile?
segher at kernel.crashing.org
Fri Sep 9 03:01:18 EST 2005
> Was looking at merging some code between ppc32 & ppc64 and noticed
> that in ppc32 we consider r13 to be part of the non-volatile register
> set. Is this really correct?
I believe so, yes.
> r13 is suppose to be sdata pointer in ppc32
sdata pointer is non-volatile by definition...
> and system thread id in ppc64.
The 64-bit kernel uses GPR13 as the PACA pointer, so it handles
it specially -- it treats the userland values of the register
as non-volatile, though.
> So I'm wondering should we really be considering it NV on ppc32?
Yeah. I'm sure there is some way to make the macro's identical
between 32- and 64-bit, though.
More information about the Linuxppc-dev