On 09/10/2012 06:04 PM, Kevin D. Kissell wrote:
On 09/10/2012 05:29 PM, Maciej W. Rozycki wrote:
I do wonder however why we have these instructions to save/restore $25
in SAVE_SOME/RESTORE_SOME. This dates back to 2.4 at the very least.
Ralf, any insights?
Hi, guys. Maybe the fact that it's used for dispatching PIC calls has
something to do with it?
I don't think so. It is call clobbered in all Linux ABIs. So there is
never a need to save it. It even has the pseudonym of $t9 indicating
that it will get clobbered.
The other call clobbered registers that happen to be saved are for the
nefarious uses of the kernel itself (a0..a6 for system call restarting),
I think this is just left over cruft.
David Daney
/K.
