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Re: [PATCH] Handle mtsprg and mfsprg properly for BookE
On Sun, Mar 13, 2005 at 03:34:33PM -0800, Alex Rosenberg wrote:
> On Mar 9, 2005, at 7:58 PM, Alan Modra wrote:
> >There remains the question of which spr number should be used by
> >privileged programs for read access to sprg4 through sprg7. Does the
> >non-privileged spr number work when privileged? I would think it
> >probably does, but I'm just guessing..
>
> I think the documentation is the problem here.
>
> Originally, the user mode read-only SPRG were supposed to be referred
> to as USPRG.
Makes sense. Consistent with the spr numbering for USPRG0 too.
I propose that gas adopt this syntax. ie.
mtsprg and mtsprg[0-7] writes spr272..279 (as we currently do)
mfsprg and mfsprg[0-7] read the same regs as mtsprg
mfusprg0 reads spr256 (as we currently do)
Add new mfusprg[3-7] insns which read spr259..263
Add a new mfusprg insn which reads spr256..263
--
Alan Modra
IBM OzLabs - Linux Technology Centre