Re: want to clarify powerpc assembly conventions in head.Sand entry.S

[Benjamin Herrenschmidt]

> You knew this was coming...  What's special about syscalls?  There's the
> r3 thing, but other than that...

The whole codepath is a bit different, there's the syscall trace,
we can avoid saving much more registers are syscalls are function
calls and so can clobber the non volatiles, etc...

> Thanks for your help with this stuff.  As I've been slowly wrapping my
> head around it I've been continuously wishing for some kind of design
> rules document describing the various paths through the assembly code,
> along with register conventions and such.  I eventually did find the
> conventions linked off the penguinppc website, but it was not obvious
> from just reading the code or the ppc stuff in the Documentation directory.
>
> Chris
--
Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>


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