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Subjectwant to clarify powerpc assembly conventions in head.S and entry.S


I'm doing some work in head.S and entry.S, and I just wanted to make
sure that I had the conventions down.

According to the docs I read, r0 and r3-12 are caller-saves. They seem
to be saved in EXCEPTION_PROLOG_2 (head.S) and restored in
ret_from_except() (entry.S). Thus, if I add code in entry.S I should be
able to use any of those registers, without having to worry about
restoring them myself--correct?

Also, I'm a bit confused about the three instances of the following line
in entry.S:

stwcx. r0,0,r1 /* to clear the reservation */

I don't see the corresponding lwarx instruction. What reservation is it
referring to?

Thanks,

Chris
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