Re: [PATCH] x86_64 : support atomic ops with 64 bits integer values

H. Peter Anvin
2008-08-16T15:08:38Z

Mathieu Desnoyers wrote:
> x86_64 add/sub atomic ops does not seems to accept integer values bigger
> than 32 bits as immediates. Intel's add/sub documentation specifies they
> have to be passed as registers.

This is correct; this is in fact true for all instructions except "mov".

Whether it's sign- or zero-extending is sometimes subtle, but not in
these cases.

Do you happen to know if this is a manifest bug in the current kernel
(i.e. if there is anywhere we're using more than ±2 GB as a constant to
these functions?)

Either way, I'll queue this up to tip:x86/urgent if Ingo hasn't already
since this is a pure bug fix.

-hpa