Re: uses of cmpxchg/xadd in spinlock.h and rwsem.h vs. CONFIG_M386

From: H. Peter Anvin
Date: Tue May 12 2009 - 11:51:43 EST


Jan Beulich wrote:
> While looking at a completely different issue I happened to grep for uses of
> xadd, and it would appear to me that there got uses added that would make
> a M386-configured SMP kernel die on an actual i386.
>
> Oh, for the rwsem case I see - it would use the RWSEM_GENERIC_SPINLOCK case
> when selecting M386. But I see nothing similar for the ticket spinlocks - am
> I overlooking something?

It's quite possible we break 386 on a regular basis... I'm not sure how
many people even in the embedded industry run current kernels on
386-compatible hardware. Most embedded hardware is at least 486.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

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