Re: [GIT PULL] x86/atomic changes for v2.6.35

From: H. Peter Anvin
Date: Wed May 19 2010 - 10:24:40 EST

On 05/19/2010 04:46 AM, Geert Uytterhoeven wrote:
> On Tue, May 18, 2010 at 00:45, Ingo Molnar <mingo@xxxxxxx> wrote:
>> Please pull the latest x86-atomic-for-linus git tree from:
>> git:// x86-atomic-for-linus
>> out-of-topic modifications in x86-atomic-for-linus:
>> ---------------------------------------------------
>> lib/Makefile # 86a8938: lib: Add self-test for atomic64_t
>> lib/atomic64.c # 9757789: lib: Fix atomic64_add_unless retu
>> lib/atomic64_test.c # a5c9161: x86, atomic64: In selftest, disti
>> # 25a304f: lib: Fix atomic64_inc_not_zero te
>> # 9efbcd5: lib: Fix atomic64_add_unless test
>> # d7f6de1: x86: Implement atomic[64]_dec_if_
>> # 8f4f202: lib: Only test atomic64_dec_if_po
>> # 86a8938: lib: Add self-test for atomic64_t
> Is having atomic64_t mandatory now?
> According to the allmodconfig build logs
> (,
> several architectures (at least m68k and mips) don't have it.
> Furthermore, the test fails to compile on a few architectures that do have it
> (parisc, s390, sh, ...).
> <boilerplate>
> It's a pity this wasn't raised/resolved between its detection in linux-next and
> before it entered mainline...
> </boilerplate>

Is having atomic64_t mandatory? Not yet, I don't think, but it probably
will be soon -- which is why there is a generic implementation
available. All those architectures just need to select
CONFIG_GENERIC_ATOMIC64 and voilÃ, problem solved.

As far as your boilerplate is concerned, I think Linus made it clear at
the Kernel Summit that is it not the obligation of x86/ARM/PowerPC to
slow down to not break the smaller architectures; it's the
responsibility of those architecture maintainers to keep up. Sorry.


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

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