Messages in this thread | | | Subject | Re: Linux 3.3-rc4 | From | Ian Kent <> | Date | Tue, 21 Feb 2012 13:39:47 +0800 |
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On Mon, 2012-02-20 at 21:06 -0800, Linus Torvalds wrote: > On Mon, Feb 20, 2012 at 8:52 PM, Ian Kent <raven@themaw.net> wrote: > > > > I think the patch attached to your original post needs a little work if > > that is to be used. Correct me if I'm wrong but AFAICT there are more > > architectures that use 8-byte alignment than just x86-64, such as alpha, > > ia64 and ppc64 and I believe they may also be used in a compat mode. > > The only issue is compat mode, and afaik, all other architectures > except for x86-32 do __u64 with natural alignment. > > So all 64-bit architectures use natural alignment, the only issue is > the alignment of __u64 in 32-bit mode. > > So it really is *not* about 8-byte alignment. Quite the reverse. It's > about 4-byte alignment of 64-bit entities, and I suspect x86-32 is the > only one that does that. > > See "compat_u64", and notice how only in arch/x86/include/asm/compat.h > do we have > > typedef u64 __attribute__((aligned(4))) compat_u64; > > So it really is limited to only x86.
Thanks, I wasn't aware of this.
> > Linus
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