[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1329802787.2226.33.camel@perseus.themaw.net>
Date: Tue, 21 Feb 2012 13:39:47 +0800
From: Ian Kent <raven@...maw.net>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: David Miller <davem@...emloft.net>, thomas@...3r.de,
linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: Linux 3.3-rc4
On Mon, 2012-02-20 at 21:06 -0800, Linus Torvalds wrote:
> On Mon, Feb 20, 2012 at 8:52 PM, Ian Kent <raven@...maw.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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists