From: Andreas Gruenbacher <agruen@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>,
Jan Engelhardt <jengelh@medozas.de>,
Eric Paris <eparis@redhat.com>,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
davem@davemloft.net
Subject: Re: Process to push changes to include/linux/types.h
Date: Fri, 15 Oct 2010 12:15:49 +0200 [thread overview]
Message-ID: <201010151215.49392.agruen@suse.de> (raw)
In-Reply-To: <20101015020134.e552d081.akpm@linux-foundation.org>
On Friday 15 October 2010 11:01:34 Andrew Morton wrote:
> On Fri, 15 Oct 2010 10:22:49 +0200 Andi Kleen <andi@firstfloor.org> wrote:
>
> > Jan Engelhardt <jengelh@medozas.de> writes:
> >
> > > I would be interested in knowing whether you - in whichever subsystems
> > > you happen to be active - would even need aligned_u64. Right now,
> > > the only users seem to be PPP and scsi_tgt besides Netfilter.
> >
> > Using aligned_u64 is good practice to avoid problems with the
> > 32bit/64bit compat layer. I would recommend it to anyone
> > adding a new user space interface passing a 64bit value.
> >
>
> What "problems" does it prevent when used for this?
64-bit values align to 4-byte boundaries on some 32-bit architectures like x86
and to 8-byte boundaries on 64-bit architetures. The new __aligned_64 type
enforces 8-byte alignment and so structs containing __aligned_64 values have
the same alignment on 32-bit and 64-bit architectures. No conversions are
necessary between 32-bit user-space and a 64-bit kernel.
Andreas
next prev parent reply other threads:[~2010-10-15 10:16 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-14 19:34 Process to push changes to include/linux/types.h Eric Paris
2010-10-14 19:45 ` Andi Kleen
2010-10-14 19:54 ` Andrew Morton
2010-10-14 21:26 ` Jan Engelhardt
2010-10-14 21:35 ` Eric Paris
2010-10-14 21:37 ` Andrew Morton
2010-10-14 21:46 ` Randy Dunlap
2010-10-14 21:50 ` Jan Engelhardt
2010-10-14 22:01 ` Andrew Morton
2010-10-14 22:13 ` Linus Torvalds
2010-10-14 23:05 ` Jan Engelhardt
2010-10-15 3:03 ` Abbrevieated SHA1s (Was: Re: Process to push changes to include/linux/types.h) Stephen Rothwell
2010-10-15 8:22 ` Process to push changes to include/linux/types.h Andi Kleen
2010-10-15 9:01 ` Andrew Morton
2010-10-15 10:15 ` Andreas Gruenbacher [this message]
2010-10-15 14:26 ` Andi Kleen
2010-10-15 14:44 ` Andreas Gruenbacher
2010-10-15 15:24 ` Jan Engelhardt
2010-10-15 10:13 ` Jan Engelhardt
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