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Date: Tue, 6 Mar 2001 00:06:52 +0000
From: Kenn Humborg <kenn@linux.ie>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: kmalloc() alignment
Message-ID: <20010306000652.A13992@excalibur.research.wombat.ie>
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In-Reply-To: <3AA2C488.54A792AD@colorfullife.com>; from manfred@colorfullife.com on Sun, Mar 04, 2001 at 11:41:12PM +0100
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On Sun, Mar 04, 2001 at 11:41:12PM +0100, Manfred Spraul wrote:
> >
> > Does kmalloc() make any guarantees of the alignment of allocated 
> > blocks? Will the returned block always be 4-, 8- or 16-byte 
> > aligned, for example? 
> >
> 
> 4-byte alignment is guaranteed on 32-bit cpus, 8-byte alignment on
> 64-bit cpus.

So, to summarise (for 32-bit CPUs):

o  Alan Cox & Manfred Spraul say 4-byte alignment is guaranteed.

o  If you need larger alignment, you need to alloc a larger space,
   round as necessary, and keep the original pointer for kfree()

Maybe I'll just use get_free_pages, since it's a 64KB chunk that
I need (and it's only a once-off).

Thanks for your advice.

Later,
Kenn

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