From: Chris Wedgwood <cw@f00f.org>
To: Jes Sorensen <jes@sunsite.dk>
Cc: "David S. Miller" <davem@redhat.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Jeff Garzik <jgarzik@mandrakesoft.com>,
Ben LaHaise <bcrl@redhat.com>,
"\"MEHTA,HIREN (A-SanJose,ex1)\"" <hiren_mehta@agilent.com>,
"'linux-kernel@vger.kernel.org'" <linux-kernel@vger.kernel.org>
Subject: Re: (reposting) how to get DMA'able memory within 4GB on 64-bit m
Date: Thu, 12 Jul 2001 09:54:21 +1200 [thread overview]
Message-ID: <20010712095421.A2298@weta.f00f.org> (raw)
In-Reply-To: <3B46FDF1.A38E5BB6@mandrakesoft.com> <E15Ir5R-0005lR-00@the-village.bc.nu> <15175.2003.773317.101601@pizda.ninka.net> <d3y9pv8ee5.fsf@lxplus015.cern.ch>
In-Reply-To: <d3y9pv8ee5.fsf@lxplus015.cern.ch>
On Wed, Jul 11, 2001 at 09:16:50PM +0200, Jes Sorensen wrote:
The overhead is going be negligeble, the overhead of highmem itself is
much worse. Not to mention that today some dma_addr_t's might not be
packed properly in data structure hence they ending up taking 8 bytes
anyway.
What kind of packing makes a 32-bit value take 8-bytes on any
currently supported archicture? The worst-case I can think of is
7-bytes in the case of misaligned by 3 (e.g. __attribute__((packed))
struct blah { char foo[3]; long bar }; sort of thing).
--cw
next prev parent reply other threads:[~2001-07-11 21:54 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-06-28 16:20 (reposting) how to get DMA'able memory within 4GB on 64-bit m achi ne MEHTA,HIREN (A-SanJose,ex1)
2001-06-28 19:41 ` Jes Sorensen
2001-06-28 21:45 ` David S. Miller
2001-06-28 22:01 ` David S. Miller
2001-06-28 22:20 ` Jes Sorensen
2001-06-28 22:28 ` Alan Cox
2001-07-02 8:09 ` Jens Axboe
2001-06-28 22:24 ` Ben LaHaise
2001-07-02 8:09 ` Jens Axboe
2001-06-28 22:27 ` David S. Miller
2001-06-28 22:29 ` David S. Miller
2001-06-28 22:31 ` Ben LaHaise
2001-06-28 22:40 ` (reposting) how to get DMA'able memory within 4GB on 64-bit m Alan Cox
2001-06-28 22:38 ` (reposting) how to get DMA'able memory within 4GB on 64-bit m achi ne David S. Miller
2001-06-28 22:45 ` Ben LaHaise
2001-06-28 22:48 ` David S. Miller
2001-06-28 22:48 ` (reposting) how to get DMA'able memory within 4GB on 64-bit m Alan Cox
2001-06-28 22:55 ` (reposting) how to get DMA'able memory within 4GB on 64-bit m achi ne Jes Sorensen
2001-06-29 9:16 ` David S. Miller
2001-06-29 9:56 ` Alan Cox
2001-06-29 20:37 ` David S. Miller
2001-07-05 21:06 ` Jes Sorensen
2001-07-05 23:47 ` David S. Miller
2001-07-05 23:50 ` Ben LaHaise
2001-07-06 13:31 ` Jes Sorensen
2001-07-06 23:46 ` David S. Miller
2001-07-07 3:58 ` Ben LaHaise
2001-07-07 5:35 ` David S. Miller
2001-07-07 12:06 ` (reposting) how to get DMA'able memory within 4GB on 64-bit m Alan Cox
2001-07-07 12:17 ` Jeff Garzik
2001-07-07 12:21 ` Alan Cox
2001-07-07 13:00 ` David S. Miller
2001-07-11 19:16 ` Jes Sorensen
2001-07-11 21:54 ` Chris Wedgwood [this message]
2001-07-11 23:17 ` David S. Miller
2001-07-11 23:07 ` David S. Miller
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