From: Jes Sorensen <jes@sunsite.dk>
To: "David S. Miller" <davem@redhat.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
jgarzik@mandrakesoft.com (Jeff Garzik),
bcrl@redhat.com (Ben LaHaise),
hiren_mehta@agilent.com ("MEHTA,HIREN (A-SanJose,ex1)"),
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: 11 Jul 2001 21:16:50 +0200 [thread overview]
Message-ID: <d3y9pv8ee5.fsf@lxplus015.cern.ch> (raw)
In-Reply-To: <3B46FDF1.A38E5BB6@mandrakesoft.com> <E15Ir5R-0005lR-00@the-village.bc.nu> <15175.2003.773317.101601@pizda.ninka.net>
In-Reply-To: "David S. Miller"'s message of "Sat, 7 Jul 2001 06:00:03 -0700 (PDT)"
>>>>> "David" == David S Miller <davem@redhat.com> writes:
David> Alan Cox writes:
>> I see no good way to optimise for 64bit dma on a 32bit box.
David> I'm actually not only talking about DAC device on 32-bit cpus.
David> Just as much, I'm talking about drivers for SAC-only devices
David> even on 64-bit cpus.
David> I took a lot of crap from driver authors when we started
David> pushing the PCI dma stuff on people, because of the dma_addr_t
David> people now had to keep around to unmap the thing later.
David> To a certain extent I agreed with these folks. I'll be gutting
David> myself if I make everyone eat twice as much space just to add
David> DAC support to the kernel :-)
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.
Jes
next prev parent reply other threads:[~2001-07-11 19:18 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 [this message]
2001-07-11 21:54 ` Chris Wedgwood
2001-07-11 23:17 ` David S. Miller
2001-07-11 23:07 ` David S. Miller
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