From: James Bottomley <James.Bottomley@steeleye.com>
To: Jes Sorensen <jes@wildopensource.com>
Cc: Jamie Wellnitz <Jamie.Wellnitz@emulex.com>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: virt_to_page/pci_map_page vs. pci_map_single
Date: 03 Nov 2003 12:48:42 -0600 [thread overview]
Message-ID: <1067885332.2076.13.camel@mulgrave> (raw)
Jamie> The Document/DMA-mapping.txt in 2.6.0-test9 says "To map a
Jamie> single region, you do:" and then shows pci_map_single. Is
Jamie> DMA-mapping.txt in need of patching?
Sounds like it needs an update.
Erm, I don't think so. pci_map_single() covers a different use case
from pci_map_page().
The thing pci_map_single() can do that pci_map_page() can't is cope with
contiguous regions greater than PAGE_SIZE in length (which you get
either from kmalloc() or __get_free_pages()). This feature is used in
the SCSI layer for instance.
There has been talk of deprecating dma_map_single() in favour of
dma_map_sg() (i.e. make all transfers use scatter/gather and eliminate
dma_map_single() in favour of a single sg entry table) but nothing has
been done about it (at least as far as I know).
James
next reply other threads:[~2003-11-03 18:49 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-03 18:48 James Bottomley [this message]
2003-11-03 22:03 ` virt_to_page/pci_map_page vs. pci_map_single Jamie Wellnitz
2003-11-04 9:48 ` Jes Sorensen
2003-11-04 16:35 ` Matt Porter
2003-11-04 16:47 ` James Bottomley
2003-11-04 17:11 ` Matt Porter
2003-11-04 16:43 ` James Bottomley
2003-11-05 16:23 ` Anton Blanchard
2003-11-06 8:28 ` Jes Sorensen
[not found] <NuZH.1a5.7@gated-at.bofh.it>
[not found] ` <NI6s.1MM.3@gated-at.bofh.it>
[not found] ` <NMtC.7Vs.21@gated-at.bofh.it>
[not found] ` <NNSy.1Cd.1@gated-at.bofh.it>
[not found] ` <NV3O.5w7.19@gated-at.bofh.it>
[not found] ` <NWCA.7Qv.19@gated-at.bofh.it>
2003-11-04 8:41 ` Ihar 'Philips' Filipau
-- strict thread matches above, loose matches on Subject: below --
2003-11-02 18:12 Jamie Wellnitz
2003-11-03 8:10 ` Jes Sorensen
2003-11-03 12:52 ` Jamie Wellnitz
2003-11-03 14:17 ` Jes Sorensen
2003-11-03 22:02 ` David Mosberger
2003-11-04 0:41 ` David S. Miller
2003-11-04 9:44 ` Jes Sorensen
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