From: Jes Sorensen <jes@wildopensource.com>
To: Krzysztof Halasa <khc@pm.waw.pl>
Cc: "David S. Miller" <davem@redhat.com>,
linux-kernel@vger.kernel.org, zaitcev@redhat.com,
alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH] RFC: kills consistent_dma_mask
Date: 19 Aug 2003 05:21:08 -0400 [thread overview]
Message-ID: <m3u18erojf.fsf@trained-monkey.org> (raw)
In-Reply-To: <m365kvufjx.fsf@defiant.pm.waw.pl>
>>>>> "Krzysztof" == Krzysztof Halasa <khc@pm.waw.pl> writes:
Krzysztof> "David S. Miller" <davem@redhat.com> writes:
>> The ia64 support code to do things with consistent_dma_mask just
>> isn't in the tree yet.
Krzysztof> Ok. Any pointer so I can see how is it used?
drivers/net/tg3.c was the case where we needed it first. If you grab
the official ia64 kernel patch and look in the arch/ia64/sn/io code
you will find places that consider it.
>> Because the other platforms don't to do anything special wrt. this
>> they can just ignore consitent_dma_mask altogether.
Krzysztof> No. The documentation states that consistent_dma_mask (and
Krzysztof> not dma_mask) will be used when doing
Krzysztof> pci_alloc_consistent(). This is, obviously, false on most
Krzysztof> platforms.
It's not being used on those platforms because I couldn't implement it
on all of them - I just don't have the hardware. We implemented it on
ia64 because thats where we needed it, Andi Kleen then implemented it
on x86_64 because he needed it there. If there are PPC boxes out there
with similar issues then I am sure that the PPC maintainers will
implement support for this when they need it.
Krzysztof> It is perfectly reasonable to expect that
Krzysztof> setting consistent_dma_mask to, say, 28 bits will cause
Krzysztof> pci_alloc_consistent to return memory from first 256
Krzysztof> MB. This is not true on most platforms, for example i386
Krzysztof> happily allocs memory near the top in such case.
The default for pci_alloc_consistent() on ia32 is that
pci_dev->consistent_dma_mask == 32 bit. If you need something else for
a reason, please feel free to implement support for it.
Krzysztof> If we really need two masks, they can't be ignored on some
Krzysztof> archs.
So *fix* it! This is Linux, it's Free Software, you have the source,
you have the right to fix bugs!
Jes
next prev parent reply other threads:[~2003-08-19 9:21 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-17 22:34 [PATCH] RFC: kills consistent_dma_mask Krzysztof Halasa
2003-08-18 6:37 ` David S. Miller
2003-08-18 12:44 ` Krzysztof Halasa
2003-08-18 12:43 ` David S. Miller
2003-08-18 15:54 ` Krzysztof Halasa
2003-08-18 16:49 ` David S. Miller
2003-08-18 18:21 ` Krzysztof Halasa
2003-08-18 18:50 ` David S. Miller
2003-08-18 21:58 ` Krzysztof Halasa
2003-08-19 9:24 ` Jes Sorensen
2003-08-19 9:21 ` Jes Sorensen [this message]
2003-08-18 13:00 ` Jes Sorensen
2003-08-18 8:07 ` Christoph Hellwig
2003-08-18 15:15 ` Pete Zaitcev
2003-08-18 16:14 ` Krzysztof Halasa
2003-08-19 9:16 ` Jes Sorensen
2003-08-19 9:49 ` Krzysztof Halasa
2003-08-19 10:15 ` Jes Sorensen
2003-08-19 9:03 ` Jes Sorensen
2003-08-19 13:07 ` Alan Cox
2003-08-19 13:20 ` Jes Sorensen
2003-08-19 16:55 ` David S. Miller
2003-08-19 18:33 ` Alan Cox
2003-08-19 18:31 ` David S. Miller
2003-08-19 20:31 ` Krzysztof Halasa
2003-08-22 11:54 ` Krzysztof Halasa
2003-08-23 17:11 ` Jes Sorensen
2003-08-24 12:06 ` Krzysztof Halasa
2003-08-24 13:00 ` David S. Miller
2003-08-24 19:58 ` Krzysztof Halasa
2003-08-25 8:50 ` Jes Sorensen
2003-08-30 21:18 ` Krzysztof Halasa
2003-08-31 1:50 ` David S. Miller
2003-08-31 12:52 ` Alan Cox
2003-08-31 15:24 ` Krzysztof Halasa
2003-09-01 5:22 ` David S. Miller
2003-09-01 7:34 ` Krzysztof Halasa
2003-09-01 7:43 ` David S. Miller
2003-09-01 17:14 ` Krzysztof Halasa
2003-09-01 17:28 ` David S. Miller
2003-09-01 18:24 ` Krzysztof Halasa
2003-09-01 7:54 ` Alan Cox
2003-09-01 7:52 ` David S. Miller
2003-09-01 16:27 ` Krzysztof Halasa
2003-09-01 17:33 ` David S. Miller
2003-08-25 8:47 ` Jes Sorensen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=m3u18erojf.fsf@trained-monkey.org \
--to=jes@wildopensource.com \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=davem@redhat.com \
--cc=khc@pm.waw.pl \
--cc=linux-kernel@vger.kernel.org \
--cc=zaitcev@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).