From: Chuck Ebbert <cebbert@redhat.com>
To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: hancockrwd@gmail.com, ak@linux.intel.com,
linux-kernel@vger.kernel.org, dwmw2@infradead.org
Subject: Re: b44 driver causes panic when using swiotlb
Date: Tue, 1 Feb 2011 16:18:59 -0500 [thread overview]
Message-ID: <20110201161859.467676b0@katamari> (raw)
In-Reply-To: <20110201102707C.fujita.tomonori@lab.ntt.co.jp>
On Tue, 1 Feb 2011 10:28:00 +0900
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote:
>
> swiotlb allocates the bounce buffer when a system boots up. We can't
> allocate much in GFP_DMA. swiotlb uses somewhere under 4GB. So it
> can't help devices that have odd dma_mask (that is, except for 4GB).
>
> Unfortunately, Such device needs to do own custom bouncing or needs
> their subsystem to does that.
I think we're chasing the wrong problem here.
swiotlb uses alloc_bootmem_low_pages() to try to get buffers as low
in memory as possible. I asked someone who is hitting this bug to
try 2.6.36 and he reports the buffers really are low there:
2.6.36: 5c00000
2.6.37: db600000
So something happened very early in the 2.6.37-rc cycle that changed
this behavior. I tried looking at the bootmem code but could not see
the problem. The only related option I could find in .config was this:
# CONFIG_NO_BOOTMEM is not set
It was set this way in both .36 and .37.
next prev parent reply other threads:[~2011-02-01 21:22 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-31 15:54 b44 driver causes panic when using swiotlb Chuck Ebbert
2011-01-31 16:36 ` Andi Kleen
2011-02-01 0:54 ` Robert Hancock
2011-02-01 1:28 ` FUJITA Tomonori
2011-02-01 3:22 ` Robert Hancock
2011-02-01 5:22 ` FUJITA Tomonori
2011-02-15 0:47 ` Robert Hancock
2011-02-01 21:18 ` Chuck Ebbert [this message]
2011-02-02 0:06 ` FUJITA Tomonori
2011-02-02 0:09 ` FUJITA Tomonori
2011-02-01 18:07 ` Andi Kleen
2011-02-01 21:44 ` Robert Hancock
2011-02-01 13:54 ` FUJITA Tomonori
2011-02-14 11:59 ` FUJITA Tomonori
2011-02-14 16:41 ` Arkadiusz Miśkiewicz
2011-02-15 0:39 ` FUJITA Tomonori
2011-02-15 22:03 ` Chuck Ebbert
[not found] <4D478EDC.4070004@lwfinger.net>
2011-02-01 4:53 ` Larry Finger
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=20110201161859.467676b0@katamari \
--to=cebbert@redhat.com \
--cc=ak@linux.intel.com \
--cc=dwmw2@infradead.org \
--cc=fujita.tomonori@lab.ntt.co.jp \
--cc=hancockrwd@gmail.com \
--cc=linux-kernel@vger.kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.