From: Kevin Wolf <kwolf@redhat.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Jes.Sorensen@redhat.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: [PATCH] Disable O_DIRECT for physical CDROM/DVD drives
Date: Tue, 20 Jul 2010 18:09:45 +0200 [thread overview]
Message-ID: <4C45CA49.6080901@redhat.com> (raw)
In-Reply-To: <4C45C355.2000204@codemonkey.ws>
Am 20.07.2010 17:40, schrieb Anthony Liguori:
> On 07/20/2010 10:17 AM, Jes.Sorensen@redhat.com wrote:
>> From: Jes Sorensen<Jes.Sorensen@redhat.com>
>>
>> O_DIRECT (cache=none) requires sector alignment, however the physical
>> sector size of CDROM/DVD drives is 2048, as opposed to most disk
>> devices which use 512. QEMU is hard coding 512 all over the place, so
>> allowing O_DIRECT for CDROM/DVD devices does not work.
>>
>> Signed-off-by: Jes Sorensen<Jes.Sorensen@redhat.com>
>>
>
> Wouldn't a better solution be to have a cdrom_read/cdrom_write hook that
> did the appropriate bouncing?
We already have code that does some bouncing, we'd just need to teach it
to use different sizes than 512. Duplicating everything wouldn't be a
nice solution.
> Silently disabling something a user explicitly asked for is not a good
> option. In the very least, it should error out entirely.
Yeah, that's probably better.
Kevin
next prev parent reply other threads:[~2010-07-20 16:09 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-20 15:17 [Qemu-devel] [PATCH] Disable O_DIRECT for physical CDROM/DVD drives Jes.Sorensen
2010-07-20 15:40 ` Kevin Wolf
2010-07-20 16:04 ` Jes Sorensen
2010-07-20 16:12 ` Kevin Wolf
2010-07-20 16:18 ` Jes Sorensen
2010-07-20 15:40 ` [Qemu-devel] " Anthony Liguori
2010-07-20 16:02 ` Jes Sorensen
2010-07-20 16:03 ` Anthony Liguori
2010-07-20 16:06 ` Jes Sorensen
2010-07-20 16:16 ` David S. Ahern
2010-07-20 16:20 ` Jes Sorensen
2010-07-20 16:09 ` Kevin Wolf [this message]
2010-07-20 16:12 ` Jes Sorensen
2010-07-20 16:45 ` [Qemu-devel] " Natalia Portillo
2010-07-20 16:48 ` Jes Sorensen
2010-07-20 17:57 ` Anthony Liguori
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=4C45CA49.6080901@redhat.com \
--to=kwolf@redhat.com \
--cc=Jes.Sorensen@redhat.com \
--cc=anthony@codemonkey.ws \
--cc=qemu-devel@nongnu.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.