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
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