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Date: Thu, 25 Feb 2010 12:19:04 +0100
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH] scsi: Make device scsi-disk reject /dev/sg*
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To: Markus Armbruster <armbru@redhat.com>
Cc: qemu-devel@nongnu.org

On 02/25/10 11:23, Markus Armbruster wrote:
> You're supposed to use scsi-generic for that.  Which rejects anything
> but /dev/sg*.

Well, it isn't *that* easy.  The SG_IO ioctl used by scsi-generic works 
on tons of devices in linux, not only /dev/sg*.  I've seen patches 
floading around which change the check bdrv_is_sg() into "try SG_IO and 
see if it works", which would allow to use /dev/sda with both scsi-disk 
and scsi-generic depending on what you want.  Which makes alot of sense.

Making that change needs some extra care though to avoid existing 
configurations switching from scsi-disk to scsi-generic unnoticed.

cheers,
   Gerd