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Date: Mon, 01 Mar 2010 09:13:53 +0100
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] Re: [PATCH] scsi: Make device scsi-disk reject
	/dev/sg*
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	<201002280145.38065.paul@codesourcery.com>
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To: Paul Brook <paul@codesourcery.com>
Cc: qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>

On 02/28/10 02:45, Paul Brook wrote:
>> 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.
>
> Don't we really want to be testing !bdrv_is_block() ?

That would work for linux.  Dunno about the BSD.

cheers,
   Gerd