From: Stefan Hajnoczi <stefanha@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Kevin Wolf <kwolf@redhat.com>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
"Justin M. Forbes" <jforbes@redhat.com>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: [PATCH] usb-msd: Add usb-storage, removable=on|off property
Date: Mon, 17 Jan 2011 10:04:05 +0000 [thread overview]
Message-ID: <20110117100405.GA7123@stefanha-thinkpad.localdomain> (raw)
In-Reply-To: <20110117092126.GB19683@lst.de>
On Mon, Jan 17, 2011 at 10:21:26AM +0100, Christoph Hellwig wrote:
> The actual removable bit looks fine, but I don't think the connection of
> the change callback looks sane. What's the rationale for it?
Since we're using bdrv_set_removable(), the user may try to eject the
block device from the QEMU monitor. At that point we have a closed
BlockDriverState and all operations will (at best) error since there is
no medium.
The callback removes the USB MSD so that eject is equivalent to removing
the device. It's a hack and we could remove it, but then we're left
with a weird guest-visible state that you can't get into with a physical
USB thumbdrive.
I was considering not using bdrv_set_removable() and instead adding a
hint to the BlockDriverState which gets checked when constructing the
SCSI INQUIRY response. If we take that approach, then QEMU doesn't
consider the block device removable in the eject/change medium sense.
Stefan
next prev parent reply other threads:[~2011-01-17 10:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-15 0:00 [Qemu-devel] [PATCH] usb-msd: Add usb-storage, removable=on|off property Stefan Hajnoczi
2011-01-17 9:21 ` [Qemu-devel] " Christoph Hellwig
2011-01-17 10:04 ` Stefan Hajnoczi [this message]
2011-01-17 16:01 ` Christoph Hellwig
2011-01-17 18:08 ` Stefan Hajnoczi
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