From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:33172) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QAh6h-0003TZ-5B for qemu-devel@nongnu.org; Fri, 15 Apr 2011 07:22:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QAh6g-0001E3-5O for qemu-devel@nongnu.org; Fri, 15 Apr 2011 07:22:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19363) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QAh6f-0001Dz-OC for qemu-devel@nongnu.org; Fri, 15 Apr 2011 07:22:34 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p3FBMWGM017396 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 15 Apr 2011 07:22:33 -0400 Date: Fri, 15 Apr 2011 16:52:30 +0530 From: Amit Shah Message-ID: <20110415112230.GA6786@amit-x200.redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [RFC PATCH] block: Fix eject -f for locked devices List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: qemu-devel@nongnu.org On (Fri) 18 Feb 2011 [16:16:07], Markus Armbruster wrote: > From 8cd4978c9be6ff2bcc414bb1c1b258b96b9a74c1 Mon Sep 17 00:00:00 2001 > From: Markus Armbruster > Date: Fri, 18 Feb 2011 15:54:02 +0100 > > After forcefully ejecting media locked by the guest, you can't ever > again insert new media. > > Example: > > (qemu) info block > hda: type=hd removable=0 file=test.img ro=0 drv=raw encrypted=0 > cd: type=cdrom removable=1 locked=1 file=x.iso ro=0 drv=raw encrypted=0 > (qemu) eject cd > Device 'cd' is locked > (qemu) eject -f cd > (qemu) info block > hda: type=hd removable=0 file=test.img ro=0 drv=raw encrypted=0 > cd: type=cdrom removable=1 locked=1 [not inserted] > (qemu) change cd x.iso > Device 'cd' is locked > > Signed-off-by: Markus Armbruster > --- > I'm not entirely sure this is the appropriate fix, and that's why > there's RFC in the subject. > > Both IDE and SCSI devices expose their drive's BlockDriverState member > locked to the guest via mode sense. > > What does real hardware do when I force-eject media (typically by > rummaging in that little hole with a paperclip)? Does it actively > notify the OS? Does mode sense change? I think this should happen. Calling the 'change_cb' with a new CHANGE_EJECT parameter can notify the guest of the medium going from READY to NO_MEDIUM. The guest can then probe for the status of the tray. However, I currently don't know if devices are supposed to send such events to OSes, and how, if they are supposed to. We currently approximate this using ide_set_irq() for the cdrom case in cdrom_change_cb(). This patch looks sensible, though. > A possible alternative fix is to make do_change_block() ignore > bdrv_is_locked() when inserting media into an empty drive. > > block.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/block.c b/block.c > index b476479..295cf7b 100644 > --- a/block.c > +++ b/block.c > @@ -682,6 +682,7 @@ void bdrv_close(BlockDriverState *bs) > } > > /* call the change callback */ > + bs->locked = 0; > bs->media_changed = 1; > if (bs->change_cb) > bs->change_cb(bs->change_opaque, CHANGE_MEDIA); Amit