From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 1/2 v1] blkdrv: Add queue limits parameters for sg block
	drive
Date: Wed, 22 Aug 2012 16:13:44 +0200
Message-ID: <5034E918.4030305@redhat.com>
References: <1345537427-21601-1-git-send-email-mc@linux.vnet.ibm.com>
	<50334B51.6050900@redhat.com> <503357B2.5040901@linux.vnet.ibm.com>
	<CAJSP0QX8BL9R_M0NxisiP+wejjgh6C6-nz9LPAfgHppPpNpYnA@mail.gmail.com>
	<50335F78.1030005@redhat.com> <5034BCD1.9020603@linux.vnet.ibm.com>
	<5034CBF8.3050602@redhat.com>
	<20120822131348.GA3512@stefanha-thinkpad.localdomain>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <virtualization-bounces@lists.linux-foundation.org>
In-Reply-To: <20120822131348.GA3512@stefanha-thinkpad.localdomain>
List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/virtualization>,
	<mailto:virtualization-request@lists.linux-foundation.org?subject=unsubscribe>
List-Archive: <http://lists.linuxfoundation.org/pipermail/virtualization/>
List-Post: <mailto:virtualization@lists.linux-foundation.org>
List-Help: <mailto:virtualization-request@lists.linux-foundation.org?subject=help>
List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/virtualization>,
	<mailto:virtualization-request@lists.linux-foundation.org?subject=subscribe>
Sender: virtualization-bounces@lists.linux-foundation.org
Errors-To: virtualization-bounces@lists.linux-foundation.org
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: zwanp@cn.ibm.com, linuxram@us.ibm.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Cong Meng <mc@linux.vnet.ibm.com>
List-Id: virtualization@lists.linuxfoundation.org

Il 22/08/2012 15:13, Stefan Hajnoczi ha scritto:
> http://lists.gnu.org/archive/html/qemu-devel/2010-12/msg01741.html
> 
> "This is a real problem in practice. IE. the USB CD-ROM on this POWER7
> blade limits transfers to 0x1e000 bytes for example and the Linux "sr"
> driver on the guest is going to try to give me bigger requests than that
> if I don't start limiting them, which will cause all sort of errors."
> 
> It cannot be fixed for emulated SCSI HBAs in general but it can for
> virtio-scsi.

For disks, this should be fixed simply by using scsi-block instead of
scsi-generic.

CD-ROMs are indeed more complicated because burning CDs cannot be done
with syscalls. :/

Paolo