From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53394) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T4TlX-0005lA-Uf for qemu-devel@nongnu.org; Thu, 23 Aug 2012 05:31:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T4TlW-0005C4-O7 for qemu-devel@nongnu.org; Thu, 23 Aug 2012 05:31:51 -0400 Received: from e28smtp04.in.ibm.com ([122.248.162.4]:36223) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T4TlW-0005B6-4N for qemu-devel@nongnu.org; Thu, 23 Aug 2012 05:31:50 -0400 Received: from /spool/local by e28smtp04.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 23 Aug 2012 15:01:44 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q7N9VeOY61997188 for ; Thu, 23 Aug 2012 15:01:41 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q7N9VbhP018096 for ; Thu, 23 Aug 2012 19:31:39 +1000 Message-ID: <5035F873.6090305@linux.vnet.ibm.com> Date: Thu, 23 Aug 2012 17:31:31 +0800 From: Cong Meng MIME-Version: 1.0 References: <1345537427-21601-1-git-send-email-mc@linux.vnet.ibm.com> <50334B51.6050900@redhat.com> <503357B2.5040901@linux.vnet.ibm.com> <50335F78.1030005@redhat.com> <5034BCD1.9020603@linux.vnet.ibm.com> <5034CBF8.3050602@redhat.com> <20120822131348.GA3512@stefanha-thinkpad.localdomain> <5034E918.4030305@redhat.com> In-Reply-To: <5034E918.4030305@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/2 v1] blkdrv: Add queue limits parameters for sg block drive List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Stefan Hajnoczi , Stefan Hajnoczi , zwanp@cn.ibm.com, linuxram@us.ibm.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org On Wed 22 Aug 2012 10:13:44 PM CST, Paolo Bonzini wrote: > 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. :/ > So, as the problem exist to CD-ROM, I will continue to get these patches move on. As Paolo pointed out, the only limit is max_sectors (the total size of a scatter-list), I will drop the other 2 parameters. Paolo, what's your opinion? Cong > Paolo >