From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55473) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d6fqP-0000YA-7r for qemu-devel@nongnu.org; Fri, 05 May 2017 12:12:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d6fqM-00030P-2n for qemu-devel@nongnu.org; Fri, 05 May 2017 12:12:37 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58584 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d6fqL-00030B-TI for qemu-devel@nongnu.org; Fri, 05 May 2017 12:12:34 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v45G4D7Z039590 for ; Fri, 5 May 2017 12:12:32 -0400 Received: from e37.co.us.ibm.com (e37.co.us.ibm.com [32.97.110.158]) by mx0b-001b2d01.pphosted.com with ESMTP id 2a8qm2r1pn-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 05 May 2017 12:12:32 -0400 Received: from localhost by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 5 May 2017 10:12:31 -0600 References: <20170426144645.12476-1-farman@linux.vnet.ibm.com> <20170505074143.GB21435@lemon.lan> <298bd169-6f9f-e622-1b8b-85ef126d8d0c@linux.vnet.ibm.com> From: Eric Farman Date: Fri, 5 May 2017 12:12:26 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Message-Id: Subject: Re: [Qemu-devel] [RFC PATCH v1 0/5] Enable virtio-scsi boot from /dev/sgX List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Fam Zheng Cc: "Michael S . Tsirkin" , Alexander Graf , qemu-devel@nongnu.org, Christian Borntraeger , Cornelia Huck On 05/05/2017 11:13 AM, Paolo Bonzini wrote: > > > On 05/05/2017 17:03, Eric Farman wrote: >> We get a value of x3fffff when sending that to a scsi-disk from bios >> code. That's fully emulated though, in scsi_disk_emulate_inquiry. And >> that's the scenario that already works. >> >> While there is indeed code in hw/scsi/scsi-generic.c to wire that in, >> that only happens after the I/O goes to the device itself. The Block >> Limits page isn't supported [1] and thus it gets rejected with "invalid >> field in cdb". We never get to that fixup code you reference, since the >> returned len is zero. >> >> Should I be refactoring this code to always patch in that block limit >> regardless of a response from the host/device? (That is, when page xb0 >> isn't supported by the hw.) > > What is the BLKSECTGET value you get? x140000 bytes when using /dev/sg0 (xa00 sectors when using /dev/sda). > Is there a sensible default value > that you can use when page 0xb0 isn't supported by the hardware? I was setting max_sectors to x800 with good success, which was the power-of-2 floor that BLKSECTGET gave us. That kept us within the limits of the host biovec code. But it's a long way from the virtio-scsi value of xFFFF when max_sectors isn't specified, so don't know what side effects that may cause. > > Thanks, > > Paolo >