From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antoine Martin Subject: Re: raw disks no longer work in latest kvm (kvm-88 was fine) Date: Sun, 23 May 2010 21:07:55 +0700 Message-ID: <4BF936BB.5000401@nagafix.co.uk> References: <4B92BF97.4040001@nagafix.co.uk> <4B92C90B.4030807@msgid.tls.msk.ru> <4B932829.8090503@nagafix.co.uk> <4B9372B6.3050408@msgid.tls.msk.ru> <20100307100022.GA23201@infradead.org> <4B93A624.8010707@nagafix.co.uk> <4B93AF8A.3070805@nagafix.co.uk> <4B93C2F9.7030904@msgid.tls.msk.ru> <4B93DE3F.4090103@nagafix.co.uk> <4B93DFF0.5050905@redhat.com> <20100307172151.GA24859@infradead.org> <4B93E29E.6090609@redhat.com> <4B93E9EE.6020701@nagafix.co.uk> <4B93F4A4.9050003@redhat.com> <4B93F96E.30508@nagafix.co.uk> <4B93FA18.2090808@redhat.com> <4B93FAD8.9010207@nagafix.co.uk> <4B93FBC1.3000209@redhat.com> <4B93FD94.7060508@nagafix.co.uk> <4B93FFEE.4080007@redhat.com> <4B9B6008.4090902@nagafix.co.uk> <4BBE51F4.6070904@nagafix.co.uk> <4BF7B589.1070808@nagafix.co.uk> <4BF7BD33.2090700@msgid.tls. msk.ru> <4BF7C172.2000508@nagafix.co.uk> <4BF8ED0C.2070004@nagafix.co.uk> <4BF91844.8030903@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Michael Tokarev , Christoph Hellwig , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mamba.nagafix.co.uk ([194.145.196.68]:48167 "EHLO mail.nagafix.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754704Ab0EWOIK (ORCPT ); Sun, 23 May 2010 10:08:10 -0400 In-Reply-To: <4BF91844.8030903@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 05/23/2010 06:57 PM, Avi Kivity wrote: > On 05/23/2010 11:53 AM, Antoine Martin wrote: >> I'm not: 64-bit host and 64-bit guest. >> Just to be sure, I've tested that patch and still no joy: >> /dev/vdc: read failed after 0 of 512 at 0: Input/output error >> /dev/vdc: read failed after 0 of 512 at 0: Input/output error >> /dev/vdc: read failed after 0 of 2048 at 0: Input/output error >> pread is still broken on this big raw disk. >> > > Can you summarize your environment and reproducer again? The thread > is so long it is difficult to understand exactly what you are testing. > Sure thing: Description of the problem: A guest tries to mount a large raw partition (1.5TB /dev/sda9 in my case), this fails with pread enabled, works with it disabled. What has been tested: Host has had 2.6.31.x and now 2.6.34 - with no improvement. Guest has had numerous kernel versions and patches applied for testing (from 2.6.31.x to 2.6.34) - none made any difference. (although the recent patch stopped the large partition from getting corrupted by the merged requests bug.. yay!) It was once thought that glibc needed to be rebuilt against newer kernel headers, done that too, and rebuilt qemu-kvm afterwards. (was 2.6.28 then 2.6.31 and now 2.6.33) What has been reported: straces, kernel error messages as above. Here is the qemu command line (sanitized - removed the virtual disks which work fine and network config): qemu -clock dynticks -m 256 -L ./ -kernel ./bzImage-2.6.34-aio -append "root=/dev/vda" -nographic -drive file=/dev/sda9,if=virtio,cache=none Let me know if you need any other details. I can also arrange ssh access to the system if needed. Cheers Antoine