From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes. Date: Fri, 8 Mar 2013 10:28:32 +0000 Message-ID: References: <1362653247-32551-1-git-send-email-alex@alex.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Stefano Stabellini Cc: Ian Campbell , Konrad Rzeszutek Wilk , Alex Bligh , Ian Jackson , xen-devel , Jan Beulich List-Id: xen-devel@lists.xenproject.org On Fri, Mar 8, 2013 at 10:17 AM, George Dunlap wrote: >> I would just remove use_o_direct and BDRV_O_NOCACHE altogether > > Wait, aren't O_DIRECT and BDRV_O_NOCACHE required for safety? That > is, without these flags isn't it possible that the guest OS thinks > that the data has made it onto stable storage, while in fact it's > still in dom0's memory? Or am I missing something? And in any case, if it's a kernel bug it should be fixed in the kernel. Alex, which dom0 kernel are you using? I actually seem to recall this being a long-known bug with some versions of the pvops kernels; but I thought it had long since been fixed. Kondrad / IanC, can you comment? Alex, if that's the case and if you're using a distro kernel maybe you should try to push for a backport? -George