From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Novotny Subject: Re: Re: [PATCH] Fix restore handling checks Date: Wed, 23 Jun 2010 14:37:07 +0200 Message-ID: <4C21FFF3.6020302@redhat.com> References: <4C204D8C.3020303@redhat.com> <19488.53018.201328.781032@mariner.uk.xensource.com> <4C21EDA5.5070100@redhat.com> <19489.61339.878715.309115@mariner.uk.xensource.com> <4C21F034.7060501@redhat.com> <20100623133558.57991abf@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100623133558.57991abf@lxorguk.ukuu.org.uk> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Alan Cox Cc: Paolo Bonzini , "'xen-devel@lists.xensource.com'" , Ian Jackson , Keir Fraser List-Id: xen-devel@lists.xenproject.org On 06/23/2010 02:35 PM, Alan Cox wrote: > On Wed, 23 Jun 2010 13:29:56 +0200 > Michal Novotny wrote: > > >> On 06/23/2010 01:27 PM, Ian Jackson wrote: >> >>> Paolo Bonzini writes ("Re: [PATCH] Fix restore handling checks"): >>> >>> >>>> We tried to get that to work, and we could not really find a device >>>> error that worked reliably in the guests. We often got infinite loops >>>> on mount or little after that, on both Linux and Windows. >>>> >>>> >>> That's fine. If the admins don't want that then they can use SCSI or >>> PV or simply not tell the guest to write to the device. >>> >>> Disallowing the configuration entirely just because the error handling >>> is suboptimal (but safe!) is not correct. >>> >>> Ian. >>> >>> >> Why do you think so, Ian? This follows the IDE specifications to >> disallow read-only IDE disks since the specs doesn't support IDE >> read-only disks. The only read-only device being supported by IDE specs >> is the CD-ROM device. >> > IDE (or more properly ATA) doesn't support CD-ROM either. ATAPI does, and > it also supports other ATAPI devices with write protect including magneto > optical and floppy. > > > Agreed Alan. This is right that ATAPI does. Nevertheless in IDE specs it's about ATA and ATAPI. The read-only file systems are supported for IDE drives only for floppy and tape media according to the linux kernel source codes. Also, CD-ROM devices can be read-only but no other IDE media, i.e. no IDE disks. Michal -- Michal Novotny, RHCE Virtualization Team (xen userspace), Red Hat