[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC] libxl: relax readonly check introduced by XSA-142 fix
On Thu, 2015-11-12 at 10:53 -0700, Jim Fehlig wrote: > Ian Campbell wrote: > > On Thu, 2015-11-12 at 08:45 -0700, Jim Fehlig wrote: > > > Â > > > > The commit message doesn't say anything about AHCI. Are AHCI disks > > > > actually emulated correctly by QEMU with readonly=on? > > > I just double checked, and good thing since AHCI + readonly is > > > another > > > rejected > > > combination > > > > > > /usr/lib/xen/bin/qemu-system-i386 -device ahci,id=ahci0 \ > > > Â-drive file=/tmp/disk.raw,if=none,id=ahcidisk- > > > 0,format=raw,readonly=on \ > > > Â-device ide-hd,bus=ahci0.0,unit=0,drive=ahcidisk-0 > > > qemu-system-i386: -device ide-hd,bus=ahci0.0,unit=0,drive=ahcidisk-0: > > > Can't use > > > a read-only drive > > > > > > So IDE/SATA/AHCI are all incompatible with readonly=on. I'll fix this > > > and > > > ammend > > > the commit message in V2. > > > > Just to clarify when you say "rejected" and "incompatible" do you mean > > that > > qemu will fail to start if you try, or that it will ignore you and give > > a > > writeable disk? > > qemu will fail to start. OK, that's good, I was a bit worried it might fail open. > > If, as I think, it will fail, why don't we just always ask and rely on > > qemu > > to reject, instead of trying to whitelist the ones we know work in the > > libxl code? > > That would be possible, but makes it more difficult to track down why the > domain > failed to start.[...] Indeed. > libxl: error: libxl_create.c:1340:domcreate_devmodel_started: device model did > not start: -6 At a minimum this ought to do as the bootloader failed message does and say "look inÂ/var/log/xen/qemu-dm-sles12-hvm.log for more info". Ideally error reporting from qemu back to the toolstack would be able to actually report back what was going on somehow (which I appreciate might be rather difficult to arrange). Anyway, none of that is on you and since qemu fails safe if libxl gets it wrong I don't think it should block this patch. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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