[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH for 4.5] libxl: Tell qemu to use raw format when using a tapdisk
On Tue, 2014-12-09 at 14:04 +0000, George Dunlap wrote: > At the moment libxl unconditinally passes the underlying file format > to qemu in the device string. However, when tapdisk is in use, > tapdisk handles the underlying format and presents qemu with > effectively a raw disk. When qemu looks at the tapdisk block device > and doesn't find the image format it was looking for, it will fail. > > This effectively means that tapdisk cannot be used with HVM domains at > the moment except for raw files. > > Instead, if we're using a tapdisk backend, tell qemu to use a raw file > format. > > Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx> > --- > CC: Ian Campbell <ian.campbell@xxxxxxxxxx> > CC: Ian Jackson <ian.jackson@xxxxxxxxxx> > CC: Wei Liu <wei.liu2@xxxxxxxxxx> > CC: Konrad Wilk <konrad.wilk@xxxxxxxxxx> > > Release exception justification: I agree with your reasoning. > This fixes a bug in functionality, in > that at the moment HVM guests cannot boot with tapdisk and vhd format. > > This is not a regression in xl functionality per se, since (AFAICT) > this has never worked. However, given that 4.5 is the first release > without xend, this *does* represent a regression in functionality for > Xen as a whole (since before people using hvm guest with vhd on blktap > could use xend). > > The fix is very simple and should only affect codepaths that already > don't work, so the risk of regressions should be very low. > > While preparing this patch, I also noticed that cdroms will ignore the > backend parameter and treat everything as a file. This is a bug but I > think it's a much less important one to address this late in the > release cycle. > --- > tools/libxl/libxl_dm.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c > index b25b574..10f3090 100644 > --- a/tools/libxl/libxl_dm.c > +++ b/tools/libxl/libxl_dm.c > @@ -797,11 +797,14 @@ static char ** > libxl__build_device_model_args_new(libxl__gc *gc, > continue; > } > > - if (disks[i].backend == LIBXL_DISK_BACKEND_TAP) > + if (disks[i].backend == LIBXL_DISK_BACKEND_TAP) { > + format = qemu_disk_format_string(LIBXL_DISK_FORMAT_RAW); > pdev_path = libxl__blktap_devpath(gc, disks[i].pdev_path, > disks[i].format); > - else > + } else { > pdev_path = disks[i].pdev_path; > + } > + > > /* > * Explicit sd disks are passed through as is. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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