On Tue, May 14, 2013 at 04:14:33PM +0200, Kevin Wolf wrote: > This catches the situation that is described in the bug report at > https://bugs.launchpad.net/qemu/+bug/865518 and goes like this: > > $ qemu-img create -f qcow2 huge.qcow2 $((1024*1024))T > Formatting 'huge.qcow2', fmt=qcow2 size=1152921504606846976 > encryption=off cluster_size=65536 lazy_refcounts=off > $ qemu-io /tmp/huge.qcow2 -c "write $((1024*1024*1024*1024*1024*1024 - > 1024)) 512" > Segmentation fault > > With this patch applied the segfault will be avoided, however the case > will still fail, though gracefully: > > $ qemu-img create -f qcow2 /tmp/huge.qcow2 $((1024*1024))T > Formatting 'huge.qcow2', fmt=qcow2 size=1152921504606846976 > encryption=off cluster_size=65536 lazy_refcounts=off > qemu-img: The image size is too large for file format 'qcow2' > > Note that even long before these overflow checks kick in, you get > insanely high memory usage (up to INT_MAX * sizeof(uint64_t) = 16 GB for > the L1 table), so with somewhat smaller image sizes you'll probably see > qemu aborting for a failed g_malloc(). > > If you need huge image sizes, you should increase the cluster size to > the maximum of 2 MB in order to get higher limits. > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > block/qcow2-cluster.c | 23 +++++++++++++++-------- > block/qcow2.c | 13 +++++++++++-- > block/qcow2.h | 5 +++-- > 3 files changed, 29 insertions(+), 12 deletions(-)
Thanks, applied to my block tree for 1.5: https://github.com/stefanha/qemu/commits/block Stefan
