John Snow <js...@redhat.com> writes: > On 08/27/2015 11:29 AM, Eric Blake wrote: >> On 08/27/2015 09:17 AM, Peter Maydell wrote: >>> I've noticed recently that tests/hd-geo-test.c creates test disk >>> images which are 4GB in size, which is a problem if the filesystem >>> on the host doesn't support sparse files. In particular, OSX's HFS+ >>> doesn't have sparse file support, and Windows probably doesn't either. >> >> Windows NTFS supports sparse files (minimum hole size of 64k), but it >> can be a pain to set up, and while it saves disk space, it may actually >> slow your program down. >> >> [At one point cygwin created sparse files on windows by default, but >> because it was demonstrated to hurt performance in dealing with sparse >> files, because Windows doesn't handle sparse files efficiently, the >> cygwin defaults were switched so that it now requires an explicit opt-in >> mount option before even attempting sparse files] >> >>> Worse, if the test fails an assertion somewhere the test doesn't >>> clean up after itself and leaves a 4GB file lying around in /tmp/. >>> >>> It would be nice if we could skip these tests on filesystems that >>> don't have sparse file support... >> >> Or even where sparse files are supported but not default. >> > > Does this test *require* the raw format?
If memory serves, the test doesn't require a specific format, only the size and the contents of the MBR matters. > Use tests/libqos/libqos.c mkqcow2 instead. I'll send a patch. Go right ahead.
