On Wed, May 14, 2014 at 09:27:31AM -0400, Mike Day wrote: > On Wed, May 14, 2014 at 8:35 AM, Stefan Hajnoczi <stefa...@gmail.com> wrote: > > Jeff Cody recently wanted to eliminate duplicate entries in the list. I > > thought part of your intention was to address the duplicates with your > > patch. > > > > We can back out the sequence API if it's not supported on older glib but > > it would be nice to eliminate duplicates later, too. > > I agree. I can submit an additional patch that uses an older API. > What, exactly is the cause of duplicate entries in the list? I've only > seen it one time but its disconcerting when it happens. >
Some block drivers register multiple drivers for a given format name, for instance, gluster: https://github.com/qemu/qemu/blob/master/block/gluster.c#L818 static void bdrv_gluster_init(void) { bdrv_register(&bdrv_gluster_rdma); bdrv_register(&bdrv_gluster_unix); bdrv_register(&bdrv_gluster_tcp); bdrv_register(&bdrv_gluster); } Each of those drivers has a format_name of "gluster", in this example. In qemu-img, it lists the supported formats by simply calling bdrv_iterate_format(), which calls a callback function for each format_name in the driver list. Prior to a recent commit, this function did not make distinction on duplicates. As of commit e855e4fb7, duplicates are not longer printed in the help message: e855e4fb7: Ignore duplicate or NULL format_name in bdrv_iterate_format): https://github.com/qemu/qemu/commit/e855e4fb7b97f7f605e1f44427b98022e39e6f8f#diff-ea36ba0f79150cc299732696a069caba
