On Thu, 6 Feb 2014, Olaf Hering wrote: > @@ -253,6 +254,8 @@ static int ioreq_parse(struct ioreq *ioreq) > case BLKIF_OP_WRITE: > ioreq->prot = PROT_READ; /* from memory */ > break; > + case BLKIF_OP_DISCARD: > + return 0; > default: > xen_be_printf(&blkdev->xendev, 0, "error: unknown operation (%d)\n", > ioreq->req.operation);
Unfortunately I didn't realize before that older Xen releases don't define BLKIF_OP_DISCARD, therefore this patch would cause QEMU build failures against Xen 4.1 for example. Give a look at include/hw/xen/xen_common.h to see how compatibility with older Xen versions is usually achieved in QEMU.
