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Re: Interesting qemu/virt-manager bug about the "rotational" attribute o
Re: Interesting qemu/virt-manager bug about the "rotational" attribute on virtio-blk disks
Thu, 16 Jul 2020 11:33:44 +0200
+Cc Michael, Stefan, email@example.com
On Thu, Jul 16, 2020 at 09:06:14AM +0100, Richard W.M. Jones wrote:
> A virtio-blk disk which is backed by a raw file on an SSD,
> inside the guest shows rotational = 1.
> I assumed that qemu must have a "rotational" property for disks and
> this would be communicated by virtio to the guest, but qemu and virtio
> don't seem to have this. Pretty surprising! Is it called something
> other than "rotational"?
I'm not sure if we need to add this property in QEMU, but in Linux
I found these flags (include/linux/blkdev.h) for the block queues:
#define QUEUE_FLAG_NONROT 6 /* non-rotational device (SSD) */
#define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */
xen-blkfront driver is the only one that sets the QUEUE_FLAG_VIRT,
should we do the same in the virtio-blk driver regardless of the backend?