Alvaro Karsz
2022-Sep-28 10:48 UTC
[PATCH v3] virtio_blk: add SECURE ERASE command support
> What I worry about is that down the road we might want to add > special meaning to currently unused values. > If doing that just clears VIRTIO_BLK_F_SECURE_ERASE then > we have forward compatibility. If it fails probe then we > won't be able to do use these values.They are not exactly unused, we are using them to calculate the "discard sector alignment" and the "max discard sectors" values. The values are even used directly if VIRTIO_BLK_F_DISCARD is not negotiated.
Michael S. Tsirkin
2022-Sep-28 13:15 UTC
[PATCH v3] virtio_blk: add SECURE ERASE command support
On Wed, Sep 28, 2022 at 01:48:43PM +0300, Alvaro Karsz wrote:> > What I worry about is that down the road we might want to add > > special meaning to currently unused values. > > If doing that just clears VIRTIO_BLK_F_SECURE_ERASE then > > we have forward compatibility. If it fails probe then we > > won't be able to do use these values. > > > They are not exactly unused, we are using them to calculate the > "discard sector alignment" and the "max discard sectors" values. > The values are even used directly if VIRTIO_BLK_F_DISCARD is not negotiated.Could you explain this last part? Why are they used without VIRTIO_BLK_F_DISCARD? -- MST