> > Add a new option "secdiscard" for block drive. Parse it and record it > > in bs->open_flags as bit(BDRV_O_SECDISCARD). > > > > Add a new BDRV_REQ_SECDISCARD bit for secure discard request from > > virtual device. > > > > For host_device backend: implement by ioctl(BLKSECDISCARD) on real > > host block device. > > For other backend, no implementation. > > > > E.g.: > > qemu-system-x86_64 \ > > ... \ > > -drive > file=/dev/mmcblk0p2,if=none,format=raw,discard=on,secdiscard=on,id=sd0 \ > > -device virtio-blk-pci,drive=sd0,id=sd0_vblk \ > > ... > > I'm curious why there is explicit control over this feature (-drive > secdiscard=on|off). For example, is there a reason why users would want to > disable secdiscard on a drive that supports it? I guess there is no way to > emulate > it correctly so secdiscard=on on a drive that doesn't support it produces an > error?
Yes. AFAIK, there is no way to emulate a "secure" discard. But it seems also hard to detect whether a host drive support secdiscard unless it really perform a real secdiscard. So I choose to add an option for user to enable it for virtual block. There is an assumption that user knows whether host support secdiscard. Best Regard Yadong
