Commit 090fa1c8 "add support for unplugging NVMe disks..." extended the
existing disk unplug flag to cover NVMe disks as well as IDE and SCSI.
The recent thread on the xen-devel mailing list [1] has highlighted that
this is not desirable behaviour: PV frontends should be able to distinguish
NVMe disks from other types of disk and should have separate control over
whether they are unplugged.
This patch defines a new bit in the unplug mask for this purpose (see Xen
commit [2]) and also tidies up the definitions of, and improves the
comments regarding, the previously exiting bits in the protocol.
[1] https://lists.xen.org/archives/html/xen-devel/2017-03/msg02924.html
[2] http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=1096aa02
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
04d6da4ff6