virtio_blk — VirtIO Block driver

       The virtio_blk device driver provides support for VirtIO block devices.

       The virtio_blk driver was written  by  Bryan  Venteicher  <bryanv@FreeBSD.org>.   It  first  appeared  in
       FreeBSD 9.0.

Debian                                            July 2, 2013                                     VIRTIO_BLK(4)

       Tunables can be set at the loader(8) prompt before booting the kernel or stored in loader.conf(5).

       hw.vtblk.no_identhw.vtblk.X.no_ident

               These  tunables  disable  retrieving  the device identification string from the hypervisor either
               globally or per-device.  The default value is 0.

       hw.vtblk.writecache_modehw.vtblk.X.writecache_mode

               These tunables determine the write cache mode globally or per-device.  The mode can changed  only
               if  the  ConfigWCE  feature is negotiated.  Set to 0 for writethrough mode, 1 for writeback mode,
               and -1 to leave it as-is.  The default value is to leave as-is.

       virtio_blk — VirtIO Block driver

virtio(4)

       To compile this driver into the kernel, place the following lines in your kernel configuration file:

             devicevirtio_blk

       Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

             virtio_blk_load="YES"

       The following variables are available as sysctl(8) variables.

       dev.vtblk.X.writecache_mode

               The write cache mode of the device can be either writethrough  (0)  or  writeback  (1).   If  the
               ConfigWCE  feature  is  negotiated,  the write cache mode can be toggled between writethrough and
               writeback.