NAME

     virtio_blk — VirtIO Block driver

SYNOPSIS

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

           device virtio_blk

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

           virtio_blk_load="YES"

DESCRIPTION

     The virtio_blk device driver provides support for VirtIO block devices.

LOADER TUNABLES

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

     hw.vtblk.no_ident

     hw.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_mode

     hw.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.

SYSCTL VARIABLES

     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.

SEE ALSO

     virtio(4)

HISTORY

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