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<table class="head">
<tr>
<td class="head-ltitle">VIRTIO_BLK(4)</td>
<td class="head-vol">Device Drivers Manual</td>
<td class="head-rtitle">VIRTIO_BLK(4)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">virtio_blk</code> —
<span class="Nd">VirtIO Block driver</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp">To compile this driver into the kernel, place the following lines
in your kernel configuration file:</p>
<div class="Bd Pp Bd-indent"><code class="Cd">device virtio_blk</code></div>
<p class="Pp">Alternatively, to load the driver as a module at boot time, place
the following line in <a class="Xr">loader.conf(5)</a>:</p>
<div class="Bd Pp Bd-indent Li">
<pre>virtio_blk_load="YES"</pre>
</div>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">virtio_blk</code> device driver provides
support for VirtIO block devices.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="LOADER_TUNABLES"><a class="permalink" href="#LOADER_TUNABLES">LOADER
TUNABLES</a></h1>
<p class="Pp">Tunables can be set at the <a class="Xr">loader(8)</a> prompt
before booting the kernel or stored in <a class="Xr">loader.conf(5)</a>.</p>
<dl class="Bl-tag">
<dt id="hw.vtblk.no_ident"><var class="Va">hw.vtblk.no_ident</var></dt>
<dd style="width: auto;"> </dd>
<dt id="hw.vtblk."><var class="Va">hw.vtblk.</var><var class="Ar">X</var><var class="Va">.no_ident</var></dt>
<dd>
<p class="Pp">These tunables disable retrieving the device identification
string from the hypervisor either globally or per-device. The default
value is 0.</p>
</dd>
<dt id="hw.vtblk.writecache_mode"><var class="Va">hw.vtblk.writecache_mode</var></dt>
<dd style="width: auto;"> </dd>
<dt id="hw.vtblk.~2"><var class="Va">hw.vtblk.</var><var class="Ar">X</var><var class="Va">.writecache_mode</var></dt>
<dd>
<p class="Pp">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.</p>
</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="SYSCTL_VARIABLES"><a class="permalink" href="#SYSCTL_VARIABLES">SYSCTL
VARIABLES</a></h1>
<p class="Pp">The following variables are available as
<a class="Xr">sysctl(8)</a> variables.</p>
<dl class="Bl-tag">
<dt id="dev.vtblk."><var class="Va">dev.vtblk.</var><var class="Ar">X</var><var class="Va">.writecache_mode</var></dt>
<dd>
<p class="Pp">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.</p>
</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><a class="Xr">virtio(4)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Nm">virtio_blk</code> driver was written by
<span class="An">Bryan Venteicher</span>
<<a class="Mt" href="mailto:bryanv@FreeBSD.org">bryanv@FreeBSD.org</a>>.
It first appeared in <span class="Ux">FreeBSD 9.0</span>.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">July 2, 2013</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
