blog/content/2014/10/building-bhyve-images-using-makefs-and.html

---
title: Building bhyve Images using makefs and mkimg
description: >
  A walk through on building bootable images that do not require the user to be root.
posted: !!timestamp '2014-10-29'
created: !!timestamp '2014-10-29'
time: 8:57 PM
tags:
  - bhyve
  - FreeBSD
---

Recently Neel Natu [committed](https://svnweb.freebsd.org/changeset/base/r273375)
work to enable bhyve to run on AMD processors.  My main development
machine is an AMD A10-5700, so the commit enables me to use bhyve for
testing.

EDIT: Anish Gupta did the work that Neel Natu committed.  Thanks Anish!

I had previously built images using `makefs` and `mkimg` for a CF card for
use in another machine, so being able to build images to use with bhyve
makes sense.

First, you need to make sure that you have a complete source check out
along with a completed buildworld and buildkernel.  Then follow these steps:

1.  Install world and distribution into a temporary directory using the `NO_ROOT` option:
    <pre class="fullwidth"><code>
    make installworld DESTDIR=&lt;tmpdir&gt; -DDB_FROM_SRC -DNO_ROOT
    make distribution DESTDIR=&lt;tmpdir&gt; -DDB_FROM_SRC -DNO_ROOT
    </code></pre>
    This preps everything with the defaults as necessary.
2.  Install a kernel either into a different directory (I do this) or into the same directory above:
    <pre class="fullwidth"><code>
    make installkernel DESTDIR=&lt;tmpkerndir&gt; -DNO_ROOT KERNCONF=&lt;conf&gt;
    </code></pre>
3.  Make a directory with your custom configuration files.  The basics
    are `/etc/rc.conf` and `/etc/fstab` and you might want `/firstboot` on
    there too.  You will also need a `METALOG` file which contains the
    permissions for the files.  This is just a standard `mtree` file, so
    you could use `mtree` to generate this instead of creating it by hand.
    The file contents are below.
4.  Build the ufs image using the `makeroot.sh` script in the src tree at `tools/tools/makeroot/makeroot.sh`:
    <pre class="fullwidth"><code>
    /usr/src/tools/tools/makeroot/makeroot.sh  -e &lt;custdir&gt;/METALOG -e &lt;tmpkerndir&gt;/METALOG -p &lt;tmpdir&gt;/etc/master.passwd -s 2g ufs.img root
    </code></pre>
5.  Build the disc image:
    <pre class="fullwidth"><code>
    mkimg -s gpt -b &lt;tmpdir&gt;/boot/pmbr -p freebsd-boot:=&lt;tmpdir&gt;/boot/gptboot -p freebsd-swap::1G -p freebsd-ufs:=ufs.img -o disc.img
    </code></pre>
6.  Run the image:
    <pre class="fullwidth"><code>
    sh /usr/share/examples/bhyve/vmrun.sh -d disc.img vm0
    </code></pre>

There you have it.   Besides running the image, all the other steps can
be done as a normal user w/o root access.

EDIT: You also might want to include an `/entropy` file (populated with 4k
from `/dev/random`) in your custom directory so that the image has a good
seed for entropy at first boot for things such as sshd key generation.

File contents:

* `/etc/fstab`:
  <pre class="fullwidth"><code>
  /dev/vtbd0p3    /               ufs     rw              1 1
  </code></pre>
* Custom `METALOG`:
  <pre class="fullwidth"><code>
  #mtree 2.0
  ./etc/rc.conf type=file uname=root gname=wheel mode=0644
  ./etc/fstab type=file uname=root gname=wheel mode=0644
  ./firstboot type=file uname=root gname=wheel mode=0644
  </code></pre>