xref: /freebsd/usr.sbin/bhyveload/bhyveload.8 (revision 5df041c4bbf70d549b055f332630925295ad5aaf)

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.Dd January 12, 2024
.Dt BHYVELOAD 8
.Os
.Sh NAME
.Nm bhyveload
.Nd load a
.Fx
guest inside a bhyve virtual machine
.Sh SYNOPSIS
.Nm
.Op Fl C
.Op Fl S
.Op Fl c Ar cons-dev
.Op Fl d Ar disk-path
.Op Fl e Ar name=value
.Op Fl h Ar host-path
.Op Fl l Ar os-loader
.Op Fl m Ar memsize Ns Op Ar K|k|M|m|G|g|T|t
.Ar vmname
.Sh DESCRIPTION
.Nm
is used to load a
.Fx
guest inside a
.Xr bhyve 4
virtual machine.
.Pp
.Nm
is based on
.Xr loader 8
and will present an interface identical to the
.Fx
loader on the user's terminal.
This behavior can be changed by specifying a different OS loader.
.Pp
The virtual machine is identified as
.Ar vmname
and will be created if it does not already exist.
.Sh OPTIONS
The following options are available:
.Bl -tag -width indent
.It Fl c Ar cons-dev
.Ar cons-dev
is a
.Xr tty 4
device to use for
.Nm
terminal I/O.
.Pp
The text string "stdio" is also accepted and selects the use of
unbuffered standard I/O. This is the default value.
.It Fl d Ar disk-path
The
.Ar disk-path
is the pathname of the guest's boot disk image.
.It Fl e Ar name=value
Set the
.Fx
loader environment variable
.Ar name
to
.Ar value .
.Pp
The option may be used more than once to set more than one environment
variable.
.It Fl h Ar host-path
The
.Ar host-path
is the directory at the top of the guest's boot filesystem.
.It Fl l Ar os-loader
Specify a different OS loader.
By default
.Nm
will use
.Pa /boot/userboot.so ,
which presents a standard
.Fx
loader.
.It Fl m Ar memsize Ns Op Ar K|k|M|m|G|g|T|t
.Ar memsize
is the amount of memory allocated to the guest.
.Pp
The
.Ar memsize
argument may be suffixed with one of
.Cm K ,
.Cm M ,
.Cm G
or
.Cm T
(either upper or lower case) to indicate a multiple of
Kilobytes, Megabytes, Gigabytes or Terabytes
respectively.
.Pp
.Ar memsize
defaults to 256M.
.It Fl C
Include guest memory in the core file when
.Nm
dumps core.
This is intended for debugging an OS loader as it allows inspection of
the guest memory.
.It Fl S
Wire guest memory.
.El
.Sh EXAMPLES
To create a virtual machine named
.Ar freebsd-vm
that boots off the ISO image
.Pa /freebsd/release.iso
and has 1GB memory allocated to it:
.Pp
.Dl "bhyveload -m 1G -d /freebsd/release.iso freebsd-vm"
.Pp
To create a virtual machine named
.Ar test-vm
with 256MB of memory allocated, the guest root filesystem under the host
directory
.Pa /user/images/test
and terminal I/O sent to the
.Xr nmdm 4
device
.Pa /dev/nmdm1B
.Pp
.Dl "bhyveload -m 256MB -h /usr/images/test -c /dev/nmdm1B test-vm"
.Sh SEE ALSO
.Xr bhyve 4 ,
.Xr nmdm 4 ,
.Xr vmm 4 ,
.Xr bhyve 8 ,
.Xr loader 8
.Sh HISTORY
.Nm
first appeared in
.Fx 10.0 ,
and was developed at NetApp Inc.
.Sh AUTHORS
.Nm
was developed by
.An -nosplit
.An Neel Natu Aq Mt neel@FreeBSD.org
at NetApp Inc with a lot of help from
.An Doug Rabson Aq Mt dfr@FreeBSD.org .
.Sh BUGS
.Nm
can only load
.Fx
as a guest.
.Sh SECURITY CONSIDERATIONS
Note that in some configurations,
.Nm
will execute guest loader scripts in the context of the host machine.
Note, however, that
.Nm
will enter a
.Xr capsicum 4
sandbox before it loads the
.Ar os-loader
or executes any loader scripts.
On the host filesystem, the sandbox will only have access to the path specified
by the
.Fl h
flag, the contents of the
.Pa /boot
directory if
.Fl l
was not specified, and the chosen console device.
.Pp
Note that the guest loader scripts are already subject to some limitations that
are not relaxed simply because we are running in userland.
For instance, any I/O on the loader's
.Dq host
device that can be done in loader scripts is limited to the interface that
.Nm
provides, which itself will restrict paths that can be touched to those within
a specified
.Fl h
directory, if any.
Access to files within
.Pa /boot
inside the sandbox would require arbitrary code execution in userboot, and
userboot is usually provided by the host machine rather than anything that is
a part of the guest image.
All access to the
.Fl h
directory as well as
.Pa /boot
is strictly read-only in the sandbox.