xref: /dflybsd-src/share/man/man7/vkernel.7 (revision 4af189959268204f4f5efd12b2b5b472f376eca1)

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.\" $DragonFly: src/share/man/man7/vkernel.7,v 1.1 2007/01/08 08:55:44 swildner Exp $
.\"
.Dd January 8, 2007
.Dt VKERNEL 7
.Os
.Sh NAME
.Nm vkernel
.Nd virtual kernel architecture
.Sh SYNOPSIS
.Pa /usr/obj/usr/src/sys/VKERNEL/kernel.debug
.Op Fl e Ar environment
.\".Op Fl i Ar file
.Op Fl m Ar size
.Op Fl r Ar file
.Op Fl v
.Sh DESCRIPTION
The
.Nm
architecture allows for running
.Dx
kernels in userland.
.Pp
The following options are available:
.Bl -tag -width ".Fl m Ar size"
.It Fl e Ar environment
Specify an to be used by the kernel.
The
.Ar environment
argument is a string of the form
.Li name=value:name=value:...
.\".It Fl i Ar file
.\"Specify a memory image
.\".Ar file
.\"to be used by the kernel.
.It Fl m Ar size
Specify the amount of memory to be used by the kernel in bytes,
.Cm K
(kilobytes),
.Cm M
(megabytes) or
.Cm G
(gigabytes).
Lowercase version of
.Cm K , M ,
and
.Cm G
are allowed.
.It Fl r Ar file
Specify the root image
.Ar file
to be used by the kernel.
See
.Sx CONFIGURING AND RUNNING VIRTUAL KERNELS
for further information on how to prepare a root image.
.It Fl v
Turn on verbose booting.
.El
.Sh CONFIGURING AND RUNNING VIRTUAL KERNELS
A couple of steps are necessary in order to prepare the system to build and
run a virtual kernel.
.Ss Setting up the filesystem
The
.Nm
architecture needs a number of files which reside in
.Pa /var/vkernel .
Since these files tend to get rather big and the
.Pa /var
partition is usually of limited size, we recommend the directory to be
created in the
.Pa /home
partition with a link to it in
.Pa /var :
.Bd -literal -offset indent
mkdir /home/var.vkernel
ln -s /home/var.vkernel /var/vkernel
.Ed
.Pp
Next, a filesystem image to be used by the virtual kernel has to be
created:
.Bd -literal -offset indent
dd if=/dev/zero of=/var/vkernel/rootimg.01 bs=1m count=2048
vnconfig -c -s labels vn0 /var/vkernel/rootimg.01
disklabel -r -w vn0 auto
(edit the label to create a vn0a partition)
newfs /dev/vn0a
mount /dev/vn0a /mnt
cpdup / /mnt
umount /mnt
vnconfig -u vn0
.Ed
.Ss Compiling the virtual kernel
In order to compile a virtual kernel use the
.Li VKERNEL
kernel configuration file residing in
.Pa /usr/src/sys/config
(or a configuration file derived thereof):
.Bd -literal -offset indent
cd /usr/src
make buildkernel KERNCONF=VKERNEL
.Ed
.Ss Enabling virtual kernel operation
A special
.Xr sysctl 8 ,
.Va vm.vkernel_enable ,
must be set to enable
.Nm
operation:
.Bd -literal -offset indent
sysctl vm.vkernel_enable=1
.Ed
.Ss Running the kernel
Finally, the virtual kernel can be run:
.Bd -literal -offset indent
cd /usr/obj/usr/src/sys/VKERNEL
\&./kernel.debug -m 64m -r /var/vkernel/rootimg.01
.Ed
.Sh SEE ALSO
.Xr build 7
.Sh HISTORY
Virtual kernels were introduced in
.Dx 1.7 .
.Sh AUTHORS
.An -nosplit
.An Matt Dillon
thought up and implemented the
.Nm
architecture.
This manual page was written by
.An Sascha Wildner .
.Sh BUGS
Virtual kernels are not yet fully operational.