Re: [Xen-users] Booting FreeBSD diskless in DomU

[Geoff Buckingham <geoffb@xxxxxxxxxxxxxxxxxxx>]

On Thu, Sep 08, 2005 at 09:36:08PM +0000, Geoff Buckingham wrote:
> On Thu, Sep 08, 2005 at 11:42:29AM -0700, Kip Macy wrote:
> > I vaguely recall disabling xenFreeBSD's diskless support. One alternative 
> > is 
> > to have a small loopback mounted root with the majority of your files 
> > exported over NFS.
> > 
> It seems odd that it hangs in the bpf initialisation though.
> 
> When you say you disabled xenFreeBSD's diskless support, is it missing an 
> option NFSROOT in the kernel or has the code gone?
> 

To answer my own question for the sake of the archive, to boot diskless
FreeBSD DomU environment you need to follw Kip Macey's instuctions with a
few changes:

Download and extract the xen 2.0.7 source tarball.
Download FreeBSD 5.3 source. I was able to use a cvsup of RELENG_5_3 which
incorporates the security fixes since 5.3 RELEASE.
I used the i386-xeno.tgz source from

http://www.fsmware.com/xenofreebsd/5.3/050123/i386-xeno.tgz

ther may be a more recent tarball...this worked so far.

Building the current image:
1) on a machine running FreeBSD 5.3 download i386-xeno.tgz
kmacy@freebird cd /sys
kmacy@freebird tar xzf ~/i386-xeno.tgz 
kmacy@freebird cd conf
(assumes csh)
kmacy@freebird foreach file ( ../i386-xeno/sys/conf/*.i386-xeno )
foreach? ln -s $file
kmacy@freebird cd ../i386-xeno/conf/

Edit XENCONF, uncomment "options NFS_ROOT" and add the following:

               options BOOTP
               options BOOTP_NFSROOT
               options BOOTP_COMPAT

As I had some issues compiling agp kernel modules I didn't need I suggest you
edit /etc/make.conf and add 'NO_MODULES="YES"'

# create compile directory
kmacy@freebird config XENCONF 
Kernel build directory is ../compile/XENCONF
Don't forget to do a ``make depend''
kmacy@freebird cd ../../include/
# link in xen interface headers
kmacy@freebird ln -s <PATH to your XEN source>/xen/include/public hypervisor-ifs
kmacy@freebird cd ../compile/XENCONF
kmacy@freebird make kernel-depend
# build kernel
kmacy@freebird make -j4 kernel
<...>
linking kernel.debug
   text    data     bss     dec     hex filename
2057881  135964  179472 2373317  2436c5 kernel.debug
objcopy --strip-debug kernel.debug kernel 

The kernel you get is only realy any good for diskless use but needs no extra
kenv arguments passed to it. It will pick up NFS server and path from a DHCP
or BOOTP server. (i.e. you can comment out all the 'extra' string definitions
in freebsd.phy

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