A bit off topic.. converting Linux HVM to PV

[Brad Spencer <brad%anduin.eldar.org@localhost>]

Hello...

I know that this may be a bit off topic for a NetBSD list, but I was
wondering if anyone on the list might know how to do this.  I have a
running Slackware 13.1 64bit HVM running as a HVM DomU with NetBSD 5.1_RC4
as Dom0.  Love the set up quite a bit.  I am looking to convert the Linux
DomU to a full PV DomU and am having quite a bit of trouble.

I think I managed to build a Linux kernel with Xen guest support.  It
claims the following upon trying to 'xm create -c ...':

.
.

Booting paravirtualized kernel on Xen
Xen version: 3.3.2 (preserve-AD)
.
.

So, it would seem to be paravirtulized.  A bit later it does find what
will be the root file system, xvda1:

.
.

List of all partitions:
ca01        16384000 xvda1 driver: vbd
No filesystem could mount root, tried:  romfs
Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(202,1)
Pid: 1, comm: swapper Not tainted 2.6.33.4 #3
Call Trace:
 [<ffffffff8148bd80>] panic+0x78/0x13a
 [<ffffffff81900272>] mount_block_root+0x273/0x29e
 [<ffffffff8190033d>] mount_root+0xa0/0xa4
 [<ffffffff819004b1>] prepare_namespace+0x170/0x1a9
 [<ffffffff818ff759>] kernel_init+0x18c/0x19c
 [<ffffffff8100a264>] kernel_thread_helper+0x4/0x10
 [<ffffffff81009691>] ? int_ret_from_sys_call+0x7/0x1b
 [<ffffffff8148f09d>] ? retint_restore_args+0x5/0x6
 [<ffffffff8100a260>] ? kernel_thread_helper+0x0/0x10
.
.

However, no amount of contortions with the DomU config file allows the
kernel to find the root filesystem.  The guest device xvda1 is mapped to
the filesystem used by the HVM, unmodified:

disk = [ 'file:/lhome2/xen/disks/linux.disk,0x301,w' ]
root = "/dev/xvda1 ro"

I have tried all manor of things instead of 0x301 with the same result.

I suspect that the issue is that the Linux kernel is only trying romfs,
and I really have little idea how to make it try others.  I'v looked at
quite a number of blog and web pages on this topic, including the one on
the NetBSD doc pages, but have not been able to come up with the proper
thing.

Any help would be appreciated.  Thanks in advance.  NetBSD DomU's are
trival to setup in comparison.





-- 
Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS
http://anduin.eldar.org  - & -  http://anduin.ipv6.eldar.org [IPv6 only]