Re: [Xen-users] Convert "full virtual" xenU to "paravirtual" (SOLVED)

[James Drenter <jdrenter@xxxxxxxxxxxxx>]

That did it.  Many, many thanks!

After doing the mkinitrd to include xenblk, it worked fine.  I should further 
note that the extra step of modifying /etc/modprobe.conf to contain just:
alias eth0 xennet
alias scsi_hostadapter xenblk

Per Fajar's response was not necessary for things to work, but it did also seem 
to work OK.  I also found a note about doing this at 
https://virt.108.redhat.com/articles/2007/01/15/rhel4-testing.html.  It is 
possible not doing it may cause a problem with some part of the OS I'm not 
using, so it is probably worth mentioning.

I was able to remove "type=ioemu" from the vif line without any ill effects.  I was also 
able to completely remove the "root = ..." line.

Thank you again,
James

Jason Solan wrote:
> I have not tried this on RHEL5 yet, but I have done it successfully on
> Fedora.
>
> Along with installing the xen kernel on the guest with yum, I had to
> recreate the initrd and include the xenblk module.
>
> mkinitrd -f --preload=xenblk /boot/initrd.<kernel_version>.xenblk.img
> <kernel_version>
>
> After that I modified the grub config of the guest (assuming you're
> using pygrub) to make use of the new initrd.
>
>
> My steps in short form:
>   Install HVM guest
>   Boot into HVM guest
>   Install xen kernel from within HVM guest
>   Recreate initrd from within HVM guest
>   Modify grub.conf of HVM guest to point to the new initrd.
>   Shutdown HVM guest
>   Modify HVM config on dom0 to be a PV config file (remove
> hvmloader/device_model and add in pygrub like you have.  I think i also
> removed type=ioemu from the vif line)
>   xm create on the modified config (use -c to choose which kernel to
> boot)
>
>
> Hope that helps.  If its not clear let me know.  I planned to make a
> detailed guide (for this as well as converting PV to HVM) for my own
> use, but haven't had time yet.
>
> On Wed, 2007-09-26 at 14:33 -0400, James Drenter wrote:
> > I'm stuck in a position where I need to be able to convert (in situ) a fully 
> > virtualized xenU to a paravirtualized xenU.  I've seen this discussed a few 
> > times in a few places, but I've never seen a good discussion of it actually 
> > being done.  It always seems like some workaround is put into place.  My 
> > options are extremely limited so that isn't really feasible for me.
> >
> > Here's the situation:
> > I have a single RHEL5 system (64-bit) with plenty of memory and hard drive 
> > space with Xen 3.0.3 installed.  While I have root access and can reboot this 
> > system, I do not have access to the system console (it sits in an inaccessible 
> > data center).
> >
> > On this system, I need to host 4 paravirtualized xenU's running 64-bit RHEL 4 & 
> > 5.  Still all well and good.
> >
> > Now it starts to get tricky:  I need to install these systems from prepared ISO 
> > images.  There does not seem to be any way to directly install a 
> > paravirtualized domain from ISOs, only a fully virtualized domain (HVM).  I've 
> > been able to install HVM domUs, but now performance is an issue and I'd really 
> > like to convert them to paravirtualized domUs.  I can't seem to make it work.
> >
> > I've got the xenU kernel in place and changed the original /etc/xen/vm.cfg file 
> > from:
> > name = "vm1"
> > builder = "hvm"
> > memory = "1000"
> > disk = [ 'phy:/dev/VolGroupVMa/LogVol03,hda,w', ]
> > vif = [ 'type=ioemu, mac=00:16:3e:1a:19:29, bridge=xenbr0', ]
> > uuid = "7c3cc0d6-9135-714e-df58-d85e16136d29"
> > device_model = "/usr/lib64/xen/bin/qemu-dm"
> > kernel = "/usr/lib/xen/boot/hvmloader"
> > vnc=1
> > vncunused=1
> > apic=1
> > acpi=1
> > pae=1
> > vcpus=2
> > serial = "pty" # enable serial console
> > on_reboot   = 'restart'
> > on_crash    = 'restart'
> >
> > To:
> > name = "vm1"
> > memory = "1000"
> > disk = [ 'phy:/dev/VolGroupVMa/LogVol03,hda,w', ]
> > vif = [ 'type=ioemu, mac=00:16:3e:1a:19:29, bridge=xenbr0', ]
> > uuid = "33983d8f-5235-155f-719c-0a0ca299a7a7"
> > bootloader = "/usr/bin/pygrub"
> > root = "/dev/hda1 rw"
> > vnc=1
> > vncunused=1
> > vcpus=2
> > on_reboot   = 'restart'
> > on_crash    = 'restart'
> >
> > Everytime I try to start the xenU domain (xm create vm1), it looks like it is 
> > going to work, then dies after a couple of seconds.  The output is not very 
> > helpful:
> > Using config file "./vm4".
> > Going to boot Red Hat Enterprise Linux AS (2.6.9-55.ELxenU)
> >  kernel: /boot/vmlinuz-2.6.9-55.ELxenU
> >  initrd: /boot/initrd-2.6.9-55.ELxenU.img
> > Started domain vm4
> > xen_start_info @ffffffff80818000
> > shared @m0000275000 @ffffffff80107000=@ffffffffff5fd000 [0x802]
> > xen_start_info: @ffffffff80818000
> > cr3 0000000000101000 pml4p ffffffff80101ff8
> > pml4e 0000000000103067 (real 000000012a711067) pgdp ffffff8000103ff0
> > pgde 0000000000105067 (real 000000012a667067) pmdp ffffff8000105020
> > pmde 0000000000822067 (real 000000012a9ca067) ptep ffffff80008220c0
> > pte 0010000000818027 (real 001000012a9d4027)
> > xen_shared_info: @ffffffffff5fd000
> > cr3 0000000000101000 pml4p ffffffff80101ff8
> > pml4e 0000000000103067 (real 000000012a711067) pgdp ffffff8000103ff8
> > pgde 0000000000000000 is none
> > PAGE_OFFSET+1.2: @ffffff8000001000
> > cr3 0000000000101000 pml4p ffffffff80101ff8
> > pml4e 0000000000103067 (real 000000012a711067) pgdp ffffff8000103000
> > pgde 0000000000824067 (real 000000012a9c8067) pmdp ffffff8000824000
> > pmde 0000000000825067 (real 000000012a9c7067) ptep ffffff8000825008
> > pte 0000000000001167 (real 000000012a643167)
> > rtc: IRQ 8 is not free.
> > i8042.c: No controller found.
> > Kernel panic - not syncing: Attempted to kill init!
> >
> > That's it, it stops there.
> >
> > My experience with XEN is limited, so I know I might be doing something 
> > completely wrong.  Any help would be greatly appreciated.
> >
> > Regards,
> > James
> >
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
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