Xen users - Jun 2012 - HVM vs PV - conversion

Greetings,

I would like to know how one can identify if a DomU is PV or HVM? Any docs
which may indicate a way to find out?

I have a CentOS 5.5 64bit DomU which might be HVM - how can this DomU can
be made PV?
Just stop the DomU, and then delete it using Virtual Machine Manager and
the create another config file for a PV DomU and use xm new and then xm
start?

Let''s say I have a config file like: [for a HVM DomU]

VMHOST1 /]# more /etc/xen/DBS1
name = "DBS1"
uuid = "904ec14c-9a46-3dae-ee7a-16470c5f5ef5"
maxmem = 4096
memory = 2048
vcpus = 2
builder = "hvm"
kernel = "/usr/lib/xen/boot/hvmloader"
boot = "c"
pae = 1
acpi = 1
apic = 1
localtime = 0
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
device_model = "/usr/lib64/xen/bin/qemu-dm"
sdl = 0
vnc = 1
vncunused = 0
vncdisplay = 53290
keymap = "en-us"
disk = [ "phy:/dev/VG1/DBS1,hda,w" ,
"phy:/dev/VG2/DBR,hdb,w",
"phy:/dev/VG2/DBR_backup,hdc,w" ]
vif = [ "mac=00:16:36:0a:aa:69,bridge=eth4,script=vif-bridge" ]
parallel = "none"
serial = "pty"

Just changing the config file to something like:

VMHOST1 /]# more /etc/xen/DBS2a
name = "DBS2a"
maxmem = 4096
memory = 2048
vcpus = 2
cpus = "1-7"
bootloader = "/usr/bin/pygrub"
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
vfb = [ "type=vnc,vncunused=1,keymap=en-us" ]
disk = [ "phy:/dev/VG1/DBS2a,xvda,w" ,
"phy:/dev/VG2/DBR2,xvdb,w" ,
"phy:/dev/VG2/DBR2_backup,xvdc,w" ]
vif = [ "mac= 00:16:36:0a:aa:69,bridge=eth4" ]

will create a PV DomU? [xm new DBS2a , xm start DBS2a]

Is it a way to convert a config.sxp into a "xm" config file like the
one
above?

Thank you for your help!

Frank


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On Sun, 2012-06-10 at 06:48 +0100, fpt stl wrote:
> Greetings,
> 
> 
> I would like to know how one can identify if a DomU is PV or HVM? Any
> docs which may indicate a way to find out?
tools/misc/xen-detect.c in the Xen source contains code which can do
this. You mght also find virt-what
( people.redhat.com/~rjones/virt-what ) useful.
> I have a CentOS 5.5 64bit DomU which might be HVM - how can this DomU
> can be made PV?
> Just stop the DomU, and then delete it using Virtual Machine Manager
> and the create another config file for a PV DomU and use xm new and
> then xm start?
> 
> 
> Let''s say I have a config file like: [for a HVM DomU]
[...]
> 
> Just changing the config file to something like:
> 
[...]

"Something" like that, yes (I mean it looks correct at a first
glance).

You''d want to ensure that the in-guest grub configuration pointed to a
Xen PV aware kernel. An easier first pass might be to use the dom0
kernek with  kernel=/ramdisk=/extra= instead of bootloader=.
> Is it a way to convert a config.sxp into a "xm" config file like
the
> one above?
Other than by hand I don''t know of one.

Ian.