Re: [Xen-devel] Xen Dom U kernel

I don't have any issues using my dom0 kernel & initrd to boot pv domU,config has CONFIG_XEN_BLKDEV_FRONTEND=m as well.

However, thats when passing through file based images & LVM from thedom0 to the domU. Is this more of an issue when LVM is implemented onthe domU itself??? That's what I am seeing here. Should he be adding abreak=premount option to initrd and checking visibility of the LVM rootfrom busybox?



Pasi Kärkkäinen wrote:

On Mon, Apr 19, 2010 at 12:08:35PM -0700, kishore kumar wrote:

   I included
   kernel = "/boot/vmlinuz-2.6.32.10"
   ramdisk = "/boot/initrd-2.6.32.10.img" (This is the same as my Dom 0.  As
   I am trying to boot the same Dom 0 as my Dom U without any changes)


You cannot use the dom0 initrd/ramdisk for domU!

dom0 initrd contains drivers for the physical hardware, while in the domU initrd
you need to have drivers for the _virtual_ hardware!

In the log below root was not found because the drivers for the xen block 
devices
are not loaded.

-- Pasi

   disk = ['phy:sda2,sda2,w']
   root= "/dev/VolGroup01/LogVol00 ro"

     I see my .config and I have
   CONFIG_XEN_BLKDEV_FRONTEND=m
   CONFIG_XEN_BLKDEV_BACKEND=y
   CONFIG_XEN_BACKEND=y

   Below is the output pasted.  Any help please on what is going wrong here?

   XENBUS: Device with no driver: device/vbd/2050

   XENBUS: Device with no driver: device/vif/0

   XENBUS: Device with no driver: device/console/0

   Magic number: 1:252:3141

   drivers/rtc/hctosys.c: unable to open rtc device (rtc0)

   Initalizing network drop monitor service

   Freeing unused kernel memory: 3392k freed

   Write protecting the kernel read-only data: 6912k

   Red Hat nash version 5.1.19.6 starting

   Mounting proc filesystem

   Mounting sysfs filesystem

   Creating /dev

   Creating initial device nodes

   Setting up hotplug.

   Creating block device nodes.

   Loading ehci-hcd.ko module

   ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver

   insmod used greatest stack depth: 5712 bytes left

   Loading ssb.ko module

   Loading ohci-hcd.ko module

   ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver

   Loading uhci-hcd.ko module

   uhci_hcd: USB Universal Host Controller Interface driver

   Scanning and configuring dmraid supported devices

   Scanning logical volumes

   Reading all physical volumes. This may take a while...

   lvm used greatest stack depth: 5328 bytes left

   Activating logical volumes

   Volume group "VolGroup01" not found

   Trying to resume from /dev/VolGroup01/LogVol01

   Unable to access resume device (/dev/VolGroup01/LogVol01)

   Creating root device.

   Mounting root filesystem.

   mount: could not find filesystem '/dev/root'

   Setting up other filesystems.

   Setting up new root fs

   setuproot: moving /dev failed: No such file or directory

   no fstab.sys, mounting internal defaults

   setuproot: error mounting /proc: No such file or directory

   setuproot: error mounting /sys: No such file or directory

   Switching to new root and running init.

   unmounting old /dev

   unmounting old /proc

   unmounting old /sys

   switchroot: mount failed: No such file or directory

   init used greatest stack depth: 4888 bytes left

   Kernel panic - not syncing: Attempted to kill init!

   Pid: 1, comm: init Not tainted 2.6.32.10 #2

   Call Trace:

   [<ffffffff8105b747>] panic+0xa5/0x167

   [<ffffffff8100ed81>] ? xen_force_evtchn_callback+0xd/0xf

   [<ffffffff81475d48>] ? _write_unlock_irq+0x30/0x3c

   [<ffffffff8108c9f4>] ? trace_hardirqs_on_caller+0x110/0x134

   [<ffffffff8108ca25>] ? trace_hardirqs_on+0xd/0xf

   [<ffffffff81475d4f>] ? _write_unlock_irq+0x37/0x3c

   [<ffffffff8105efa7>] do_exit+0x7e/0x701

   [<ffffffff8105f6c6>] sys_exit_group+0x0/0x1b

   [<ffffffff8105f6dd>] sys_exit_group+0x17/0x1b

   [<ffffffff81012d72>] system_call_fastpath+0x16/0x1b

   On Sat, Apr 17, 2010 at 5:22 AM, Pasi Kärkkäinen <[1]pasik@xxxxxx> wrote:

     On Fri, Apr 16, 2010 at 03:24:53PM -0700, kishore kumar wrote:
     >    I am using my Dom 0 kernel to boot as my Dom U.
     >    I edited /etc/xen/xmexample1 file and modified only below lines
     >
     >    kernel="/boot/vmlinux-2.6.32.10"
     >    memory=512
     >    vcpus=5
     >    root = "/dev/VolGroup01/LogVol00 ro"
     >    Below is the output I pasted after freezing.  Not sure what is
     wrong.  Can
     >    you please help me here??
     >    I doubt if I have provided the correct root option?
     >

     I bet that kernel has xen block frontend driver as a module?

     You don't seem to have ramdisk/initrd image,
     so you simply don't have the driver loaded at all
     to access the root disk in the guest.

     You must create an initrd image that loads the driver module in the
     guest.
     >
     >    VFS: Cannot open root device "VolGroup01/LogVol00" or
     unknown-block(0,0)
     >
     >    Please append a correct "root=" boot option; here are the available
     >    partitions:
     >
     >    Kernel panic - not syncing: VFS: Unable to mount root fs on
     >    unknown-block(0,0)
     >

     Root was not found - this is usually because you don't have the xen
     blockdev frontend driver loaded.
     -- Pasi

References

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Re: [Xen-devel] Xen Dom U kernel