Re: Xen Dom U kernel

[listmail <listmail@triad.rr.com>]

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 the 
dom0 to the domU.  Is this more of an issue when LVM is implemented on 
the domU itself???  That's what I am seeing here.  Should he be adding a 
break=premount option to initrd and checking visibility of the LVM root 
from 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@iki.fi> 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
>>
>>    Visible links
>>    1. mailto:pasik@iki.fi
>>     
>
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