Re: [Xen-users] Xen domU cannot boot via PV-GRUB

[GNUbie <gnubie@xxxxxxxxx>]

Hello Fajar,

On Fri, Jan 14, 2011 at 3:47 PM, Fajar A. Nugraha <list@xxxxxxxxx> wrote:
>
> Let me make this reaaaaaaly simple. You were able to captrure boot
> log. That's good.
> Your previous boot log shows these
>
> [    0.071713] XENBUS: Device with no driver: device/vbd/2050
> [    0.071718] XENBUS: Device with no driver: device/vbd/2064
> [    0.071722] XENBUS: Device with no driver: device/vbd/2051
>
> whish should roughly mean you have three block devices on that domU.
> Do you know what they are? If not, you need to find out (whether from
> domU config file, some kind of Amazon EC2 config page, ask Amazon
> support, whatever).

Maybe that 3 block devices were from its original domU where
previously (from where this domU came from), it comes with the
following partitions:

/dev/xvda1 => /
/dev/xvda2 => /media/ephemeral0
/dev/xvda3 => SWAP

> You got the following block IDs (you can derive these from 256*major
> number + minor number):
> sda -> 2048
> sda2 -> 2050
> sda3 -> 2051
> sdb -> 2064
>
> so you do NOT have anything mapped as sda or xvda.
> You NEED to know how you currently have it mapped.
> You NEED to know what those three block devices that you currently have are.
> You NEED to map your current boot device to sda/xvda/hda/whatever
> (since you have partitions on it)

When you say "boot device", are you referring to the whole / or just
the /boot? As I mentioned on my previous message that the /dev/xvda1
or /dev/xvda contains the entire / filesystem including the /boot.

Below is the output of the "fdisk -l" command from a working (old) domU:

# fdisk -l

Disk /dev/xvda1: 10.5 GB, 10485761024 bytes
255 heads, 63 sectors/track, 1274 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/xvda1 doesn't contain a valid partition table

Disk /dev/xvda2: 160.1 GB, 160104972288 bytes
255 heads, 63 sectors/track, 19464 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/xvda2 doesn't contain a valid partition table

Disk /dev/xvda3: 939 MB, 939524096 bytes
255 heads, 63 sectors/track, 114 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/xvda3 doesn't contain a valid partition table

> Perhaps you forgot to build partition support (CONFIG_MSDOS_PARTITION=y)?

# grep -i dos config-2.6.34.7-56.40.i686
# DOS/FAT/NT Filesystems
CONFIG_MSDOS_FS=m
CONFIG_MSDOS_PARTITION=y

> In any case:
> - find out EXACTLY what your config is like
> - map disks the way you want it (e.g map first disk as xvda, NOT
> xvda1). Ask Amazon support if you don't know how.
> - make sure the necessary kernel support is builtin (partition
> support, xen frontend block driver, etc.). If you don't know about
> these things simply start with your distro's default kernel.

I'm using the Amazon Linux AMI 32bit distro which is based on
RedHat/CentOS and I am using the stock kernel of the said
distribution.

By the way, below is the init script inside my initrd image:

- - - < s n i p > - - -
#!/bin/nash

mount -t proc /proc /proc
setquiet
echo Mounting proc filesystem
echo Mounting sysfs filesystem
mount -t sysfs /sys /sys
echo Creating /dev
mount -o mode=0755 -t tmpfs /dev /dev
mkdir /dev/pts
mount -t devpts -o gid=5,mode=620 /dev/pts /dev/pts
mkdir /dev/shm
mkdir /dev/mapper
echo Creating initial device nodes
mknod /dev/null c 1 3
mknod /dev/zero c 1 5
mknod /dev/urandom c 1 9
mknod /dev/systty c 4 0
mknod /dev/tty c 5 0
mknod /dev/console c 5 1
mknod /dev/ptmx c 5 2
mknod /dev/rtc c 10 135
mknod /dev/tty0 c 4 0
mknod /dev/tty1 c 4 1
mknod /dev/tty2 c 4 2
mknod /dev/tty3 c 4 3
mknod /dev/tty4 c 4 4
mknod /dev/tty5 c 4 5
mknod /dev/tty6 c 4 6
mknod /dev/tty7 c 4 7
mknod /dev/tty8 c 4 8
mknod /dev/tty9 c 4 9
mknod /dev/tty10 c 4 10
mknod /dev/tty11 c 4 11
mknod /dev/tty12 c 4 12
mknod /dev/ttyS0 c 4 64
mknod /dev/ttyS1 c 4 65
mknod /dev/ttyS2 c 4 66
mknod /dev/ttyS3 c 4 67
echo Setting up hotplug.
hotplug
echo Creating block device nodes.
mkblkdevs
echo "Loading mbcache.ko module"
insmod /lib/mbcache.ko
echo "Loading jbd.ko module"
insmod /lib/jbd.ko
echo "Loading ext3.ko module"
insmod /lib/ext3.ko
echo "Loading xen-blkfront.ko module"
insmod /lib/xen-blkfront.ko
echo "Loading xen-blkfront.ko module"
insmod /lib/xen-blkfront.ko
echo "Loading dm-mod.ko module"
insmod /lib/dm-mod.ko
echo "Loading dm-log.ko module"
insmod /lib/dm-log.ko
echo "Loading dm-region-hash.ko module"
insmod /lib/dm-region-hash.ko
echo "Loading dm-mirror.ko module"
insmod /lib/dm-mirror.ko
echo "Loading dm-zero.ko module"
insmod /lib/dm-zero.ko
echo "Loading dm-snapshot.ko module"
insmod /lib/dm-snapshot.ko
echo "Loading dm-region-hash.ko module"
insmod /lib/dm-region-hash.ko
echo "Loading xen-blkfront.ko module"
insmod /lib/xen-blkfront.ko
echo "Loading xen-netfront.ko module"
insmod /lib/xen-netfront.ko
echo "Loading xen-netfront.ko module"
insmod /lib/xen-netfront.ko
mkblkdevs
echo Scanning and configuring dmraid supported devices
resume /dev/xvda3
echo Creating root device.
mkrootdev -t ext3 -o defaults,noatime,ro /dev/xvda1
echo Mounting root filesystem.
mount /sysroot
echo Setting up other filesystems.
setuproot
echo Switching to new root and running init.
switchroot
- - - < s n i p > - - -

Below is the list of the modules inside the initrd's lib directory:

# ls -l lib/
total 388
-rw------- 1 root root  11140 Jan 14 16:32 dm-log.ko
-rw------- 1 root root  16948 Jan 14 16:32 dm-mirror.ko
-rw------- 1 root root  69876 Jan 14 16:32 dm-mod.ko
-rw------- 1 root root  11280 Jan 14 16:32 dm-region-hash.ko
-rw------- 1 root root  35332 Jan 14 16:32 dm-snapshot.ko
-rw------- 1 root root   2796 Jan 14 16:32 dm-zero.ko
-rw------- 1 root root 129192 Jan 14 16:32 ext3.ko
drwx------ 2 root root   1024 Jan 14 16:32 firmware
-rw------- 1 root root  60528 Jan 14 16:32 jbd.ko
-rw------- 1 root root   8676 Jan 14 16:32 mbcache.ko
-rw------- 1 root root  16696 Jan 14 16:32 xen-blkfront.ko
-rw------- 1 root root  20348 Jan 14 16:32 xen-netfront.ko

Does it mean that I have to rebuild the initrd and change/correct all
the xvd* existence to sd*?

Thank you.

Regards,

GNUbie

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