[Libguestfs] Extlinux with guestfish

[Richard W.M. Jones]

On Tue, Oct 20, 2015 at 06:15:05PM +0100, slim tabka wrote:
> Thank you for the quick response.
> 
> > Strange way to do this, as libguestfs can do all this.
> 
> Sorry to ask this (I'm a newly graduated engineer and I new to the
> virtualization world), but how can libguestfs do all of the above?, do you
> mean it can create all the partitions inside a new lvm volume or a new raw
> image??

Of course:

# guestfish -a /dev/vg/lv_test
><fs> run
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ --:--
><fs> part-init /dev/sda msdos
><fs> part-disk /dev/sda msdos
><fs> mkfs ext4 /dev/sda1
><fs> mount /dev/sda1 /
><fs> tgz-in /tmp/libguestfs-1.31.18.tar.gz /
etc.

but replace /tmp/libguestfs-1.31.18.tar.gz with your CentOS tarball.

> > Did you copy the syslinux.cfg file into the guest?  The error message
> > you reported sounds like extlinux is installed but cannot read its
> > config file.
> 
> Yes I'm sure that I copied the syslinux.cfg in the guest and that's why I
> was confused with the error message.
>
> My problem is that the exact same steps  worked on a ubuntu 14.04  host
> with libguestfs 1.24.5 , and I can't see why it won't work on a centos7
> host , that's why I thought about a problem with this libguestfs version
> (1.30.3).
>
> Here's how I installed extlinux (I already saw the link that you sent me
> and I don't think I made a mistake) but the guest still don't want to boot:
> 
> [root at localhost libguestfs-1.30.3]# ./run guestfish -i -a
> /dev/vm_volumes/clone2
> 
> Welcome to guestfish, the guest filesystem shell for
> editing virtual machine filesystems and disk images.
> 
> Type: 'help' for help on commands
>       'man' to read the manual
>       'quit' to quit the shell
> 
> Operating system: CentOS Linux release 7.1.1503 (Core)
> /dev/sda1 mounted on /
> 
> ><fs> ls /boot/
> .vmlinuz-3.10.0-229.el7.x86_64.hmac
> System.map-3.10.0-229.el7.x86_64
> config-3.10.0-229.el7.x86_64
> grub
> grub2
> initramfs-0-rescue-c898899928d341b58ae4d02802d19340.img
> initramfs-3.10.0-229.el7.x86_64.img
> initramfs-3.10.0-229.el7.x86_64kdump.img
> initrd-plymouth.img
> ldlinux.sys
> mbr.bin
> symvers-3.10.0-229.el7.x86_64.gz
> syslinux.cfg
> vmlinuz-0-rescue-c898899928d341b58ae4d02802d19340
> vmlinuz-3.10.0-229.el7.x86_64
> ><fs> cat /boot/syslinux.cfg
> DEFAULT linux
>         LABEL linux
>           SAY Booting the kernel
>           KERNEL /boot/vmlinuz-3.10.0-229.el7.x86_64
>           INITRD /boot/initramfs-3.10.0-229.el7.x86_64.img
>           APPEND ro root=UUID=8e137cd9-cd6c-4205-a27f-211d6184a5f3
> 
> ><fs> copy-file-to-device /boot/mbr.bin /dev/sda size:440
> ><fs> extlinux /boot
> ><fs> part-set-bootable /dev/sda 1 true

I wonder if extlinux is confused because /boot isn't a separate
partition?

TBH this is most likely an extlinux problem, since all that libguestfs
does is to run `extlinux --install /boot', and if that command isn't
working it's probably not because of anything libguestfs does.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org