Re: [Xen-users] Upgrade to 3.1 and backout plan

["Fajar A. Nugraha" <fajar@xxxxxxxxxxxxx>]

Gregory Gee wrote:
>
>  So I am planning on upgrading my dom0 from 3.0.4 to 3.1.0.  I have
> already done this for the domU's.  But I need to know my backout plan
> if something doesn't go right.  I have a simple question.
>
>  If I install the 3.1.0 from the tarball, can I still boot the 3.0.4
> dom0 kernel with the 3.1.0 Xen tools if needed?
No.
You can use kernels build for xen 3.0.3 on 3.1, but the xen userland
tools must match xen version.
>   I'm not sure of the compatibility.   I had to compile my own 3.0.4
> kernel because of missing SATA drivers in 2.6.16, but I believe they
> are in 2.6.18, which Xen 3.1.0 is based on.    I'll try and boot the
> 3.1.0 kernel, but if it fails, can I boot the 3.0.4 kernel even though
> the xm tools are 3.1.0?
>

What distro are you using?
On RHEL5 x86_64 :
- xen.gz is provided by kernel-xen RPM
- xen userland tools is provided by xen RPM, which in turn needs xen-libs

For a clean update to xen 3.1, you need to provide kernel-xen, xen, and
xen-libs RPM.
It also means you can't have kernel-xen updates from RH automatically
used by default (set UPDATEDEFAULT=no in /etc/sysconfig/kernel) since it
has xen.gz from xen 3.0.3.

Here's what I did :
- create my own xen-3.1.0-0.2.fan.x86_64.rpm, using RH's Xen-3.0.5 SRPM
as a starting point
- download RH's xen-3.0.3-25.0.3.el5.x86_64.rpm
xen-libs-3.0.3-25.0.3.el5.x86_64.rpm, for fallback purposes.
- yum erase xen-libs.i386
- rpm -Uvh xen-3.1.0-0.2.fan.x86_64.rpm xen-libs-3.1.0-0.2.fan.x86_64.rpm
- copy /usr/lib64/xen/xen.gz (created by my xen-3.1 rpm) to
/boot/xen.gz-3.1.0-src
- create an entry in /boot/grub/menu.lst that looks like this

title Xen 3.1 (2.6.18-8.1.10.el5xen)
        root (hd0,0)
        kernel /xen.gz-3.1.0-src console=vga
        module /vmlinuz-2.6.18-8.1.10.el5xen ro root=/dev/rootvg/rootlv
quiet xencons=tty
        module /initrd-2.6.18-8.1.10.el5xen.img

note that I just copy an existing kernel-xen section, and change the
"kernel" line.

- set UPDATEDEFAULT=no in /etc/sysconfig/kernel
- reboot

Fallback scenario :
- rpm -Uvh --oldpackage xen-3.0.3-25.0.3.el5.x86_64.rpm
xen-libs-3.0.3-25.0.3.el5.x86_64.rpm
- edit /boot/grub/menu.lst to use the original entry

Regards,

Fajar

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