Re: [Xen-users] Problem in updating linux kernel in a remote xen virtual machine

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

Xen has two common ways of loading a kernel for a PV guest.

One way is the use of "pygrub" which reads the guest's menu.lst and boots the 
kernel that specifies.  The other is by loading a kernel *outside* the 
guest's filesystem: i.e. the kernel is in dom0 and you can't change it.

If your guest is setup for the latter then there's nothing straightforward you 
can do to make the guest boot into your new kernel.

Which of these approaches is used is determined by the guest config file, 
which is in /etc/xen in dom0.  Do you have access to the dom0, in which case 
this should be easy to check?  If not, maybe you can ask your dom0 
administrator (e.g. your hosting provider) about updating your kernel or 
switching over to pygrub.

Cheers,
Mark

> > > The currently working kernel in that xen VM is linux-2.6.16.46-0.12,
> > > the local version is "-xen".
> > >
> > > I added one module, several kernel hacking options, and change the
> > > local version to "-mine". After recompiling, I set this "-mine" kernel
> > > as my default one in /boot/grub/menu.lst.
> > >
> > > But the remote xen VM always boots with the original "-xen" kernel,
> > > ignoring the "default" setting in the menu.lst. (I have not yet the
> > > graphic access to the VM and host). Also I can not "modprobe" the
> > > module I added.
> > >
> > > So, I don't know what's wrong. Is there any difference in updating
> > > kernels in VM? Or is there any general setting to set which kernels a
> > > VM can boot with?
> > >
> > > Thank you so much.
> > >
> > > BTW, when doing kernel recompiling, I did
> > >
> > > #make menuconfig
> > > #make clean
> > > #make
> > > #make modules_install install
> > >
> > > At this point,
> > > System.map-2.6.16.46-0.12-mine
> > > config-2.6.16.46-0.12-mine
> > > vmlinux-syms-2.6.16.46-0.12-mine
> > > vmlinuz-2.6.16.46-0.12-mine
> > >
> > > were generated and copied to /boot automatically, but no
> > > initrd-2.6.16.46-0.12-mine. I had to use "mkinitrd" to generate
> > > it.Also, the "-mine" entry in the menu.lst need to be added manually.
> >
> > It might be true that you are not loading the guest kernel from domu
> > filesystem via pygrub. You may be passing the guest kernels from dom0 by
> > specifying kernel = and ramdisk = parameter in the guest configuration
> > file. If that is the case recompiling the kernel inside the guest
> > wouldn't take effect.
>
> You are right. I didn't do anything other than I mentioned.
>
> > How does your guest configuration file look like?
>
> Is this configuration file should be inside the guest machine? I looked
> for /etc directory, but didn't find /etc/xen sub-directory. What's its
> name? Should I look for it in other dirctories?
>
> Or, I should check the folders in the host?
>
> Thank you!
>
> > --Sadique
> >
> > > Thank you again.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Xen-users mailing list
> > > Xen-users@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xen-users
>
> _______________________________________________
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> http://lists.xensource.com/xen-users



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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