which bootloader to use? PVgrup, Py-grup,or host's kernel?

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#1 Wed, 09/01/2010 - 07:27
SoftDux

which bootloader to use? PVgrup, Py-grup,or host's kernel?

Hi all,

Which boot option is best for Linux based domU?

And what's the difference between the 3?

Mon, 09/13/2010 - 13:40
SoftDux

doesn't anyone know?

Mon, 09/13/2010 - 14:57 (Reply to #2)
JamieCameron

So the options and their differences are :

  1. Host kernel - the virtual system uses the same kernel as the host system
  2. PyGrub - the system uses the kernel from its own filesystem, specified in its grub config just like a real system
  3. PvGrub - the virtual system's kernel is also used. PvGrub is a newer bootloader than PyGrub and is considered more secure, but isn't available with some older Xen versions

Personally I recommend using PyGrub, as it lets each virtual system have a different kernel, and manage that kernel from within the VM just like on a real machine.

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Mon, 09/13/2010 - 17:51
ronald
ronald's picture

I agree. I switched to pygrub as using the hostkernel is a bit misleading.
It will use the hosts kernel version at initial install, but when the host's kernel gets updated, the guests do not.

Also it will now let me use 32bit guest systems on the 64bits host, which wouldn't let me properly before.

Tue, 09/14/2010 - 02:55
SoftDux

Thanx Jamie.

So, is there any benefit in using pvgrub then? Apart from the fact that it's more secure? In what sense though, is it more secure?

Tue, 09/14/2010 - 03:10 (Reply to #5)
JamieCameron

Apparently PvGrub is more secure because it runs grub within the VM, while PyGrub runs it on the host system - so theoretically a bug that allows an intentionally corrupted grub.conf file could be used by a VM owner to take control of the host system. As far as I know no such bug exists anymore, but even so ..

For more details, see http://wiki.xensource.com/xenwiki/PvGrub and http://wiki.xensource.com/xenwiki/PyGrub . Also see http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1068 for an example of the kind of bug I am talking about, although this one is fixed.

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