[Fedora-xen] Xen only showing 16GB of ram out of 28GB

[Gerd Hoffmann]

thewird wrote:
> I installed FC6 and FC7 and the limit exists on both even though FC7
> was supposed to be using a 64bit hypervisor which supports 32bit guests
> (which isn't the case).

WorksForMe[tm].  Test box with a bunch of systems installed, among them
fedora7 32bit and fedora7 64bit.  Booting the 32bit fedora dom0 with the
64bit hypervisor (aka /boot/xen.gz-<version>) from the 64bit
installation works just fine.

If you got it right "xm dmesg" looks like this:
[ ... ]
(XEN)  Xen  kernel: 64-bit, lsb, compat32
(XEN)  Dom0 kernel: 32-bit, PAE, lsb, paddr 0xc1000000 -> 0xc15e2000
[ ... ]

The limitation is that the dom0 kernel backend drivers don't support
32-on-64, so you can't mix 32bit and 64bit domains.  As long as dom0 and
all guests are identical it works.

cheers,
  Gerd