[Pkg-xen-devel] Bug#600241: Xen Hypervisor can only boot if "acpi=off" parameter is used.

[Daniel Requena]

Package: xen-hypervisor-4.0-amd64
Version: 4.0.1-1

Hardware specs:

Dell PowerEdge R410
32GB RAM DDR3
1TB RAID-1 HD (Perc H200 RAID controller)
Processor: 2 - Intel XeonE5620 2.4Ghz 12M Cache Turbo HT 1066MHz

SO: Debian Squeeze
last update: 14/10/2010
uname -a: "Linux spo-r1-u4 2.6.32-5-xen-amd64 #1 SMP Fri Sep 17 22:00:48 
UTC 2010 x86_64 GNU/Linux"

At boot, xen-hypervisor is loaded normally, but when it tries to load 
linux kernel it freezes. There is no screen output and after a few 
seconds, the server reboots.
However, the problem doesn't happen if "acpi=off" parameter is used on 
grub xen-hypervisor entry OR if the virtualization flags are disabled on 
the BIOS.
Using the "acpi=off" parameters Xen is not able to detect the 16 cores 
(8 fisical with hyperthread), only 8 cores. If the virtualization flags 
are disabled all the 16 cores are detect.

Xen grub entry:

menuentry 'Debian GNU/Linux, with Linux 2.6.32-5-xen-amd64 and XEN 
4.0-amd64' --class debian --class gnu-linux --class gnu --class os 
--class xen {
    insmod part_msdos
    insmod ext2
    set root='(hd0,msdos2)'
    search --no-floppy --fs-uuid --set 935213fd-c3c6-49ad-b818-a3b67704c585
    echo    'Loading Linux 2.6.32-5-xen-amd64 ...'
    multiboot    /xen-4.0-amd64.gz placeholder acpi=off  
    module    /vmlinuz-2.6.32-5-xen-amd64 placeholder 
root=/dev/mapper/main-root ro  quiet
    echo    'Loading initial ramdisk ...'
    module    /initrd.img-2.6.32-5-xen-amd64
}