Xen users - Dec 2011 - xm vcpu-set problem & question

Hello,
I have run new node with AMD 1090T.

When trying to set:
xm vcpu-set 0 1
server hangs up and reboot.

I have read info about cpu hotplug bug. But I am using same kernel on
few other nodes (intel & amd cpus) without any problems.

So I set in grub:
dom0_max_vcpus=1 dom0_vcpus_pin

But problem is that xen shows only one vcpu:

[root@node26 ~]# xm vcpu-list
Name                                ID  VCPU   CPU State   Time(s) CPU
Affinity
Domain-0                             0     0     0   r--      48.7 0

It`s strange for me because on other nodes I have something like:

[root@node22 ~]# xm vcpu-list
Name                                ID  VCPU   CPU State   Time(s) CPU
Affinity
Domain-0                             0     0     0   r--   82528.6 0
Domain-0                             0     1     -   --p       3.0 any cpu
Domain-0                             0     2     -   --p       2.9 any cpu
Domain-0                             0     3     -   --p       2.7 any cpu

So - is it ok that xen shows only one vcpu?
xm info says:
nr_cpus                : 6
nr_nodes               : 1
cores_per_socket       : 6

so theoreticly its ok - but I am not sure, thats why I am asking you.

Thanks in advance.