profiler can't init working with Xen on oneiric

[James Zhang]

My machines are dell optiplex 790 and dell latitude d620. Both of them are installed with Ubuntu 11.10. Xen 4.1.1 and Oprofile 0.9.6 are ubuntu version installed by synaptic. On d620, Oprofile works well after setting xen-syms. But, on optiplex 790, Oprofile works when only the linux kernel was booted. When I booted into xen, oprofile didn't generate samples and opcontrol --deinit leaded to error, so the Oprofile module can't be unloaded.