Detecting xen

[Ed Brown]

> just check for the /proc/xen/capabilities file.

Sounds like the OP is looking to distinguish xen guests.  The file 
above is also present on hosts, or any system running a xen kernel I'd 
guess.  Can this file also be used to reliably distinguish between 
guests and non-guests?  On the few systems I've got to check against, 
  the capabilities file contains: "control_d" on hosts, while on all 
(pv) guests, the file is empty.

Also I don't know how reliable, this is, or will remain, but xen 
guests are the only systems I've got where 'lspci' returns nothing 
(successfully).

-Ed