Xen custom %p format options.  A subset, borrowed from Linux.

All parameters to a %p option should be compatible with void*.  Regular
pointers are fine.  Numbers should make use of the _p() macro.

Raw buffer as hex string:

       %*ph    Up to 64 characters, printed as "00 01 02 ... ff".  Buffer length
               expected via the field_width paramter. i.e. printk("%*ph", 8, buffer);

Symbol/Function pointers:

       %ps     Symbol name with condition offset and size (iff offset != 0)
                 e.g.  printk
                       default_idle+0x78/0x7d

       %pS     Symbol name with unconditional offset and size
                 e.g.  printk+0/0x48
                       default_idle+0x78/0x7d

       In the case that an appropriate symbol name can't be found, %p[sS] will
       fall back to '%p' and print the address in hex.

Domain and vCPU information:

       %pv     Domain and vCPU ID from a 'struct vcpu *' (printed as
               "d<domid>v<vcpuid>")
