A.11 Debugging Hypercalls

A few additional hypercalls are mainly useful for debugging:

console_io(int cmd, int count, char *str)

Use Xen to interact with the console; operations are:

CONSOLEIO_write: Output count characters from buffer str.

CONSOLEIO_read: Input at most count characters into buffer str.

A pair of hypercalls allows access to the underlying debug registers:

set_debugreg(int reg, unsigned long value)

Set debug register reg to value

get_debugreg(int reg)

Return the contents of the debug register reg

And finally:

xen_version(int cmd)

Request Xen version number.

This is useful to ensure that user-space tools are in sync with the underlying hypervisor.