header functions for osv + xen

Should come from OSv, we should fix this soon.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>

core/xen/osv_xen.hh

@@ -0,0 +1,30 @@
+#ifndef _XEN_HH
+#define _XEN_HH
+// Those should come directly from the OSv three. However, the xen exported
+// functions are not currently living in osv/include, but spread around the
+// BSD directory. We should move them there ASAP and then use them here.
+extern int
+bind_listening_port_to_irq(unsigned int remote_domain, int * port);
+extern int
+evtchn_from_irq(int irq);
+extern int
+notify_remote_via_evtchn(int port);
+extern void
+unmask_evtchn(int port);
+extern "C" int
+intr_add_handler(const char *name, int vector, void *filter,
+                 void (*handler)(void *arg), void *arg, int flags,
+                 void **cookiep);
+
+extern int
+gnttab_alloc_grant_references(uint16_t count, uint32_t *head);
+extern int
+gnttab_claim_grant_reference(uint32_t *private_head);
+
+extern int
+gnttab_grant_foreign_access(uint16_t domid, unsigned long frame, int readonly, uint32_t *result);
+extern void gnttab_grant_foreign_access_ref(uint32_t ref, uint16_t domid, unsigned long frame, int readonly);
+
+extern "C" uint64_t
+virt_to_phys(void *virt);
+#endif