xen: add and enable Xen console for PVH guests

This adds and enables the PV console used on XEN kernels to
GENERIC/XENHVM kernels in order for it to be used on PVH.

Approved by: gibbs
Sponsored by: Citrix Systems R&D

dev/xen/console/console.c:
 - Define console_page.
 - Move xc_printf debug function from i386 XEN code to generic console
   code.
 - Rework xc_printf.
 - Use xen_initial_domain instead of open-coded checks for Dom0.
 - Gate the attach of the PV console to PV(H) guests.

dev/xen/console/xencons_ring.c:
 - Allow the PV Xen console to output earlier by directly signaling
   the event channel in start_info if the event channel is not yet
   initialized.
 - Use HYPERVISOR_start_info instead of xen_start_info.

i386/include/xen/xen-os.h:
 - Remove prototype for xc_printf since it's now declared in global
   xen-os.h

i386/xen/xen_machdep.c:
 - Remove previous version of xc_printf.
 - Remove definition of console_page (now it's defined in the console
   itself).
 - Fix some printf formatting errors.

x86/xen/pv.c:
 - Add some early boot debug messages using xc_printf.
 - Set console_page based on the value passed in start_info.

xen/xen-os.h:
 - Declare console_page and add prototype for xc_printf.

1 files changed, 0 insertions, 1 deletions

diff --git a/sys/i386/include/xen/xen-os.h b/sys/i386/include/xen/xen-os.h
index a8fba61..3d1ef04 100644
--- a/sys/i386/include/xen/xen-os.h
+++ b/sys/i386/include/xen/xen-os.h
@@ -45,7 +45,6 @@ static inline void rep_nop(void)
 #define cpu_relax() rep_nop()
 
 #ifndef XENHVM
-void xc_printf(const char *fmt, ...);
 
 #ifdef SMP
 extern int gdtset;