doc, xen: Mention 'earlyprintk=xen' in the documentation.
The earlyprintk for Xen PV guests utilizes a simple hypercall
(console_io) to provide output to Xen emergency console.
Note that the Xen hypervisor should be booted with 'loglevel=all'
to output said information.
Reported-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/1361825650-14031-2-git-send-email-konrad.wilk@oracle.com
Cc: <stable@vger.kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6c72381..c4cc199 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -754,6 +754,7 @@
earlyprintk= [X86,SH,BLACKFIN]
earlyprintk=vga
+ earlyprintk=xen
earlyprintk=serial[,ttySn[,baudrate]]
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
@@ -771,6 +772,8 @@
The VGA output is eventually overwritten by the real
console.
+ The xen output can only be used by Xen PV guests.
+
ekgdboc= [X86,KGDB] Allow early kernel console debugging
ekgdboc=kbd