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>
This commit is contained in:
Konrad Rzeszutek Wilk 2013-02-25 15:54:08 -05:00 committed by H. Peter Anvin
parent 565d956a7e
commit 2482a92e7d
1 changed files with 3 additions and 0 deletions

View File

@ -754,6 +754,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
earlyprintk= [X86,SH,BLACKFIN]
earlyprintk=vga
earlyprintk=xen
earlyprintk=serial[,ttySn[,baudrate]]
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
@ -771,6 +772,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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