x86, early-printk: Update earlyprintk documentation (and kill x86 copy)

Documentation/kernel-parameters.txt and
Documentation/x86/x86_64/boot-options.txt contain virtually
identical text describing earlyprintk.

This consolidates the two copies and updates the documentation a
bit.  No one ever documented the:

	earlyprintk=serial,0x1008,115200

syntax, nor mentioned that ARM is now a supported earlyprintk
arch.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rob Landley <rob@landley.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20130410210338.E2930E98@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4609e81dbc37fc2dbfa005ff607890df3a8bbc6b..b5cfd047becb9e26ce01dcc75c0e5912193a60ca 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -757,19 +757,31 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        (mmio) or 32-bit (mmio32).
                        The options are the same as for ttyS, above.
 
-       earlyprintk=    [X86,SH,BLACKFIN]
+       earlyprintk=    [X86,SH,BLACKFIN,ARM]
                        earlyprintk=vga
                        earlyprintk=xen
                        earlyprintk=serial[,ttySn[,baudrate]]
+                       earlyprintk=serial[,0x...[,baudrate]]
                        earlyprintk=ttySn[,baudrate]
                        earlyprintk=dbgp[debugController#]
 
+                       earlyprintk is useful when the kernel crashes before
+                       the normal console is initialized. It is not enabled by
+                       default because it has some cosmetic problems.
+
                        Append ",keep" to not disable it when the real console
                        takes over.
 
                        Only vga or serial or usb debug port at a time.
 
-                       Currently only ttyS0 and ttyS1 are supported.
+                       Currently only ttyS0 and ttyS1 may be specified by
+                       name.  Other I/O ports may be explicitly specified
+                       on some architectures (x86 and arm at least) by
+                       replacing ttySn with an I/O port address, like this:
+                               earlyprintk=serial,0x1008,115200
+                       You can find the port for a given device in
+                       /proc/tty/driver/serial:
+                               2: uart:ST16650V2 port:00001008 irq:18 ...
 
                        Interaction with the standard serial driver is not
                        very good.

diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index e015a83c3996262a50e444c3b843e599cc327e1d..e9e8ddbbf376253bd093db46d1695dccd9e06f1e 100644 (file)
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -91,20 +91,6 @@ APICs
                 apicmaintimer. Useful when your PIT timer is totally
                 broken.
 
-Early Console
-
-   syntax: earlyprintk=vga
-           earlyprintk=serial[,ttySn[,baudrate]]
-
-   The early console is useful when the kernel crashes before the
-   normal console is initialized. It is not enabled by
-   default because it has some cosmetic problems.
-   Append ,keep to not disable it when the real console takes over.
-   Only vga or serial at a time, not both.
-   Currently only ttyS0 and ttyS1 are supported.
-   Interaction with the standard serial driver is not very good.
-   The VGA output is eventually overwritten by the real console.
-
 Timing
 
   notsc