aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation
diff options
context:
space:
mode:
authorDave Hansen <dave@sr71.net>2013-04-10 14:03:38 -0700
committerIngo Molnar <mingo@kernel.org>2013-04-11 10:30:40 +0200
commit147ea09119e45caf2e8bf57c9e54cc930ccfeda9 (patch)
tree5b7c02dc0cf0ea2feea5887a2bf72337d4ba029f /Documentation
parentc391c7884633cdc317a60fbf152d1764282fe633 (diff)
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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kernel-parameters.txt16
-rw-r--r--Documentation/x86/x86_64/boot-options.txt14
2 files changed, 14 insertions, 16 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4609e81dbc37..b5cfd047becb 100644
--- 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 e015a83c3996..e9e8ddbbf376 100644
--- 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

Privacy Policy