diff options
| author | Dave Hansen <dave@sr71.net> | 2013-04-10 14:03:38 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-04-11 10:30:40 +0200 |
| commit | 147ea09119e45caf2e8bf57c9e54cc930ccfeda9 (patch) | |
| tree | 5b7c02dc0cf0ea2feea5887a2bf72337d4ba029f | |
| parent | c391c7884633cdc317a60fbf152d1764282fe633 (diff) | |
| download | lwn-147ea09119e45caf2e8bf57c9e54cc930ccfeda9.tar.gz lwn-147ea09119e45caf2e8bf57c9e54cc930ccfeda9.zip | |
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>
| -rw-r--r-- | Documentation/kernel-parameters.txt | 16 | ||||
| -rw-r--r-- | Documentation/x86/x86_64/boot-options.txt | 14 |
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 |