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Commit 147ea091 authored by Dave Hansen's avatar Dave Hansen Committed by Ingo Molnar
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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: default avatarDave 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: default avatarIngo Molnar <mingo@kernel.org>
parent c391c788

Documentation/kernel-parameters.txt

+14 −2
Original line number Diff line number Diff line
@@ -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.

Documentation/x86/x86_64/boot-options.txt

+0 −14
Original line number Diff line number Diff line
@@ -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