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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: 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>
Dave Hansen 12 年之前
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147ea09119
共有 2 个文件被更改,包括 14 次插入16 次删除
  1. 14 2
      Documentation/kernel-parameters.txt
  2. 0 14
      Documentation/x86/x86_64/boot-options.txt

+ 14 - 2
Documentation/kernel-parameters.txt

@@ -757,19 +757,31 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			(mmio) or 32-bit (mmio32).
 			(mmio) or 32-bit (mmio32).
 			The options are the same as for ttyS, above.
 			The options are the same as for ttyS, above.
 
 
-	earlyprintk=	[X86,SH,BLACKFIN]
+	earlyprintk=	[X86,SH,BLACKFIN,ARM]
 			earlyprintk=vga
 			earlyprintk=vga
 			earlyprintk=xen
 			earlyprintk=xen
 			earlyprintk=serial[,ttySn[,baudrate]]
 			earlyprintk=serial[,ttySn[,baudrate]]
+			earlyprintk=serial[,0x...[,baudrate]]
 			earlyprintk=ttySn[,baudrate]
 			earlyprintk=ttySn[,baudrate]
 			earlyprintk=dbgp[debugController#]
 			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
 			Append ",keep" to not disable it when the real console
 			takes over.
 			takes over.
 
 
 			Only vga or serial or usb debug port at a time.
 			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
 			Interaction with the standard serial driver is not
 			very good.
 			very good.

+ 0 - 14
Documentation/x86/x86_64/boot-options.txt

@@ -91,20 +91,6 @@ APICs
 		 apicmaintimer. Useful when your PIT timer is totally
 		 apicmaintimer. Useful when your PIT timer is totally
 		 broken.
 		 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
 Timing
 
 
   notsc
   notsc