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 <[email protected]>
---
linux.git-davehans/Documentation/kernel-parameters.txt | 16 +++++++++--
linux.git-davehans/Documentation/x86/x86_64/boot-options.txt | 14 ---------
2 files changed, 14 insertions(+), 16 deletions(-)
diff -puN Documentation/kernel-parameters.txt~early-printk-morettys
Documentation/kernel-parameters.txt
--- linux.git/Documentation/kernel-parameters.txt~early-printk-morettys
2013-04-10 13:30:37.422949520 -0700
+++ linux.git-davehans/Documentation/kernel-parameters.txt 2013-04-10
13:30:37.428949526 -0700
@@ -757,19 +757,31 @@ bytes respectively. Such letter suffixes
(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 -puN Documentation/x86/x86_64/boot-options.txt~early-printk-morettys
Documentation/x86/x86_64/boot-options.txt
--- linux.git/Documentation/x86/x86_64/boot-options.txt~early-printk-morettys
2013-04-10 13:30:37.424949522 -0700
+++ linux.git-davehans/Documentation/x86/x86_64/boot-options.txt
2013-04-10 13:30:37.428949526 -0700
@@ -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
_
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