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x86/doc: Fix Documentation/x86/earlyprintk.txt 

Fix a few issues in Documentation/x86/earlyprintk.txt:

- correct typos, punctuation, missing word, wrong word
- change product name from Netchip to NetChip
- expand where to add "earlyprintk=dbg"

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Link: http://lkml.kernel.org/r/d0c40ac3-7659-6374-dbda-23d3d2577f30@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Randy Dunlap 2018-08-05 20:34:05 -07:00 committed by Ingo Molnar
parent 11da3a7f84
commit 07e846bace
1 changed files with 15 additions and 10 deletions
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25
Documentation/x86/earlyprintk.txt
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@ -35,25 +35,25 @@ and two USB cables, connected like this:
( If your system does not list a debug port capability then you probably
won't be able to use the USB debug key. )
b.) You also need a Netchip USB debug cable/key:
b.) You also need a NetChip USB debug cable/key:
http://www.plxtech.com/products/NET2000/NET20DC/default.asp
This is a small blue plastic connector with two USB connections,
This is a small blue plastic connector with two USB connections;
it draws power from its USB connections.
c.) You need a second client/console system with a high speed USB 2.0
port.
d.) The Netchip device must be plugged directly into the physical
d.) The NetChip device must be plugged directly into the physical
debug port on the "host/target" system. You cannot use a USB hub in
between the physical debug port and the "host/target" system.
The EHCI debug controller is bound to a specific physical USB
port and the Netchip device will only work as an early printk
port and the NetChip device will only work as an early printk
device in this port. The EHCI host controllers are electrically
wired such that the EHCI debug controller is hooked up to the
first physical and there is no way to change this via software.
first physical port and there is no way to change this via software.
You can find the physical port through experimentation by trying
each physical port on the system and rebooting. Or you can try
and use lsusb or look at the kernel info messages emitted by the
@ -65,9 +65,9 @@ and two USB cables, connected like this:
to the hardware vendor, because there is no reason not to wire
this port into one of the physically accessible ports.
e.) It is also important to note, that many versions of the Netchip
e.) It is also important to note, that many versions of the NetChip
device require the "client/console" system to be plugged into the
right and side of the device (with the product logo facing up and
right hand side of the device (with the product logo facing up and
readable left to right). The reason being is that the 5 volt
power supply is taken from only one side of the device and it
must be the side that does not get rebooted.
@ -81,13 +81,18 @@ and two USB cables, connected like this:
CONFIG_EARLY_PRINTK_DBGP=y
And you need to add the boot command line: "earlyprintk=dbgp".
(If you are using Grub, append it to the 'kernel' line in
/etc/grub.conf)
/etc/grub.conf. If you are using Grub2 on a BIOS firmware system,
append it to the 'linux' line in /boot/grub2/grub.cfg. If you are
using Grub2 on an EFI firmware system, append it to the 'linux'
or 'linuxefi' line in /boot/grub2/grub.cfg or
/boot/efi/EFI/<distro>/grub.cfg.)
On systems with more than one EHCI debug controller you must
specify the correct EHCI debug controller number. The ordering
comes from the PCI bus enumeration of the EHCI controllers. The
default with no number argument is "0" the first EHCI debug
default with no number argument is "0" or the first EHCI debug
controller. To use the second EHCI debug controller, you would
use the command line: "earlyprintk=dbgp1"
@ -111,7 +116,7 @@ and two USB cables, connected like this:
see the raw output.
c.) On Nvidia Southbridge based systems: the kernel will try to probe
and find out which port has debug device connected.
and find out which port has a debug device connected.
3. Testing that it works fine: