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| author |   Lu Baolu <baolu.lu@linux.intel.com> | 2017-03-21 16:01:31 +0800 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2017-03-21 12:30:16 +0100 |
| commit | 1b5aeebf3a92273b4d85aeff37a16037bc3c3abf (patch) | |
| tree | 5e53cbb34ebef264bceb394985b2ad0b6a60e52f /Documentation/admin-guide | |
| parent | usb/early: Add driver for xhci debug capability (diff) | |
| download | linux-dev-1b5aeebf3a92273b4d85aeff37a16037bc3c3abf.tar.xz linux-dev-1b5aeebf3a92273b4d85aeff37a16037bc3c3abf.zip | |
x86/earlyprintk: Add support for earlyprintk via USB3 debug port
Add support for earlyprintk by writing debug messages to the
USB3 debug port. Users can use this type of early printk by
specifying the kernel parameter of "earlyprintk=xdbc". This
gives users a chance of providing debugging output.
The hardware for USB3 debug port requires DMA memory blocks.
This requires to delay setting up debugging hardware and
registering boot console until the memblocks are filled.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-usb@vger.kernel.org
Link: http://lkml.kernel.org/r/1490083293-3792-4-git-send-email-baolu.lu@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2ba45caabada..ea1293d60f17 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -989,6 +989,7 @@ earlyprintk=ttySn[,baudrate] earlyprintk=dbgp[debugController#] earlyprintk=pciserial,bus:device.function[,baudrate] + earlyprintk=xdbc[xhciController#] earlyprintk is useful when the kernel crashes before the normal console is initialized. It is not enabled by |