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Gmane
From: Jason Wessel <jason.wessel <at> windriver.com>
Subject: [PATCH 0/7] early debugging kgdb & kdb proposed merge for 2.6.34
Newsgroups: gmane.linux.kernel
Date: Friday 12th February 2010 22:39:21 UTC (over 6 years ago)
Patch set 3 of 3 - The kdb / kgdb merge

This patch set stacks on top of the kgdb / kdb / kms patches and
focuses on allowing the kernel debugger to as early as the earlyprintk
is available.  Right now early debugging is only available on x86, but
the API in the debug core are generic and the only thing lacking for
other architecture support is appropriate atomic safe polled I/O
drivers.

The first few patches address the problems in kdb and the architecture
specific x86 kgdb implementation which rely on services which are not
available before the kernel memory allocators are setup.

The patch set includes the support for the vga and dbgp devices.  For
the vga case, it only works with kdb.  You could boot your kernel and
optionally include kgdbwait as follows:

     earlyprintk=vga ekgboc=kbd kgdbwait

That will stop the kernel somewhere inside setup_arch() and you can
plant breakpoints, modify memory and backtrace.  If you omit the
kgdbwait, the kgdb shell prompt will appear on the vga console only if
there is a kernel fault.

The final 2 patches in the series add support for the EHCI usb debug
port when using a dbgp device.  You have the choice of using
earlyprintk= or using only the kernel debugger on the debug port.  You
can also use either kgdb or kdb with this connection.  Here are two
example kernel boot argument lines:

1) Used in conjunction with earlyprintk on usb debug port 1

   	earlyprintk=dbgp1,keep kgdbdbgp=1 kgdbwait

2) Allow for the capability to break into the kernel with control-c on
   usb debug port 0

        kgdbdbp=0,1 kgdbwait

A patch to add formal documentation to the kgdb docbook for these new
features will be available for the 2.6.34 cycle, because there are a
number of other ways you can make use of these features not described
here.

You can find the development branch for this here:

http://git.kernel.org/?p=linux/kernel/git/jwessel/linux-2.6-kgdb.git;a=shortlog;h=dbg-early-merge

Thanks,
Jason.

---
Jan Kiszka (1):
      x86, kgdb: early trap init for early debug

Jason Wessel (7):
      x86, kgdb, init: Add early and late debug states
      x86,kgdb: Implement early hardware breakpoint debugging
      x86,early dr regs,kgdb: Allow kernel debugger early dr register
access
      kgdboc: Add ekgdboc for early use of the kernel debugger
      earlyprintk,vga,kdb: Fix \b and \r for earlyprintk=vga with kdb
      ehci-dbgp: split PID register updates for IN and OUT pipes
      echi-dbgp: Add kernel debugger support for the usb debug port

 Documentation/kernel-parameters.txt |   17 +++
 arch/x86/include/asm/processor.h    |    2 +
 arch/x86/kernel/cpu/common.c        |   29 +++---
 arch/x86/kernel/early_printk.c      |    8 ++
 arch/x86/kernel/kgdb.c              |   47 +++++++--
 arch/x86/kernel/setup.c             |    1 +
 arch/x86/kernel/traps.c             |   14 ++-
 drivers/serial/kgdboc.c             |   19 ++++
 drivers/usb/early/ehci-dbgp.c       |  184
++++++++++++++++++++++++++---------
 include/linux/kgdb.h                |   14 +++
 init/main.c                         |    4 +-
 kernel/debug/debug_core.c           |   16 +++
 12 files changed, 281 insertions(+), 74 deletions(-)

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