From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932504AbcHJSDe (ORCPT ); Wed, 10 Aug 2016 14:03:34 -0400 Received: from thoth.sbs.de ([192.35.17.2]:50516 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932458AbcHJSDW (ORCPT ); Wed, 10 Aug 2016 14:03:22 -0400 Subject: Re: [PATCH 10/10] docs: Sphinxify gdb-kernel-debugging.txt and move to dev-tools To: Jonathan Corbet , linux-doc@vger.kernel.org References: <20160808233502.16950-1-corbet@lwn.net> <20160808233502.16950-11-corbet@lwn.net> Cc: linux-kernel@vger.kernel.org, Jani Nikula From: Jan Kiszka Message-ID: Date: Wed, 10 Aug 2016 09:03:22 +0200 User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 In-Reply-To: <20160808233502.16950-11-corbet@lwn.net> Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016-08-09 01:35, Jonathan Corbet wrote: > Cc: Jan Kiszka > Signed-off-by: Jonathan Corbet > --- > .../gdb-kernel-debugging.rst} | 77 +++++++++++++--------- > Documentation/dev-tools/tools.rst | 1 + > 2 files changed, 46 insertions(+), 32 deletions(-) > rename Documentation/{gdb-kernel-debugging.txt => dev-tools/gdb-kernel-debugging.rst} (73%) > > diff --git a/Documentation/gdb-kernel-debugging.txt b/Documentation/dev-tools/gdb-kernel-debugging.rst > similarity index 73% > rename from Documentation/gdb-kernel-debugging.txt > rename to Documentation/dev-tools/gdb-kernel-debugging.rst > index 7050ce8..5e93c9b 100644 > --- a/Documentation/gdb-kernel-debugging.txt > +++ b/Documentation/dev-tools/gdb-kernel-debugging.rst > @@ -1,3 +1,5 @@ > +.. highlight:: none > + > Debugging kernel and modules via gdb > ==================================== > > @@ -13,54 +15,58 @@ be transferred to the other gdb stubs as well. > Requirements > ------------ > > - o gdb 7.2+ (recommended: 7.4+) with python support enabled (typically true > - for distributions) > +- gdb 7.2+ (recommended: 7.4+) with python support enabled (typically true > + for distributions) > > > Setup > ----- > > - o Create a virtual Linux machine for QEMU/KVM (see www.linux-kvm.org and > - www.qemu.org for more details). For cross-development, > - http://landley.net/aboriginal/bin keeps a pool of machine images and > - toolchains that can be helpful to start from. > +- Create a virtual Linux machine for QEMU/KVM (see www.linux-kvm.org and > + www.qemu.org for more details). For cross-development, > + http://landley.net/aboriginal/bin keeps a pool of machine images and > + toolchains that can be helpful to start from. > > - o Build the kernel with CONFIG_GDB_SCRIPTS enabled, but leave > - CONFIG_DEBUG_INFO_REDUCED off. If your architecture supports > - CONFIG_FRAME_POINTER, keep it enabled. > +- Build the kernel with CONFIG_GDB_SCRIPTS enabled, but leave > + CONFIG_DEBUG_INFO_REDUCED off. If your architecture supports > + CONFIG_FRAME_POINTER, keep it enabled. > > - o Install that kernel on the guest. > +- Install that kernel on the guest. > + Alternatively, QEMU allows to boot the kernel directly using -kernel, > + -append, -initrd command line switches. This is generally only useful if > + you do not depend on modules. See QEMU documentation for more details on > + this mode. > > - Alternatively, QEMU allows to boot the kernel directly using -kernel, > - -append, -initrd command line switches. This is generally only useful if > - you do not depend on modules. See QEMU documentation for more details on > - this mode. > +- Enable the gdb stub of QEMU/KVM, either > > - o Enable the gdb stub of QEMU/KVM, either > - at VM startup time by appending "-s" to the QEMU command line > - or > + > + or > + > - during runtime by issuing "gdbserver" from the QEMU monitor > console > > - o cd /path/to/linux-build > +- cd /path/to/linux-build > > - o Start gdb: gdb vmlinux > +- Start gdb: gdb vmlinux > > - Note: Some distros may restrict auto-loading of gdb scripts to known safe > - directories. In case gdb reports to refuse loading vmlinux-gdb.py, add > + Note: Some distros may restrict auto-loading of gdb scripts to known safe > + directories. In case gdb reports to refuse loading vmlinux-gdb.py, add:: > > add-auto-load-safe-path /path/to/linux-build > > - to ~/.gdbinit. See gdb help for more details. > + to ~/.gdbinit. See gdb help for more details. > + > +- Attach to the booted guest:: > > - o Attach to the booted guest: > (gdb) target remote :1234 > > > Examples of using the Linux-provided gdb helpers > ------------------------------------------------ > > - o Load module (and main kernel) symbols: > +- Load module (and main kernel) symbols:: > + > (gdb) lx-symbols > loading vmlinux > scanning for modules in /home/user/linux/build > @@ -72,17 +78,20 @@ Examples of using the Linux-provided gdb helpers > ... > loading @0xffffffffa0000000: /home/user/linux/build/drivers/ata/ata_generic.ko > > - o Set a breakpoint on some not yet loaded module function, e.g.: > +- Set a breakpoint on some not yet loaded module function, e.g.:: > + > (gdb) b btrfs_init_sysfs > Function "btrfs_init_sysfs" not defined. > Make breakpoint pending on future shared library load? (y or [n]) y > Breakpoint 1 (btrfs_init_sysfs) pending. > > - o Continue the target > +- Continue the target:: > + > (gdb) c > > - o Load the module on the target and watch the symbols being loaded as well as > - the breakpoint hit: > +- Load the module on the target and watch the symbols being loaded as well as > + the breakpoint hit:: > + > loading @0xffffffffa0034000: /home/user/linux/build/lib/libcrc32c.ko > loading @0xffffffffa0050000: /home/user/linux/build/lib/lzo/lzo_compress.ko > loading @0xffffffffa006e000: /home/user/linux/build/lib/zlib_deflate/zlib_deflate.ko > @@ -91,7 +100,8 @@ Examples of using the Linux-provided gdb helpers > Breakpoint 1, btrfs_init_sysfs () at /home/user/linux/fs/btrfs/sysfs.c:36 > 36 btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj); > > - o Dump the log buffer of the target kernel: > +- Dump the log buffer of the target kernel:: > + > (gdb) lx-dmesg > [ 0.000000] Initializing cgroup subsys cpuset > [ 0.000000] Initializing cgroup subsys cpu > @@ -102,19 +112,22 @@ Examples of using the Linux-provided gdb helpers > [ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved > .... > > - o Examine fields of the current task struct: > +- Examine fields of the current task struct:: > + > (gdb) p $lx_current().pid > $1 = 4998 > (gdb) p $lx_current().comm > $2 = "modprobe\000\000\000\000\000\000\000" > > - o Make use of the per-cpu function for the current or a specified CPU: > +- Make use of the per-cpu function for the current or a specified CPU:: > + > (gdb) p $lx_per_cpu("runqueues").nr_running > $3 = 1 > (gdb) p $lx_per_cpu("runqueues", 2).nr_running > $4 = 0 > > - o Dig into hrtimers using the container_of helper: > +- Dig into hrtimers using the container_of helper:: > + > (gdb) set $next = $lx_per_cpu("hrtimer_bases").clock_base[0].active.next > (gdb) p *$container_of($next, "struct hrtimer", "node") > $5 = { > @@ -144,7 +157,7 @@ List of commands and functions > ------------------------------ > > The number of commands and convenience functions may evolve over the time, > -this is just a snapshot of the initial version: > +this is just a snapshot of the initial version:: > > (gdb) apropos lx > function lx_current -- Return current task > diff --git a/Documentation/dev-tools/tools.rst b/Documentation/dev-tools/tools.rst > index 43f7dee..824ae8e 100644 > --- a/Documentation/dev-tools/tools.rst > +++ b/Documentation/dev-tools/tools.rst > @@ -22,3 +22,4 @@ whole; patches welcome! > ubsan > kmemleak > kmemcheck > + gdb-kernel-debugging > Acked-by: Jan Kiszka Looks nicer and less invasive than some of the markdown conversions. Good to know. Jan -- Siemens AG, Corporate Technology, CT RDA ITP SES-DE Corporate Competence Center Embedded Linux