Date:	Wed, 10 Aug 2016 09:03:22 +0200
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Jani Nikula <jani.nikula@...el.com>
Subject: Re: [PATCH 10/10] docs: Sphinxify gdb-kernel-debugging.txt and move
 to dev-tools

On 2016-08-09 01:35, Jonathan Corbet wrote:
> Cc: Jan Kiszka <jan.kiszka@...mens.com>
> Signed-off-by: Jonathan Corbet <corbet@....net>
> ---
>  .../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 <jan.kiszka@...mens.com>

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

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