Re: [patch 2/2] Linux Kernel Markers - Create modpost file

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 04 Dec 2007 13:18:47 -0500
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> This adds some new magic in the MODPOST phase for CONFIG_MARKERS.
> Analogous to the Module.symvers file, the build will now write a
> Module.markers file when CONFIG_MARKERS=y is set.  This file lists
> the name, defining module, and format string of each marker,
> separated by \t characters.  This simple text file can be used by
> offline build procedures for instrumentation code, analogous to
> how System.map and Module.symvers can be useful to have for
> kernels other than the one you are running right now.
> 
> The strings are made easy to extract by having the __trace_mark macro
> define the name and format together in a single array called __mstrtab_*
> in the __markers_strings section.  This is straightforward and reliable
> as long as the marker structs are always defined by this macro.  It is
> an unreasonable amount of hairy work to extract the string pointers from
> the __markers section structs, which entails handling a relocation type
> for every machine under the sun.
> 
> Mathieu :
> - Ran through checkpatch.pl
> 
> ...
>
> --- linux-2.6-lttng.orig/scripts/mod/modpost.c	2007-11-21 20:54:17.000000000 -0500
> +++ linux-2.6-lttng/scripts/mod/modpost.c	2007-11-21 21:19:19.000000000 -0500
> @@ -11,6 +11,8 @@
>   * Usage: modpost vmlinux module1.o module2.o ...
>   */
>  
> +#define _GNU_SOURCE

Why was the mystery addition of _GNU_SOURCE made?

> +#include <stdio.h>
>  #include <ctype.h>
>  #include "modpost.h"
>  #include "../../include/linux/license.h"
> @@ -424,6 +426,8 @@ static int parse_elf(struct elf_info *in

These two patches are unfortunately large, intrusive and tricky to be
turning up in -rc4.