Re: [PATCH] modpost: Fix secondary errors seen if a single module build fails

[Michal Marek <mmarek@suse.cz>]

Dne 15.9.2013 06:39, Guenter Roeck napsal(a):
> Commit ea4054a23 (modpost: handle huge numbers of modules) added
> support for building a large number of modules.
> 
> Unfortunately, the commit changed the semantics of the makefile: Instead of
> passing only existing object files to modpost, make now passes all expected
> object files. If make was started with option -i, this results in a modpost
> error if a single file failed to build.
> 
> Example with the current btrfs build falure on m68k:
> 
> fs/btrfs/btrfs.o: No such file or directory
> make[1]: [__modpost] Error 1 (ignored)
> 
> This error is followed by lots of errors such as:
> 
> m68k-linux-gcc: error: arch/m68k/emu/nfcon.mod.c: No such file or directory
> m68k-linux-gcc: fatal error: no input files
> compilation terminated.
> make[1]: [arch/m68k/emu/nfcon.mod.o] Error 1 (ignored)
> 
> This doesn't matter much for normal builds, but it is annoying for builds
> started with "make -i" due to the large number of secondary errors.
> Those errors unnececessarily clog any error log and make it difficult
> to find the real errors in the build.
> 
> Fix the problem by only passing existing object files to modpost.
> 
> Cc: Rusty Russell <rusty@rustcorp.com.au>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  scripts/Makefile.modpost |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
> index 8dcdca2..387c806 100644
> --- a/scripts/Makefile.modpost
> +++ b/scripts/Makefile.modpost
> @@ -81,7 +81,8 @@ modpost = scripts/mod/modpost                    \
>  
>  # We can go over command line length here, so be careful.
>  quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
> -      cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/.o/' | $(modpost) -s -T -
> +      cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/.o/' | \
> +	while read a; do [ -f $$a ] && echo $$a; done | $(modpost) -s -T -

Can you do this filtering only if make -i is used ('i' is present in
$(MAKEFLAGS)), to not hide potential buildsystem bugs? Regarding shell
loop vs. ls, maybe the cleanest way would be to add an option to modpost
to ignore missing files.

Thanks,
Michal