Re: [PATCH] objtool: Fix Makefile to properly see if libelf is supported

[Josh Poimboeuf]

On Wed, Apr 20, 2016 at 11:32:35AM -0400, Steven Rostedt wrote:
> When doing a make allmodconfig, I hit the following compile error:
> 
> In file included from builtin-check.c:32:0:
> elf.h:22:18: fatal error: gelf.h: No such file or directory
> compilation terminated.
> In file included from special.h:22:0,
>                  from special.c:26:
> elf.h:22:18: fatal error: gelf.h: No such file or directory
> compilation terminated.
> In file included from elf.c:30:0:
> elf.h:22:18: fatal error: gelf.h: No such file or directory
> compilation terminated.
> mv: cannot stat 'tools/objtool/.elf.o.tmp': No such file or directory
> tools/build/Makefile.build:77: recipe for target 'tools/objtool/elf.o' failed
> make[4]: *** [tools/objtool/elf.o] Error 1
> make[4]: *** Waiting for unfinished jobs....
> 
> Digging into it, it appears that the $(shell ..) command in the Makefile does
> not give the proper result when it fails to find -lelf, and continues to
> compile objtool.
> 
> Instead, use the "try-run" makefile macro to perform the test. This gives a
> proper result for both cases.
> 
> Fixes: 442f04c34a1a4 ("objtool: Add tool to perform compile-time stack metadata validation")
> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>

Thanks!

Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

-- 
Josh