linux-kernel - Re: [PATCH] perf report: Fix no libunwind compiled warning break s390 issue

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Date:   Wed, 8 Jan 2020 11:27:08 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com, tmricht@...ux.ibm.com
Subject: Re: [PATCH] perf report: Fix no libunwind compiled warning break
 s390 issue

On Wed, Jan 08, 2020 at 03:17:45AM +0800, Jin Yao wrote:
> Commit 800d3f561659 ("perf report: Add warning when libunwind not compiled in")
> breaks the s390 platform. S390 uses libdw-dwarf-unwind for call chain
> unwinding and had no support for libunwind.
> 
> So the warning "Please install libunwind development packages during the perf build."
> caused the confusion even if the call-graph is displayed correctly.
> 
> This patch adds checking for HAVE_DWARF_SUPPORT, which is set when
> libdw-dwarf-unwind is compiled in.
> 
> Fixes: 800d3f561659 ("perf report: Add warning when libunwind not compiled in")
> 
> Reviewed-by: Thomas Richter <tmricht@...ux.ibm.com>
> Tested-by: Thomas Richter <tmricht@...ux.ibm.com>
> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>

perfect, I have the same change prepared for sending, but it's
together with making libdw default dwarf unwinder, which I'm still
not sure we want to do, so it all got posponed ;-)

would you guys be ok with that? with having libdw picked up as default dwarf unwinder..

for the patch:

Acked-by: Jiri Olsa <jolsa@...hat.com>

thanks,
jirka

> ---
>  tools/perf/builtin-report.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> index de988589d99b..66cd97cc8b92 100644
> --- a/tools/perf/builtin-report.c
> +++ b/tools/perf/builtin-report.c
> @@ -412,10 +412,10 @@ static int report__setup_sample_type(struct report *rep)
>  				PERF_SAMPLE_BRANCH_ANY))
>  		rep->nonany_branch_mode = true;
>  
> -#ifndef HAVE_LIBUNWIND_SUPPORT
> +#if !defined(HAVE_LIBUNWIND_SUPPORT) && !defined(HAVE_DWARF_SUPPORT)
>  	if (dwarf_callchain_users) {
> -		ui__warning("Please install libunwind development packages "
> -			    "during the perf build.\n");
> +		ui__warning("Please install libunwind or libdw "
> +			    "development packages during the perf build.\n");
>  	}
>  #endif
>  
> -- 
> 2.17.1
>