Re: [PATCH] perf util: Display warning when perf report/annotate is missing some libs

["Jin, Yao" <yao.jin@linux.intel.com>]

Hi Jiri,

I'm still thinking it's worth displaying the warning when perf missing 
some libraries.

Somebody just told me that perf didn't work well. While after some 
investigations, I found it's just missing some libraries when building 
the perf.

But I have spent some time on getting the root cause. If with this 
patch, it should be very easily to know that.

Thanks
Jin Yao

On 1/12/2018 10:22 AM, Jin, Yao wrote:
> 
> 
> On 1/11/2018 11:30 PM, Jiri Olsa wrote:
>> On Thu, Jan 11, 2018 at 07:03:06PM +0800, Jin Yao wrote:
>>> We keep having bug reports that when users build perf on their own,
>>
>> we already have same warnings during the build
>>
> 
> Yes, there will be warnings displayed during the build if some libraries 
> are missing.
> 
> While I do find the users (especially the new perf user) don't notice 
> the warning. They only care about the success of build.
> 
> Once they use this perf version and find something working strangely, 
> they will say that perf may have bug. :(
> 
>>> but they don't install some needed libraries like libelf, 
>>> libbfd/libibery.
>>
>> how about saying that in the symbol column,
>> instead of poluting report's output, like:
>>
>>     $ perf report --stdio
>>
>>     # Overhead  Command  Shared Object     Symbol (disabled)
>>     # ........  .......  ................  ......................
>>
> 
> I just think it'd better provide some hints to user. For example, 
> "symbol is disabled and you need to install libelf/xxx", say something 
> like that.
> 
> But it looks the column can't contain too much information (i.e. no more 
> space to contain the entire hints).
> 
> Any idea? Or just add this warning in verbose mode?
> 
>> also your change does not affect tui mode
>>
>> annotation for some reason does not start at all.. could be
>> little more verbose ;-)
>>
>> jirka
>>
> 
> Yes, it doesn't affect tui mode.
> 
> Or we just add this warning in verbose mode?
> 
> e.g. perf report -v?
> 
> Thanks
> Jin Yao