Re: [PATCH v3 3/3] perf probe: Show better error message when failed to find variable

[He Kuang]

Hi, Ingo

On 2015/5/11 17:30, Ingo Molnar wrote:
> * He Kuang <hekuang@xxxxxxxxxx> wrote:
>
> > Indicate to check variable location range in error message when we got
> > failed to find the variable.
> >
> > Before this patch:
> >
> >    $ perf probe --add 'generic_perform_write+118 bytes'
> >    Failed to find the location of bytes at this address.
> >     Perhaps, it has been optimized out.
> >      Error: Failed to add events.
> >
> > After this patch:
> >    $ perf probe --add 'generic_perform_write+118 bytes'
> >    Failed to find the location of bytes at this address.
> What does this sentence mean? I thought 'address' means 'location of
> bytes'. So the address identifies the location and obviously we know
> that. So this message wants to say something else.

'generic_perform_write' is a function name, while 'bytes' is a local
variable in this function. Maybe the variable I chose make you confused.

This maybe clear:
  Failed to find the location of 'bytes' at this address.

> >     Perhaps, it has been optimized out.
> >     Use -V with --range option to show variable location range.
> This suggestion is useful.
>
> >      Error: Failed to add events.
> Thanks,
>
> 	Ingo
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