Re: [PATCH v0 07/71] perf tools: Record whether a dso is 64-bit

From: Arnaldo Carvalho de Melo
Date: Thu Dec 12 2013 - 15:02:00 EST


Em Thu, Dec 12, 2013 at 12:16:16PM -0700, David Ahern escreveu:
> On 12/12/13, 12:05 PM, Arnaldo Carvalho de Melo wrote:
>
> >Well, if we can pass somehow the magic number of an executable mmap
> >in the PERF_RECORD_MMAP2 record, we would be able, together with the
> >data we already have in the perf.data header (uname in a live session),
> >to figure that out, no?
>
> Sure, but any kernel-side only solution will be extremely limited in
> user base for years.

You mean it will take time for the kernel with this feature to become
widespread?

Sure, but how do you propose to properly implement this using existing
facilities?

I can't think of any way that doesn't requires having access to the file
referenced via PERF_RECORD_{MMAP,MMAP2}, in userspace, and that is racy.

For older kernels, that doesn't support this, we can do as I think you
envision, but that doesn't precludes trying to put in place a more
robust solution.

- Arnaldo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/