Re: Build issues due to patch "gprofng: a new GNU profiler" – CLOCK_MONOTONIC_RAW not defined

[Vladimir Mezentsev]

On 3/14/22 03:57, Tobias Burnus wrote:
> Hi Vladimir, hi Nick,
>
> Friday's commit "gprofng: a new GNU profiler",
> https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=bb368aad297fe3ad40cf397e6fc85aa471429a28 
>
>
> broke the build here (build server using on purpose an older 
> Linux/glibc):
>
> gprofng/libcollector/gethrtime.c:35:26: error: 'CLOCK_MONOTONIC_RAW' 
> undeclared (first use in this function); did you mean 'CLOCK_MONOTONIC'?
>    int r = clock_gettime (CLOCK_MONOTONIC_RAW, &tp);
>                           ^~~~~~~~~~~~~~~~~~~
>                           CLOCK_MONOTONIC
>
> According to https://linux.die.net/man/2/clock_gettime:
>
>   CLOCK_MONOTONIC_RAW (since Linux 2.6.28; Linux-specific)
>     Similar to CLOCK_MONOTONIC, but provides access to a raw 
> hardware-based
>     time that is not subject to NTP adjustments or the incremental
>     adjustments performed by adjtime(3).
>
> Thus, it seems as if either a config check or a much
> simpler patch as the following is needed:
>
> --- a/gprofng/libcollector/gethrtime.c
> +++ b/gprofng/libcollector/gethrtime.c
> @@ -34,3 +34,7 @@ linux_gethrtime ()
>    hrtime_t rc = 0;
> +#ifdef CLOCK_MONOTONIC_RAW
>    int r = clock_gettime (CLOCK_MONOTONIC_RAW, &tp);
> +#else
> +  int r = clock_gettime (CLOCK_MONOTONIC, &tp);
> +#endif
>    if (r == 0)
>
> --- a/gprofng/src/gethrtime.c
> +++ b/gprofng/src/gethrtime.c
> @@ -161,3 +161,7 @@ gethrtime (void)
>     */
> +#ifdef CLOCK_MONOTONIC_RAW
>    int r = clock_gettime (CLOCK_MONOTONIC_RAW, &tp);
> +#else
> +  int r = clock_gettime (CLOCK_MONOTONIC, &tp);
> +#endif
>    if (r == 0)
>
>  * * *
>
> Additionally, the build fails with the link error:
>    gprofng/src/gethrtime.c:131: undefined reference to `clock_gettime'
>
> The problem seems to be what the 'clock_gettime(3)' man page states:
>        Link with -lrt (only for glibc versions before 2.17).
>
> Please consider as fix to copy the following check from 
> libbacktrace/configure.ac:
>
> # Check for the clock_gettime function.
> AC_CHECK_FUNCS(clock_gettime)
> ...
> AC_SUBST(CLOCK_GETTIME_LINK)


  Hi Tobia,
Your fixes look good to me.
Could you apply these fixes.
I can prepare a patch but I cannot  build on your configuration.

Thank you,
-Vladimir



>
>
> Thanks,
>
> Tobias
>
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