[lttng-dev] [PATCH lttng-tools 2/2] Fix: Missing libs dependencies in configure check for lttng-ust-ctl

[Mathieu Desnoyers]

* Christian Babeux (christian.babeux at efficios.com) wrote:
> The lttng-ust-ctl library depends on liburcu-{common,bp,cds}.
> The AC_CHECK_LIBRARY macro can't automatically resolve dependents
> libraries (ala libtool), so any additionnals dependencies must
> be manually specified.
> 
> Also, the AC_CHECK_LIB action-if-found case for the lttng-ust-ctl
> check is modified to have a similar behavior as the default action,
> which is to define HAVE_LIBxxx and append -lxxx to $LIBS, *except*
> for the later step. This is to ensure that any future addition of
> AC_CHECK_LIB after the one for lttng-ust-ctl will not need to append
> the liburcu dependencies or fail unexpectedly.

not sure I understand why all the changes you are doing are needed. What
happens if you just do:

-             [AC_MSG_ERROR([Cannot find LTTng-UST. Use [LDFLAGS]=-Ldir to specify its location, or specify --disable-lttng-ust to build lttng-tools without LTTng-UST support.])]
+             [AC_MSG_ERROR([Cannot find LTTng-UST. Use [LDFLAGS]=-Ldir to specify its location, or specify --disable-lttng-ust to build lttng-tools without LTTng-UST support.])],
+             [-lurcu-common -lurcu-bp -lurcu-cds]

?

> 
> Signed-off-by: Christian Babeux <christian.babeux at efficios.com>
> ---
>  configure.ac | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index 3a023cd..e4b9eb1 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -138,13 +138,16 @@ AC_ARG_ENABLE(lttng-ust,
>  	lttng_ust_support=$enableval, lttng_ust_support=yes)
>  
>  AS_IF([test "x$lttng_ust_support" = "xyes"], [
> -	AC_CHECK_LIB([lttng-ust-ctl], [ustctl_create_session], [],
> -		[AC_MSG_ERROR([Cannot find LTTng-UST. Use [LDFLAGS]=-Ldir to specify its location, or specify --disable-lttng-ust to build lttng-tools without LTTng-UST support.])]
> +	AC_CHECK_LIB([lttng-ust-ctl], [ustctl_create_session],
> +		[
> +			AC_DEFINE([HAVE_LIBLTTNG_UST_CTL], [1], [has LTTng-UST control support])

wasn't HAVE_LIBLTTNG_UST_CTL already defined by the AM_CONDITIONAL below ?

> +			lttng_ust_ctl_found=yes

why are you adding this ?

> +		],
> +		[AC_MSG_ERROR([Cannot find LTTng-UST. Use [LDFLAGS]=-Ldir to specify its location, or specify --disable-lttng-ust to build lttng-tools without LTTng-UST support.])],
> +		[-lurcu-common -lurcu-bp -lurcu-cds]
>  	)
>  ])
> -
> -AM_CONDITIONAL([HAVE_LIBLTTNG_UST_CTL], [ test "x$ac_cv_lib_lttng_ust_ctl_ustctl_create_session" = "xyes" ])
> -
> +AM_CONDITIONAL([HAVE_LIBLTTNG_UST_CTL], [test "x$lttng_ust_ctl_found" = xyes])

why are you changing this line ?

Thanks,

Mathieu


>  AC_CHECK_FUNCS([sched_getcpu sysconf])
>  
>  # check for dlopen
> -- 
> 1.7.11.3
> 
> 
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> lttng-dev at lists.lttng.org
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com