For now we only use the uatomic.h header from liburcu and don't need to link against the actual library, so we don't bother with the PKG_CHECK_MODULES check. If an actual dependency is introduced it will need to be added back, including a non-pkgconfig check for older distributions Like Debian -testing where the current check fails. Signed-off-by: Christoph Hellwig <hch at lst.de> Index: sheepdog/configure.ac =================================================================== --- sheepdog.orig/configure.ac 2012-05-10 16:34:13.471990160 +0200 +++ sheepdog/configure.ac 2012-05-10 16:34:46.639989839 +0200 @@ -77,7 +77,6 @@ AM_MISSING_PROG(AUTOM4TE, autom4te, $mis # Checks for libraries. AC_CHECK_LIB([socket], [socket]) -PKG_CHECK_MODULES([liburcu],[liburcu]) # Checks for header files. AC_FUNC_ALLOCA |