JFTR I did build the urcu and ltt-control on same machine and urcu build went ok, but ltt-control failed. So there might be something broken.
Although yes, more generally there could be a problem with difference between build machines, so --disable flag might be helpful. O. -- Ondřej Surý <[email protected]> Knot DNS (https://www.knot-dns.cz/) – a high-performance DNS server > On 24. 5. 2014, at 0:21, Jon Bernard <[email protected]> wrote: > > * Mathieu Desnoyers <[email protected]> wrote: >> Hi, >> >> I recently stumbled on this patch: >> >> http://sprunge.us/jYcJ >> >> It overrides the generated config.h to ensure the >> "dmb" instruction is not used. >> >> However, the proper checks seems to be in place within >> configure.ac to automatically detect whether to use dmb >> or not: >> >> # ARM-specific checks >> AS_IF([test "x$ARCHTYPE" = "xarm"],[ >> AC_MSG_CHECKING([for dmb instruction]) >> AC_COMPILE_IFELSE([AC_LANG_SOURCE([[ >> int main() >> { >> asm volatile("dmb":::"memory"); >> return 0; >> } >> ]]) >> ],[ >> AC_MSG_RESULT([yes]) >> AC_DEFINE([CONFIG_RCU_ARM_HAVE_DMB], [1]) >> ],[ >> AC_MSG_RESULT([no]) >> ]) >> ]) >> >> My thinking here is that perhaps inappropriate compiler flags >> are used when the compiler is invoked from within "configure", >> which leads it to think that it targets an ARMv7+ with dmb. >> The Debian "armel" architecture AFAIU needs to target older >> ARM architectures. > > I also wonder if there are some differences between of the arm build > machines. I don't have shell access to the machine on which urcu was > built so I cannot check, but perhaps that particular machine has dmb. > >> It would be much better to fix the compiler flags passed to >> configure and let urcu autodetection do what it is intended >> to do rather than override the generated file. > > I'll gather and post the compiler flags used for urcu and we'll see. > > -- > Jon
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