On Fri, 11 Sep 2009 21:43:42 -0700 "H. Peter Anvin" <hpa@xxxxxxxxxx> wrote: > On 09/11/2009 08:49 PM, Arjan van de Ven wrote: > > On Fri, 11 Sep 2009 14:55:25 -0700 (PDT) > > Roland McGrath <roland@xxxxxxxxxx> wrote: > > > >>> That's a bit of a mouthful. Did you consider a runtime probe with > >>> scripts/Kbuild.include's try-run, cc-option, etc? > >> > >> I did not see any precedent in the sources for using those to test > >> for features by compiling particular test sources (i.e. in autoconf > > > > look at the stackprotector flags.. they work this way already. > > It gets done once per kernel build... > > > > That works for flags, but not for the presence of builtin functions. > You can't even just try compiling something, since it will turn into > an ordinary function if not present... not obvious until link. "-DGG_HAS_UNREACHABLE" is a compiler flag ;-) and the shell script can just do a "nm" on the resulting .o file to detect if it turned into a function call... entirely possible. -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
