On Tue, Apr 18, 2017 at 11:52:41AM -0700, Andi Kleen wrote: > Josh Poimboeuf <[email protected]> writes: > > > > The error is working as designed. gcc < 4.6.0 doesn't have -mfentry, so > > it fails the above check on x86. Can you add a skip rule? It should > > skip building the following case: > > > > x86 && ((gcc < 4.6.0) || (CONFIG_X86_32 and !CONFIG_DYNAMIC_FTRACE)) > > && CONFIG_FUNCTION_GRAPH_TRACER && CONFIG_CC_OPTIMIZE_FOR_SIZE > > This will also break everyone's randconfig builds. The better way > would be to check this in the Makefile and disable one of the options
I don't know how to disable a config option from the Makefile like that. Any ideas? BTW, I think it will only break randconfigs for old versions of gcc, before 4.6.0. The error message isn't quite right. I just noticed the FUNCTION_GRAPH_TRACER config has: depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE which means that X86_32 and CC_OPTIMIZE_FOR_SIZE can never be set with FUNCTION_GRAPH_TRACER. So the error message could be simplified to: #error The following combination is not supported: (compiler missing -mfentry) && CONFIG_FUNCTION_GRAPH_TRACER && CONFIG_CC_OPTIMIZE_FOR_SIZE -- Josh
