On Wed, Mar 22, 2017 at 08:51:53AM +0100, Ingo Molnar wrote: > > +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && \ > > + !defined(CC_USING_FENTRY) && \ > > + !defined(CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE) > > +# error Your compiler does not support function graph tracing > > +#endif > > Might make sense to add the compiler option that is missing, i.e. something > like: > > # error Your compiler does not support function graph tracing (-mfentry) > > (or whatever compiler feature is missing.)
I left it vague because otherwise it would need a paragraph :-) After Steven's latest patches which port fentry to x86-32, I think the precise version would be: # error The following combination is not supported: ((compiler missing -mfentry) || (CONFIG_X86_32 and !CONFIG_DYNAMIC_FTRACE)) && CONFIG_FUNCTION_GRAPH_TRACER && CONFIG_CC_OPTIMIZE_FOR_SIZE. -- Josh
