On Fri 2016-02-05 09:48:03, Steven Rostedt wrote: > On Fri, 5 Feb 2016 15:05:17 +0100 > Petr Mladek <pmladek@xxxxxxxx> wrote: > > > On Mon 2016-01-25 16:29:54, Torsten Duwe wrote: > > > diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c > > > index ef8b916..29b7014 100644 > > > --- a/arch/powerpc/kernel/ftrace.c > > > +++ b/arch/powerpc/kernel/ftrace.c > > > @@ -28,6 +28,11 @@ > > > > > > > > > #ifdef CONFIG_DYNAMIC_FTRACE > > > +#if defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && defined(CONFIG_PPC64) && \ > > > + !defined(CC_USING_MPROFILE_KERNEL) > > > +#error "DYNAMIC_FTRACE_WITH_REGS requires working -mprofile-kernel" > > > +#endif > > > > CONFIG_DYNAMIC_FTRACE_WITH_REGS is automatically enabled when > > both CONFIG_DYNAMIC_FTRACE and HAVE_DYNAMIC_FTRACE_WITH_REGS > > are enabled. > > > > Therefore it is not possible to build kernel with broken gcc > > and DYNAMIC_FTRACE. > > > > IMHO, we need to allow to explicitely disable DYNAMIC_FTRACE_WITH_REGS > > if the compiler is broken to get around this build error. > > > > We either need to define DYNAMIC_FTRACE_WITH_REGS as a proper > > bool with description, help text, ... Or we need a way to > > explicitely disable HAVE_DYNAMIC_FTRACE_WITH_REGS. Or something > > like this. > > > > You mean something like this? > > (not tested) > > -- Steve > > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index e45db6b0d878..19377bacebfc 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -470,6 +470,19 @@ config DYNAMIC_FTRACE_WITH_REGS > def_bool y > depends on DYNAMIC_FTRACE > depends on HAVE_DYNAMIC_FTRACE_WITH_REGS > + depends on !DISABLE_DYNAMIC_FTRACE_WITH_REGS > + > +config DISABLE_DYNAMIC_FTRACE_WITH_REGS > + bool "Force build to not have function tracer pass in registers" > + depends on DYNAMIC_FTRACE > + depends on HAVE_DYNAMIC_FTRACE_WITH_REGS > + help > + If the architecture supports passing in registers to the function > + tracer, then that is automatically enabled. But there may be some > + compilers out there that are broken and cause this to fail. > + This option makes the build think that the architecture does not > + support the register passing and allows the build to work even > + with compilers that do not support the feature.g s/feature.g/feature/ > config FUNCTION_PROFILER > bool "Kernel function profiler" It works but the extra option and reverse logic makes things even more complicated. Whem I think about it, the change below does similar job and looks more strightforwad: diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index a138f6d..de6dab0 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -449,7 +449,7 @@ config PROBE_EVENTS def_bool n config DYNAMIC_FTRACE - bool "enable/disable function tracing dynamically" + bool "Enable/Disable function tracing dynamically" depends on FUNCTION_TRACER depends on HAVE_DYNAMIC_FTRACE default y @@ -472,9 +472,17 @@ config DYNAMIC_FTRACE otherwise has native performance as long as no tracing is active. config DYNAMIC_FTRACE_WITH_REGS - def_bool y + bool "Pass registers to function tracer" depends on DYNAMIC_FTRACE depends on HAVE_DYNAMIC_FTRACE_WITH_REGS + default y + help + This option enables passing the current state of processor + registers to the function tracer. It allows to do a more + detailed analyze and print more information. + + Say Y here if you are unsure. The only exception is if + you want to pass a build error caused by a broken compiler. config FUNCTION_PROFILER bool "Kernel function profiler" I made "enable/disable" uppercase because it looked weird in context of other descritions. Best Regards, Petr -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
