On Fri, 24 Jul 2020 19:55:00 +0200 Oscar Carter <oscar.carter@xxxxxxx> wrote: > > Which one of the above is this patch set for? > > This patch is the result of a warning obtained with the following: > > make allmodconfig ARCH=powerpc > make ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnu- -j4 > > And with the -Wcast-function-type enabled in the top level makefile. Looking into powerpc I found this: arch/powerpc/include/asm/ftrace.h: #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS #define ARCH_SUPPORTS_FTRACE_OPS 1 #endif arch/powerpc/Kconfig: select HAVE_DYNAMIC_FTRACE_WITH_REGS if MPROFILE_KERNEL [..] config MPROFILE_KERNEL depends on PPC64 && CPU_LITTLE_ENDIAN && FUNCTION_TRACER def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -I$(srctree)/include -D__KERNEL__) So, it looks like you need to be 64bit PowerPC, Little Endian, and gcc needs to support -mprofile. Otherwise, it falls back to the old way that does the type casting. If you are really concerned about this, I would recommend adding support to the architecture you care about, and then this will no longer be an issue. The funny part is, you can still add support for ftrace_ops, without adding support for DYNAMIC_FTRACE_WITH_REGS, if you only care about not having to do that typecast. My NAK still stands. I wont let an intrusive patch be added to the ftrace core code to deal with an unsupported feature in an architecture. I would be will to add that linker trick to remove the warning. Or we just use that warning as incentive to get architecture developers to implement this feature ;-) -- Steve
