#+TITLE: Clear Kernel Build Error? Fix It
#+DATE: <2022-11-04 五>
#+DESCRIPTION: arch/x86/kernel/cpu/intel_epb.c:171:2: error: call to undeclared function 'sched _set_itmt_power_ratio'

when I compile [[https://github.com/clearlinux-pkgs/linux][clear]] kernel with LLVM enabled, I got this error:
#+BEGIN_SRC text
  arch/x86/kernel/cpu/intel_epb.c:172:2: error: call to undeclared function 'sched_set_itmt_power_ratio';
  ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
          sched_set_itmt_power_ratio(256 - val * 2, cpu);
          ^
  arch/x86/kernel/cpu/intel_epb.c:172:2: note: did you mean 'sched_set_itmt_core_prio'?
  ./arch/x86/include/asm/topology.h:189:20: note: 'sched_set_itmt_core_prio' declared here
  static inline void sched_set_itmt_core_prio(int prio, int core_cpu)
                     ^
  1 error generated.
#+END_SRC

it's obvious that the [[https://github.com/clearlinux-pkgs/linux/blob/main/0128-itmt_epb-use-epb-to-scale-itmt.patch][sched_set_itmt_power_ratio]] function is undeclared
so I added the following like the function on top of it
and it is able to compile :)
#+BEGIN_SRC diff
--- /home/gentoo/linux/topology.h
+++ arch/x86/include/asm/topology.h
@@ -189,6 +189,9 @@
 static inline void sched_set_itmt_core_prio(int prio, int core_cpu)
 {
 }
+static inline void sched_set_itmt_power_ratio(int prio, int core_cpu)
+{
+}
 static inline int sched_set_itmt_support(void)
 {
        return 0;
#+END_SRC

Notice: I'm ignorant about C programming, so if anything's wrong, please contact me