Hi Palmer, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 7a56db0299f9d43b4fe076838150c5cc293df131 commit: 52e7c52d2ded5908e6a4f8a7248e5fa6e0d6809a RISC-V: Stop relying on GCC's register allocator's hueristics date: 7 weeks ago config: riscv-allnoconfig (attached as .config) compiler: riscv64-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout 52e7c52d2ded5908e6a4f8a7248e5fa6e0d6809a # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=riscv If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): arch/riscv/kernel/stacktrace.c: In function 'walk_stackframe': 78 | sp = sp_in_global; | ^~~~~~~~~~~~ arch/riscv/kernel/stacktrace.c:78:8: note: each undeclared identifier is reported only once for each function it appears in vim +/sp_in_global +78 arch/riscv/kernel/stacktrace.c 67 68 static void notrace walk_stackframe(struct task_struct *task, 69 struct pt_regs *regs, bool (*fn)(unsigned long, void *), void *arg) 70 { 71 unsigned long sp, pc; 72 unsigned long *ksp; 73 74 if (regs) { 75 sp = user_stack_pointer(regs); 76 pc = instruction_pointer(regs); 77 } else if (task == NULL || task == current) { 79 pc = (unsigned long)walk_stackframe; 80 } else { 81 /* task blocked in __switch_to */ 82 sp = task->thread.sp; 83 pc = task->thread.ra; 84 } 85 86 if (unlikely(sp & 0x7)) 87 return; 88 89 ksp = (unsigned long *)sp; 90 while (!kstack_end(ksp)) { 91 if (__kernel_text_address(pc) && unlikely(fn(pc, arg))) 92 break; 93 pc = (*ksp++) - 0x4; 94 } 95 } 96 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org