On Sat, May 05, 2018 at 09:21:12PM +0200, damian wrote: > Helllo together, > > Hello everybody, > > is something special to note when kernel build with gcc 8? I receive various > warnings from the objtool: > With GCC 7 works all fine. > > kernel/cgroup/cgroup.o: warning: objtool: parse_cgroup_root_flags()+0x40: > sibling call from callable instruction with modified stack frame > kernel/cgroup/cgroup.o: warning: objtool: cgroup_addrm_files()+0x2a3: sibling > call from callable instruction with modified stack frame > kernel/cgroup/cgroup.o: warning: objtool: > cgroup_apply_control_enable()+0x20b: sibling call from callable instruction > with modified stack frame > kernel/cgroup/cgroup.o: warning: objtool: rebind_subsystems()+0x296: sibling > call from callable instruction with modified stack frame > kernel/cgroup/cgroup.o: warning: objtool: cgroup_sk_alloc_disable()+0x10: > sibling call from callable instruction with modified stack frame > kernel/cgroup/cgroup.o: warning: objtool: > parse_cgroup_root_flags.cold.45()+0xa: call without frame pointer save/setup > kernel/cgroup/cgroup.o: warning: objtool: cgroup_addrm_files.cold.46()+0x17: > call without frame pointer save/setup > kernel/cgroup/cgroup.o: warning: objtool: > cgroup_apply_control_enable.cold.47()+0x24: call without frame pointer > save/setup > kernel/cgroup/cgroup.o: warning: objtool: rebind_subsystems.cold.48()+0x10: > call without frame pointer save/setup > kernel/cgroup/cgroup.o: warning: objtool: > cgroup_sk_alloc_disable.cold.49()+0x7: call without frame pointer save/setup > CC kernel/cgroup/stat.o > CC [M] arch/x86/kvm/../../../virt/kvm/kvm_main.o > arch/x86/kernel/acpi/boot.o: warning: objtool: acpi_register_lapic()+0x10: > sibling call from callable instruction with modified stack frame > arch/x86/kernel/acpi/boot.o: warning: objtool: acpi_map_cpu()+0x2c: sibling > call from callable instruction with modified stack frame > arch/x86/kernel/acpi/boot.o: warning: objtool: > acpi_register_lapic.cold.6()+0x7: call without frame pointer save/setup > arch/x86/kernel/acpi/boot.o: warning: objtool: acpi_map_cpu.cold.7()+0x7: > call without frame pointer save/setup
Thanks, this is a known issue with GCC 8 that I haven't gotten a chance to fix yet. They're related to the fact that GCC 8 is splitting out 'unlikely' code into 'cold' subfunctions in .text.unlikely. I've got some old patches that fix it. Now that GCC 8 is out, I'll need get the patches dusted off and cleaned up for merging. -- Josh
