When doing non-clean builds and switching between CONFIG_LTO=n and CONFIG_LTO=y, the build system (correctly) didn't notice that assembly and LTO-excluded C object files were rewritten in place by objtool (to add the .orc_unwind* sections), since their build command lines were the same between CONFIG_LTO=y and CONFIG_LTO=n. The objtool step would fail: vmlinux.o: warning: objtool: file already has .orc_unwind section, skipping make: *** [Makefile:1194: vmlinux] Error 255 Avoid this by making sure the build will see a difference between an LTO and non-LTO build (by including "-fno-lto" in KBUILD_*FLAGS). This will get ignored when CC_FLAGS_LTO is present, and will not be included at all when CONFIG_LTO=n.
Unified · Split
| @@ -910,7 +910,8 @@ KBUILD_LDFLAGS += -mllvm -import-instr-limit=5 · 909 unmodified lines | ||
| 910 | 910 | endif |
| 911 | 911 | |
| 912 | 912 | ifdef CONFIG_LTO |
| 913 | −KBUILD_CFLAGS += $(CC_FLAGS_LTO) | |
| 913 | +KBUILD_CFLAGS += -fno-lto $(CC_FLAGS_LTO) | |
| 914 | +KBUILD_AFLAGS += -fno-lto | |
| 914 | 915 | export CC_FLAGS_LTO |
| 915 | 916 | endif |
| 916 | 917 | |