On Thu, Jan 14, 2021 at 8:20 AM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote: > > On Thu, Jan 14, 2021 at 12:27 AM Nick Desaulniers > <ndesaulniers@xxxxxxxxxx> wrote: > > > > Sedat, > > Thanks for testing, and congrats on https://lwn.net/Articles/839772/. > > I always appreciate you taking the time to help test my work, and > > other Clang+Linux kernel patches! > > > > Hi Nick, > > cool, again in the top 15 :-). > > I should ask Mr. Corbet for a LWN subscription. > > > On Wed, Jan 13, 2021 at 1:24 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote: > > > > > > On Wed, Jan 13, 2021 at 1:32 AM Nick Desaulniers > > > <ndesaulniers@xxxxxxxxxx> wrote: > > > > > > > > --- a/Makefile > > > > +++ b/Makefile > > > > @@ -826,12 +826,16 @@ else > > > > DEBUG_CFLAGS += -g > > > > endif > > > > > > > > -ifneq ($(LLVM_IAS),1) > > > > -KBUILD_AFLAGS += -Wa,-gdwarf-2 > > > > +dwarf-version-$(CONFIG_DEBUG_INFO_DWARF2) := 2 > > > > +dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4 > > > > +DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y) > > > > ^ DEBUG_CFLAGS are set for everyone (all toolchains) if > > CONFIG_DEBUG_INFO is defined. > > > > > > +ifneq ($(dwarf-version-y)$(LLVM_IAS),21) > > > > ^ "If not using dwarf 2 and LLVM_IAS=1", ie. CONFIG_DEBUG_INFO_DWARF5 > > && CONFIG_CC_IS_GCC > > > > OK, I know DWARF v2 and LLVM_IAS=1 is broken. > > Looks like DWARF v5 with GCC v10.2.1 and binutils v2.35.1 is currently > (here) no good choice. > > > > > +# Binutils 2.35+ required for -gdwarf-4+ support. > > > > +dwarf-aflag := $(call as-option,-Wa$(comma)-gdwarf-$(dwarf-version-y)) > > > > +ifdef CONFIG_CC_IS_CLANG > > > > ^ "if clang" > > > > > > +DEBUG_CFLAGS += $(dwarf-aflag) > > > > endif > > > > > > Why is that "ifdef CONFIG_CC_IS_CLANG"? > > > > That's what Arvind requested on v2, IIUC: > > https://lore.kernel.org/lkml/X8psgMuL4jMjP%2FOy@xxxxxxxxxxxxxxxxxx/ > > > > > When I use GCC v10.2.1 DEBUG_CFLAGS are not set. > > > > You should have -gdwarf-4 (and not -Wa,-gwarf-4) set for DEBUG_CFLAGS > > when compiling with GCC and enabling CONFIG_DEBUG_INFO_DWARF4. Can you > > please confirm? (Perhaps you may have accidentally disabled > > CONFIG_DEBUG_INFO by rerunning `make defconfig`?) > > > > $ egrep 'CC_IS_|LD_IS|BTF|DWARF' > config-5.11.0-rc3-5-amd64-gcc10-llvm11 | grep ^CONFIG > CONFIG_CC_IS_GCC=y > CONFIG_LD_IS_LLD=y > CONFIG_DEBUG_INFO_DWARF4=y > CONFIG_DEBUG_INFO_BTF=y > CONFIG_DEBUG_INFO_BTF_MODULES=y > > $ grep '\-Wa,-gdwarf-4' build-log_5.11.0-rc3-5-amd64-gcc10-llvm11.txt > | wc -l > 156 I wonder why I see GNU/as here (see above CONFIG_LD_IS_LLD=y)? $ llvm-dwarfdump-11 vmlinux | head -20 | egrep 'debug_info|format|version|DW_AT_producer' vmlinux: file format elf64-x86-64 .debug_info contents: 0x00000000: Compile Unit: length = 0x0000001e, format = DWARF32, version = 0x0004, abbr_offset = 0x0000, addr_size = 0x08 (next unit at 0x00000022) DW_AT_producer ("GNU AS 2.35.1") 0x00000022: Compile Unit: length = 0x0000c1d2, format = DWARF32, version = 0x0004, abbr_offset = 0x0012, addr_size = 0x08 (next unit at 0x0000c1f8) DW_AT_producer ("GNU C89 10.2.1 20210110 -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mno-fp-ret-in-387 -mpreferred-stack-boundary =3 -mskip-rax-setup -mtune=generic -mno-red-zone -mcmodel=kernel -mindirect-branch=thunk-extern -mindirect-branch-register -mrecord-mcount -mfentry -march=x86-64 -g -g dwarf-4 -O2 -std=gnu90 -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -falign-jumps=1 -falign-loops=1 -fno-asynchronous-unwind-tables -fno-jump-tables -fno-de lete-null-pointer-checks -fno-allow-store-data-races -fstack-protector-strong -fno-strict-overflow -fstack-check=no -fconserve-stack -fcf-protection=none -fno-stack-pr otector") Maybe, I should set all LLVM utils and linker manually, not using LLVM=1. - Sedat -
