On Thu, Nov 15, 2018 at 1:01 PM Nadav Amit <namit@xxxxxxxxxx> wrote: > > Introducing the use of asm macros in c-code broke distcc, since it only > sends the preprocessed source file. The solution is to break the > compilation into two separate phases of compilation and assembly, and > between the two concatenate the assembly macros and the compiled (yet > not assembled) source file. Since this is less efficient, this > compilation mode is only used when distcc or icecc are used. > > Note that the assembly stage should also be distributed, if distcc is > configured using "CFLAGS=-DENABLE_REMOTE_ASSEMBLE". > > Reported-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> > Signed-off-by: Nadav Amit <namit@xxxxxxxxxx> Wow, this is so ugly. I realized how much I hated this by now. My question is, how long do we need to carry this? As far as I understood from the long discussion https://lkml.org/lkml/2018/10/7/92 people are trying to deal with it on the compiler side. Is it right? https://gcc.gnu.org/ml/gcc-patches/2018-10/msg01932.html Once it is supported, what would happen on the kernel side? > --- > Makefile | 4 +++- > arch/x86/Makefile | 7 +++++-- > scripts/Makefile.build | 30 ++++++++++++++++++++++++++++-- > 3 files changed, 36 insertions(+), 5 deletions(-) > > diff --git a/Makefile b/Makefile > index 9fce8b91c15f..c07349fc38c7 100644 > --- a/Makefile > +++ b/Makefile > @@ -743,7 +743,9 @@ KBUILD_CFLAGS += $(call cc-option, -gsplit-dwarf, -g) > else > KBUILD_CFLAGS += -g > endif > -KBUILD_AFLAGS += -Wa,-gdwarf-2 > +AFLAGS_DEBUG_INFO = -Wa,-gdwarf-2 > +export AFLAGS_DEBUG_INFO > +KBUILD_AFLAGS += $(AFLAGS_DEBUG_INFO) > endif > ifdef CONFIG_DEBUG_INFO_DWARF4 > KBUILD_CFLAGS += $(call cc-option, -gdwarf-4,) > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index f5d7f4134524..b5953cbcc9c8 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -235,10 +235,13 @@ archscripts: scripts_basic > archheaders: > $(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all > > +ASM_MACRO_FILE = arch/x86/kernel/macros.s > +export ASM_MACRO_FILE > + > archmacros: > - $(Q)$(MAKE) $(build)=arch/x86/kernel arch/x86/kernel/macros.s > + $(Q)$(MAKE) $(build)=arch/x86/kernel $(ASM_MACRO_FILE) > > -ASM_MACRO_FLAGS = -Wa,arch/x86/kernel/macros.s > +ASM_MACRO_FLAGS = -Wa,$(ASM_MACRO_FILE) > export ASM_MACRO_FLAGS > KBUILD_CFLAGS += $(ASM_MACRO_FLAGS) > > diff --git a/scripts/Makefile.build b/scripts/Makefile.build > index 6a6be9f440cf..b8d26bdf48b0 100644 > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -155,8 +155,34 @@ $(obj)/%.ll: $(src)/%.c FORCE > > quiet_cmd_cc_o_c = CC $(quiet_modtag) $@ > > +# If distcc (or icecc) are used, and when assembly macro files are needed, the > +# compilation stage and the assembly stage needs to be separated. Providing the > +# "IGNORE_DISTCC=y" option disables separate compilation and assembly. > + > +cmd_cc_o_c_direct = $(CC) $(c_flags) -c -o $(1) $< > + > +ifneq ($(if $(IGNORE_DISTCC),,$(shell $(CC) --version 2>&1 | head -n 1 | grep -E 'distcc|ICECC')),) > +a_flags_no_debug = $(filter-out $(AFLAGS_DEBUG_INFO), $(a_flags)) > +c_flags_no_macros = $(filter-out $(ASM_MACRO_FLAGS), $(c_flags)) > + > +cmd_cc_o_c_two_steps = \ > + $(CC) $(c_flags_no_macros) $(DISABLE_LTO) -fverbose-asm -S \ > + -o $(@D)/.$(@F:.o=.s) $<; \ > + cat $(ASM_MACRO_FILE) $(@D)/.$(@F:.o=.s) > \ > + $(@D)/.tmp_$(@F:.o=.s); \ > + $(CC) $(a_flags_no_debug) -c -o $(1) $(@D)/.tmp_$(@F:.o=.s); \ > + rm -f $(@D)/.$(@F:.o=.s) $(@D)/.tmp_$(@F:.o=.s) \ > + > +cmd_cc_o_c_helper = \ > + $(if $(findstring $(ASM_MACRO_FLAGS),$(c_flags)), \ > + $(call cmd_cc_o_c_two_steps, $(1)), \ > + $(call cmd_cc_o_c_direct, $(1))) > +else > +cmd_cc_o_c_helper = $(call cmd_cc_o_c_direct, $(1)) > +endif > + > ifndef CONFIG_MODVERSIONS > -cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< > +cmd_cc_o_c = $(call cmd_cc_o_c_helper,$@) > > else > # When module versioning is enabled the following steps are executed: > @@ -171,7 +197,7 @@ else > # replace the unresolved symbols __crc_exported_symbol with > # the actual value of the checksum generated by genksyms > > -cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $< > +cmd_cc_o_c = $(call cmd_cc_o_c_helper,$(@D)/.tmp_$(@F)) > > cmd_modversions_c = \ > if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \ > -- > 2.17.1 > -- Best Regards Masahiro Yamada
