Dirk Gouders <dirk@xxxxxxxxxxx> writes: > Dirk Gouders <dirk@xxxxxxxxxxx> writes: > >> Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> writes: >> >>> syncconfig updates the .config only when sym_change_count > 0, i.e. >>> any change in config symbols has been detected. >>> >>> Not only symbols but also comments are contained in the .config file. >>> If only comments are updated, they are not fed back to the .config, >>> then the stale comments are left-over. Of course, this is just a >>> matter of comments, but why not fix it. >> >> Hello Masahiro, >> >> I am currently looking at and testing this series. >> >> First: For this patch I would suggest to also edit the syncconfig >> section of "conf --help". >> >> Further, on a slow laptop, I was suspecting, this patch to cause full >> rebuilds of everything, each time I ran "make syncconfig" followed by >> "make" but could not verify this on another machine, so perhaps I am >> just (for testing purposes) removing the wrong files (modules.builtin >> for example) -- I am still testing. >> >> But, what irritates me with testing is that (also without your >> patches) two consecutive "make" produce different output, one of them >> always shows a warning and this is reproducable. I just want to make >> sure there is no other problem that influences my testing: >> >> $ make >> CALL scripts/checksyscalls.sh >> DESCEND objtool >> CHK include/generated/compile.h >> DATAREL arch/x86/boot/compressed/vmlinux >> Kernel: arch/x86/boot/bzImage is ready (#15) >> Building modules, stage 2. >> MODPOST 211 modules >> >> $ make >> CALL scripts/checksyscalls.sh >> DESCEND objtool >> CHK include/generated/compile.h >> LD arch/x86/boot/compressed/vmlinux >> ld: arch/x86/boot/compressed/head_64.o: warning: relocation in read-only section `.head.text' >> ld: warning: creating a DT_TEXTREL in object. >> ZOFFSET arch/x86/boot/zoffset.h >> AS arch/x86/boot/header.o >> LD arch/x86/boot/setup.elf >> OBJCOPY arch/x86/boot/setup.bin >> OBJCOPY arch/x86/boot/vmlinux.bin >> BUILD arch/x86/boot/bzImage >> Setup is 15580 bytes (padded to 15872 bytes). >> System is 8069 kB >> CRC e01d75ec >> Kernel: arch/x86/boot/bzImage is ready (#15) >> Building modules, stage 2. >> MODPOST 211 modules > > I spent some more time with the behaviour described above and bisected > to the commit after that two consecutive invocations of "make" (on an > already compiled tree) seem to do different things. That commit is > 98f78525371b55cc (x86/boot: Refuse to build with data relocations), so I > put Kees and Ingo on CC. > > I did the bisecting on another system, so I'll provide the output of two > consecutive "make" on an already compiled tree on that machine: > > $ make > CALL scripts/checksyscalls.sh > DESCEND objtool > CHK include/generated/compile.h > DATAREL arch/x86/boot/compressed/vmlinux > Kernel: arch/x86/boot/bzImage is ready (#48) > Building modules, stage 2. > MODPOST 165 modules > > $ make > CALL scripts/checksyscalls.sh > DESCEND objtool > CHK include/generated/compile.h > LD arch/x86/boot/compressed/vmlinux > ZOFFSET arch/x86/boot/zoffset.h > AS arch/x86/boot/header.o > LD arch/x86/boot/setup.elf > OBJCOPY arch/x86/boot/setup.bin > OBJCOPY arch/x86/boot/vmlinux.bin > BUILD arch/x86/boot/bzImage > Setup is 15644 bytes (padded to 15872 bytes). > System is 6663 kB > CRC 3eb90f40 > Kernel: arch/x86/boot/bzImage is ready (#48) > Building modules, stage 2. > MODPOST 165 modules > > If I comment out $(call if_changed,check_data_rel) in > arch/x86/boot/compressed/Makefile, two consecutive "make" produce > identical output i.e. seem to not do different things: > > $ make > CALL scripts/checksyscalls.sh > DESCEND objtool > CHK include/generated/compile.h > Kernel: arch/x86/boot/bzImage is ready (#49) > Building modules, stage 2. > MODPOST 165 modules > > $ make > CALL scripts/checksyscalls.sh > DESCEND objtool > CHK include/generated/compile.h > Kernel: arch/x86/boot/bzImage is ready (#49) > Building modules, stage 2. > MODPOST 165 modules > > So, I guess this different behaviour of two consecutive "make" is not > intentional but I am failing to understand why it happens. I think, I solved the puzzle and perhaps, that saves others some time: The problem is that "if_changed" was not designed for multiple use inside a recipe and in the case of compressed/vmlinux, the 2-fold use created a kind of flip-flop for situations when nothing has to be done to build the target. Because each of the two users of "if_changed" stores it's footprint in .vmlinux.cmd but that file then isn't re-read, one of the two "if_changed" calculates that nothing has to be done wheras the other one recognizes a change in the commandline, because it sees the command-line for the other part of the reciepe. In the next make, the roles flip, because the previously satisfied "if_changed" now sees the command-line of the other one. And so on... I am not a Kbuild expert but the attached patch fixes that problem by introducing "if_changed_multi" that accepts two commands -- one whose commandline should be checked and a second one that should be executed. Dirk
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index fa42f895fdde..f39822fca994 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -107,8 +107,8 @@ define cmd_check_data_rel endef $(obj)/vmlinux: $(vmlinux-objs-y) FORCE - $(call if_changed,check_data_rel) - $(call if_changed,ld) + $(call if_changed_multi,ld,check_data_rel) + $(call if_changed_multi,ld,ld) OBJCOPYFLAGS_vmlinux.bin := -R .comment -S $(obj)/vmlinux.bin: vmlinux FORCE diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index b2d14f1136e8..3bf419319e09 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -265,6 +265,23 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)), \ $(echo-cmd) $(cmd_$(1)); \ printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:) +# echo command for command stored in $2 +# Short version is used, if $(quiet) equals `quiet_', otherwise full one. +echo-cmd2 = $(if $($(quiet)cmd_$(2)),\ + echo ' $(call escsq,$($(quiet)cmd_$(2)))$(echo-why)';) + +# Execute command arg2 if commandline for command arg1 or prerequisite(s) are +# updated. +# +# This is safe for multiple use inside a recipe; arg1 and arg2 may be +# identical. +if_changed_multi = $(if $(strip $(any-prereq) $(arg-check)), \ + @set -e; \ + $(echo-cmd2) : ; \ + $(cmd_$(2)); \ + printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:) + + # Execute the command and also postprocess generated .d dependencies file. if_changed_dep = $(if $(strip $(any-prereq) $(arg-check) ), \ @set -e; \
