On Sun, Apr 28, 2024 at 12:32:53AM +0900, Masahiro Yamada wrote: > Currently, Kbuild produces inconsistent results in some cases. > > You can do an interesting experiment using the --shuffle option, which > is supported by GNU Make 4.4 or later. > > Set CONFIG_KVM_INTEL=y and CONFIG_KVM_AMD=m (or vice versa), and repeat > incremental builds w/wo --shuffle=reverse. > > $ make > [ snip ] > CC arch/x86/kvm/kvm-asm-offsets.s > > $ make --shuffle=reverse > [ snip ] > CC [M] arch/x86/kvm/kvm-asm-offsets.s > > $ make > [ snip ] > CC arch/x86/kvm/kvm-asm-offsets.s > > arch/x86/kvm/kvm-asm-offsets.s is rebuilt every time w/wo the [M] marker. > > arch/x86/kvm/kvm-asm-offsets.s is built as built-in when it is built as > a prerequisite of arch/x86/kvm/kvm-intel.o, which is built-in. > > arch/x86/kvm/kvm-asm-offsets.s is built as modular when it is built as > a prerequisite of arch/x86/kvm/kvm-amd.o, which is a module. > > Another odd example is single target builds. > > When CONFIG_LKDTM=m, drivers/misc/lkdtm/rodata.o can be built as > built-in or modular, depending on how it is built. > > $ make drivers/misc/lkdtm/lkdtm.o > [ snip ] > CC [M] drivers/misc/lkdtm/rodata.o > > $ make drivers/misc/lkdtm/rodata.o > [ snip ] > CC drivers/misc/lkdtm/rodata.o > > drivers/misc/lkdtm/rodata.o is built as modular when it is built as a > prerequisite of another, but built as built-in when it is a final > target. > > The same thing happens to drivers/memory/emif-asm-offsets.s when > CONFIG_TI_EMIF_SRAM=m. > > $ make drivers/memory/ti-emif-sram.o > [ snip ] > CC [M] drivers/memory/emif-asm-offsets.s > > $ make drivers/memory/emif-asm-offsets.s > [ snip ] > CC drivers/memory/emif-asm-offsets.s > > This is because the part-of-module=y flag defined for the modules is > inherited by its prerequisites. > > Target-specific variables are likely intended only for local use. > This commit adds 'private' to them. > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > --- uh, thanks for fixing this! (And for the bug documentation, as always!) I have just one question below. > > Makefile | 8 ++++---- > scripts/Makefile.build | 6 +++--- > 2 files changed, 7 insertions(+), 7 deletions(-) > > diff --git a/Makefile b/Makefile > index 62557fabfee5..25dcc7ead330 100644 > --- a/Makefile > +++ b/Makefile [...] > @@ -1500,7 +1500,7 @@ MRPROPER_FILES += include/config include/generated \ > > # clean - Delete most, but leave enough to build external modules > # > -clean: rm-files := $(CLEAN_FILES) > +clean: private rm-files := $(CLEAN_FILES) Did you leave 'clean: rm-files := $(KBUILD_EXTMOD)/...' for oot kmods the way it is (w/o 'private') by intention? Even though I cannot think of a possible problem without the 'private', I think it makes sense to change the line as well. W/ or w/o the 'clean'-update for oot kmods: Reviewed-by: Nicolas Schier <n.schier@xxxxxx> Kind regards, Nicolas
