On 11/10/2024 9:52 am, Frediano Ziglio wrote: > <snip> > > Signed-off-by: Frediano Ziglio <[email protected]>
The makefile changes here are not the easiest to follow, because there are two related things being done. I experimented, and came up with the following: https://xenbits.xen.org/gitweb/?p=people/andrewcoop/xen.git;a=shortlog;h=refs/heads/fz-32b-v3.1 which splits the obj32 transformation out of the "totally change how we link things" which is the purpose of this patch. The end result is much clearer to follow IMO. I've got some other comments, which I've included in the branch, but are presented here for posterity. > diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile > index ff0f965876..4cf0d7e140 100644 > --- a/xen/arch/x86/boot/Makefile > +++ b/xen/arch/x86/boot/Makefile > @@ -1,15 +1,18 @@ > +obj32 := cmdline.o > +obj32 += reloc.o > + > obj-bin-y += head.o > +obj-bin-y += built_in_32.o > > -head-bin-objs := cmdline.o reloc.o > +obj32 := $(patsubst %.o,%.32.o,$(obj32)) We're already used to writing out foo.init.o, so just have the .32.o in list. This makes patch 3 slightly more obvious, where you're not listing the same .o in two different obj lists. > > -nocov-y += $(head-bin-objs) > -noubsan-y += $(head-bin-objs) > -targets += $(head-bin-objs) > +nocov-y += $(obj32) > +noubsan-y += $(obj32) > +targets += $(obj32) > > -head-bin-objs := $(addprefix $(obj)/,$(head-bin-objs)) > +obj32 := $(addprefix $(obj)/,$(obj32)) > > $(obj)/head.o: AFLAGS-y += -Wa$(comma)-I$(obj) > -$(obj)/head.o: $(head-bin-objs:.o=.bin) The AFLAGS-y was only for the .incbin's, so can go away here too. > > CFLAGS_x86_32 := $(subst -m64,-m32 -march=i686,$(XEN_TREEWIDE_CFLAGS)) > $(call cc-options-add,CFLAGS_x86_32,CC,$(EMBEDDED_EXTRA_CFLAGS)) > @@ -17,17 +20,46 @@ CFLAGS_x86_32 += -Werror -fno-builtin -g0 -msoft-float > -mregparm=3 > CFLAGS_x86_32 += -nostdinc -include $(filter > %/include/xen/config.h,$(XEN_CFLAGS)) > CFLAGS_x86_32 += $(filter -I% -O%,$(XEN_CFLAGS)) -D__XEN__ > > +LD32 := $(LD) $(subst x86_64,i386,$(LDFLAGS_DIRECT)) Because this is :=, it needs to be after ... > + > # override for 32bit binaries > -$(head-bin-objs): CFLAGS_stack_boundary := > -$(head-bin-objs): XEN_CFLAGS := $(CFLAGS_x86_32) -fpic > +$(obj32): CFLAGS_stack_boundary := > +$(obj32): XEN_CFLAGS := $(CFLAGS_x86_32) -fpic > > LDFLAGS_DIRECT-$(call ld-option,--warn-rwx-segments) := > --no-warn-rwx-segments > LDFLAGS_DIRECT += $(LDFLAGS_DIRECT-y) ... this. > > -%.bin: %.lnk > - $(OBJCOPY) -j .text -O binary $< $@ > +$(obj)/%.32.o: $(src)/%.c FORCE > + $(call if_changed_rule,cc_o_c) > + > +$(obj)/build32.final.lds: AFLAGS-y += -DFINAL > +$(obj)/build32.other.lds $(obj)/build32.final.lds: $(src)/build32.lds.S > + $(call if_changed_dep,cpp_lds_S) FORCE needs to be a prerequisite to use $(call if_changed_dep) (Sorry - I missed this one in the branch I pushed.) > + > +orphan-handling-$(call ld-option,--orphan-handling=error) := > --orphan-handling=error > + > +# link all object files together All 32bit objects. It isn't even all objects today (head.o isn't included). > +$(obj)/built_in_32.tmp.o: $(obj32) > + $(LD32) -r -o $@ $(obj32) $^ > + > +$(obj)/built_in_32.%.bin: $(obj)/build32.%.lds $(obj)/built_in_32.tmp.o > +## link bundle with a given layout > + $(LD32) $(orphan-handling-y) -N -T $< -Map $(obj)/built_in_32.$(*F).map > -o $(obj)/built_in_32.$(*F).o $(obj)/built_in_32.tmp.o > +## extract binaries from object > + $(OBJCOPY) -j .text -O binary $(obj)/built_in_32.$(*F).o $@ > + rm -f $(obj)/built_in_32.$(*F).o > > -%.lnk: %.o $(src)/build32.lds > - $(LD) $(subst x86_64,i386,$(LDFLAGS_DIRECT)) -N -T $(filter %.lds,$^) > -o $@ $< > +# generate final object file combining and checking above binaries > +$(obj)/built_in_32.o: $(obj)/built_in_32.other.bin > $(obj)/built_in_32.final.bin > + $(PYTHON) $(srctree)/tools/combine_two_binaries \ > + --script $(obj)/build32.final.lds \ > + --bin1 $(obj)/built_in_32.other.bin --bin2 > $(obj)/built_in_32.final.bin \ > + --map $(obj)/built_in_32.final.map \ > + --exports cmdline_parse_early,reloc \ > + --section-header '.section .init.text, "ax", @progbits' \ > + --output $(obj)/built_in_32.s > + $(CC) -c $(obj)/built_in_32.s -o [email protected] > + rm -f $(obj)/built_in_32.s $@ > + mv [email protected] $@ $(obj)/built_in_32.S: and --output $@ The build system already knows how to turn a .S into a .o. This form removed an opencoded $(CC), and leaves built_in_32.S around as an intermediate to be inspected. ~Andrew
