On Mon, Jul 23, 2007 at 12:26:13AM -0700, Roland McGrath wrote:
> > Should be doable without to much pain.
> > Alan can you please share with us exactly why this is better and what we may
> > run into of problems doing so.
> > A sample script would be nice too....
>
> This about does it. Polish left as an exercise to the reader.
> ld does "interesting" things if the linker scripts are inside --start-group.
Thanks - will take a look during the week.
I will most likely rename built-in.o to something else and reflect this
in Makefile.build. Just to make it clear this is now a linker script file.
But I would still like to hear from Alan what the benefits are.
I foresee that with this change it will take longer to build a kernel
after a single change but that a full kernel build is shorter.
And thats the wrong way to optimze...
Sam
>
> diff --git a/Makefile b/Makefile
> index cd47845..0000000 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -613,12 +613,15 @@ vmlinux-all := $(vmlinux-init) $(vmlinu
> vmlinux-lds := arch/$(ARCH)/kernel/vmlinux.lds
> export KBUILD_VMLINUX_OBJS := $(vmlinux-all)
>
> +vmlinux-link-main = $(filter-out %.a,$(vmlinux-main)) \
> + --start-group $(filter %.a,$(vmlinux-main)) --end-group
> +
> # Rule to link vmlinux - also used during CONFIG_KALLSYMS
> # May be overridden by arch/$(ARCH)/Makefile
> quiet_cmd_vmlinux__ ?= LD $@
> cmd_vmlinux__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \
> -T $(vmlinux-lds) $(vmlinux-init) \
> - --start-group $(vmlinux-main) --end-group \
> + $(vmlinux-link-main) \
> $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o FORCE ,$^)
>
> # Generate new vmlinux version
> @@ -747,7 +750,7 @@ endif # ifdef CONFIG_KALLSYMS
> # relevant sections renamed as per the linker script.
> quiet_cmd_vmlinux-modpost = LD $@
> cmd_vmlinux-modpost = $(LD) $(LDFLAGS) -r -o $@ \
> - $(vmlinux-init) --start-group $(vmlinux-main) --end-group \
> + $(vmlinux-init) $(vmlinux-link-main) \
> $(filter-out $(vmlinux-init) $(vmlinux-main) $(vmlinux-lds) FORCE ,$^)
> define rule_vmlinux-modpost
> :
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 3f7b451..0000000 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -274,11 +274,11 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ;
> # Rule to compile a set of .o files into one .o file
> #
> ifdef builtin-target
> -quiet_cmd_link_o_target = LD $@
> +quiet_cmd_link_o_target = LDS $@
> # If the list of objects to link is empty, just create an empty built-in.o
> -cmd_link_o_target = $(if $(strip $(obj-y)),\
> - $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^),\
> - rm -f $@; $(AR) rcs $@)
> +cmd_link_o_target = echo > [email protected] $(if $(strip $(obj-y)),\
> + 'INPUT($(filter $(obj-y), $^))') && \
> + mv -f [email protected] $@
>
> $(builtin-target): $(obj-y) FORCE
> $(call if_changed,link_o_target)
> @@ -311,11 +311,11 @@ $(filter $(addprefix $(obj)/, \
> $($(subst $(obj)/,,$(@:.o=-objs))) \
> $($(subst $(obj)/,,$(@:.o=-y)))), $^)
>
> -quiet_cmd_link_multi-y = LD $@
> -cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps)
> +quiet_cmd_link_multi-y = LDS $@
> +cmd_link_multi-y = echo > [email protected] 'INPUT($(link_multi_deps))' && mv -f [email protected] $@
>
> quiet_cmd_link_multi-m = LD [M] $@
> -cmd_link_multi-m = $(LD) $(ld_flags) $(LDFLAGS_MODULE) -o $@ $(link_multi_deps)
> +cmd_link_multi-m = $(cmd_link_multi-y)
This signel change looks wrong. We do not want to generate a linker
script for modules.
Sam
-
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