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SubjectRe: kbuild: Simplify vmlinux generation
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Sam Ravnborg <sam@ravnborg.org> said:

[...]

Some comments interspersed.

Signed off by: Horst H. von Brand <vonbrand@inf.utfsm.cl>

(Not too much intellect in here, and no property, but...)

> diff -Nru a/Makefile b/Makefile
> --- a/Makefile 2004-09-05 22:06:47 +02:00
> +++ b/Makefile 2004-09-05 22:06:47 +02:00
> @@ -545,67 +545,91 @@
>
> # Build vmlinux
> # ---------------------------------------------------------------------------
> +# vmlinux is build from the objects seleted by $(vmlinux-init) and

selected

> +# $(vmlinux-main). Most are built-in.o files from top-level directories
> +# in the kernel tree, others are specified in arch/$(ARCH)Makefile.
> +# Ordering when linking is important, and $(vmlinux-init) must be first.
> +#
> +# vmlinux
> +# ^
> +# |
> +# +-< $(vmlinux-init)
> +# | +--< init/version.o + more
> +# |
> +# +-< built-in.o
> +# | +--< $(vmlinux-main)
> +# | +--< driver/built-in.o mm/built-in.o + more
> +# |
> +# +-< kallsyms.o (see description in CONFIG_KALLSYMS section)
> +#
> +# vmlinux version cannot be updated during normal descending-into-subdirs

The vmlinux version? Or some file?

> +# phase since we do not yet know if we need to update vmlinux.
> +# Therefore this step is delayed until just before final link of vmlinux -
> +# except in kallsyms case where it is done just before adding the

in the kallsyms case

> +# symbols to the kernel.
> +#
> +# System.map is generated to document addresses of all kernel symbols
>
> -# This is a bit tricky: If we need to relink vmlinux, we want
> -# the version number incremented, which means recompile init/version.o
> -# and relink init/init.o. However, we cannot do this during the
> -# normal descending-into-subdirs phase, since at that time
> -# we cannot yet know if we will need to relink vmlinux.
> -# So we descend into init/ inside the rule for vmlinux again.
> -vmlinux-objs := $(head-y) $(init-y) $(core-y) $(libs-y) $(drivers-y) $(net-y)
> -
> -quiet_cmd_vmlinux__ = LD $@
> -define cmd_vmlinux__
> - $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) $(head-y) $(init-y) \
> - --start-group \
> - $(core-y) \
> - $(libs-y) \
> - $(drivers-y) \
> - $(net-y) \
> - --end-group \
> - $(filter .tmp_kallsyms%,$^) \
> - -o $@
> -endef
> +vmlinux-init := $(head-y) $(init-y)
> +vmlinux-main := $(core-y) $(libs-y) $(drivers-y) $(net-y)
> +vmlinux-all := $(vmlinux-init) built-in.o
> +vmlinux-lds := arch/$(ARCH)/kernel/vmlinux.lds
> +
> +# 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) \
> + -T $(filter-out FORCE, $^) -o $@
> +
> +# Generate new vmlinux version
> +quiet_cmd_vmlinux_version = GEN .version
> + cmd_vmlinux_version = set -e; \
> + . $(srctree)/scripts/mkversion > .tmp_version; \
> + mv -f .tmp_version .version; \
> + $(MAKE) $(build)=init
> +
> +# Generate System.map
> +quiet_cmd_sysmap = SYSMAP
> + cmd_sysmap = $(CONFIG_SHELL) $(srctree)/scripts/mksysmap
>
> -# set -e makes the rule exit immediately on error
> +# Link of vmlinux
> +# If CONFIG_KALLSYMS is set .version is already updated
> +# Generate System.map and verify that the content is consistent
>
> define rule_vmlinux__
> - +set -e; \
> - $(if $(filter .tmp_kallsyms%,$^),, \
> - echo ' GEN .version'; \
> - . $(srctree)/scripts/mkversion > .tmp_version; \
> - mv -f .tmp_version .version; \
> - $(MAKE) $(build)=init; \
> - ) \
> - $(if $($(quiet)cmd_vmlinux__), \
> - echo ' $($(quiet)cmd_vmlinux__)' &&) \
> - $(cmd_vmlinux__); \
> - echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
> + $(if $(CONFIG_KALLSYMS),,$(call cmd,vmlinux_version))
> +
> + $(call cmd,vmlinux__)
> + $(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd
> +
> + $(Q)$(if $($(quiet)cmd_sysmap), \
> + echo ' $($(quiet)cmd_sysmap) System.map' &&) \
> + $(cmd_sysmap) $@ System.map; \
> + if [ $$? -ne 0 ]; then \
> + rm -f $@; \
> + /bin/false; \
> + fi;
> + $(verify_kallsyms)
> endef
>
> -quiet_cmd_sysmap = SYSMAP
> - cmd_sysmap = $(CONFIG_SHELL) $(srctree)/scripts/mksysmap
> -
> -LDFLAGS_vmlinux += -T arch/$(ARCH)/kernel/vmlinux.lds
> -
> -# Generate section listing all symbols and add it into vmlinux
> -# It's a three stage process:
> -# o .tmp_vmlinux1 has all symbols and sections, but __kallsyms is
> -# empty
> -# Running kallsyms on that gives us .tmp_kallsyms1.o with
> -# the right size
> -# o .tmp_vmlinux2 now has a __kallsyms section of the right size,
> -# but due to the added section, some addresses have shifted
> -# From here, we generate a correct .tmp_kallsyms2.o
> -# o The correct .tmp_kallsyms2.o is linked into the final vmlinux.
> -# o Verify that the System.map from vmlinux matches the map from
> -# .tmp_vmlinux2, just in case we did not generate kallsyms correctly.
> -# o If CONFIG_KALLSYMS_EXTRA_PASS is set, do an extra pass using
> -# .tmp_vmlinux3 and .tmp_kallsyms3.o. This is only meant as a
> -# temporary bypass to allow the kernel to be built while the
> -# maintainers work out what went wrong with kallsyms.
>
> ifdef CONFIG_KALLSYMS
> +# Generate section listing all symbols and add it into vmlinux $(kallsyms.o)
> +# It's a three stage process:
> +# o .tmp_vmlinux1 has all symbols and sections, but __kallsyms is
> +# empty
> +# Running kallsyms on that gives us .tmp_kallsyms1.o with
> +# the right size - vmlinux version updated during this step

is updated

> +# o .tmp_vmlinux2 now has a __kallsyms section of the right size,
> +# but due to the added section, some addresses have shifted.
> +# From here, we generate a correct .tmp_kallsyms2.o
> +# o The correct .tmp_kallsyms2.o is linked into the final vmlinux.
> +# o Verify that the System.map from vmlinux matches the map from
> +# .tmp_vmlinux2, just in case we did not generate kallsyms correctly.
> +# o If CONFIG_KALLSYMS_EXTRA_PASS is set, do an extra pass using
> +# .tmp_vmlinux3 and .tmp_kallsyms3.o. This is only meant as a
> +# temporary bypass to allow the kernel to be built while the
> +# maintainers work out what went wrong with kallsyms.
>
> ifdef CONFIG_KALLSYMS_EXTRA_PASS
> last_kallsyms := 3
> @@ -615,16 +639,28 @@
>
> kallsyms.o := .tmp_kallsyms$(last_kallsyms).o
>
> -define rule_verify_kallsyms
> +define verify_kallsyms

Why delete "rule_" here? Down you create a new rule with "rule_"

[No further comments, rest snipped]
--
Dr. Horst H. von Brand User #22616 counter.li.org
Departamento de Informatica Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria +56 32 654239
Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513
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