Dne 9.6.2014 18:23, Sam Ravnborg napsal(a):
> From b92cb72f08908a718da05318975545e988bfdaf9 Mon Sep 17 00:00:00 2001
> From: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Date: Mon, 9 Jun 2014 18:03:22 +0200
> Subject: [PATCH] kbuild: move cc_c_o logic to a shell script
>
> The amount of makefile magic required when building a
> .o file from a .c file had grown far too much.
> Move all the logic to a shell script where it is much
> easier to follow the sequence and thus easier to debug/enhance.
That's a nice cleanup! Some review below, but I'll have to do one more pass.
> This transition has following impact on the current functionality:
> - We no longer rebuild the kernel if the source for recordmount is changed
> The source filehas not changed for a couple of years
Yeah, that should not be an issue.
> - A shortcut to build symtypes files is lost. It was never
> supported by the top-level Makefile anyway
There is a rule for that:
%.symtypes: %.c prepare scripts FORCE
$(Q)$(MAKE) $(build)=$(build-dir) $(target-dir)$(notdir $@)
But it could be added to the script, e.g. if $outfile ends in .symtypes,
do just the genksyms run.
> diff --git a/scripts/kcc.sh b/scripts/kcc.sh
> new file mode 100644
> index 0000000..2b0bad6
> --- /dev/null
> +++ b/scripts/kcc.sh
> @@ -0,0 +1,187 @@
> +#!/bin/sh
> +# kernel wrapper for cc
> +# In the simple case we just call cc with the supplied arguments.
> +# But we may check the source with sparse before we call cc.
> +# And we may postprocess the source or the .o file to support
> +# module versioning and function tracing.
> +
> +# Error out on error
> +set -e
> +
> +# Print command and execute
> +# ${quiet} determine which command to print (if any)
> +run()
> +{
> + case "${quiet}" in
> + "silent_")
> + shift
> + ;;
> + "quiet_")
> + printf " %s \n" "$1 ${why}"
> + shift
> + ;;
> + *)
> + shift
> + echo "$*"
While there is no -n or -e option to gcc, I'd use printf just to be on
the safe side:
printf '%s\n' "$*"
> + esac
> +
> + # Run the command
> + $*
> +}
> +
> +# Calculate symbol versions on the preprocessed source
> +# using genksyms and postprocess the output in a way
> +# that it is usable as a linker script.
> +# Then generate the .o file with the __crc_exported_symbol replaced.
> +gen_sym_types()
> +{
> + if [ "${KBUILD_SYMTYPES}" = "y" ]; then
> + dump_types="-T $1.symtypes"
> + fi
> +
> + if [ "${CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX}" = "y" ]; then
> + mod_prefix="-s _"
> + fi
> +
> + if [ "${KBUILD_PRESERVE}" != "" ]; then
> + preserve="-p";
> + if [ -f $1.symref ]; then
> + reference="-r $1.symref"
> + fi
> + fi
The -r <file>.symref should not depend on KBUILD_PRESERVE
> +
> + out=$1.ver
> + shift
> +
> + ${CPP} -D__GENKSYMS__ $* ${infile} | \
> + ${GENKSYMS} ${dump_types} ${mod_prefix} ${preserve} ${reference} > ${out}
> +
> + # Generate <file>.o from .tmp_<file>.o using the linker to
> + # replace the unresolved symbols __crc_exported_symbol with
> + # the actual value of the checksum generated by genksyms
> + ${LD} ${LDFLAGS} -r -o ${outfile} ${tmpfile}.o -T ${out}
> + rm -f ${tmpfile}.o ${out}
> +}
> +
> +# Create __mcount_loc section with pointers to all calls to mcount
> +record_mcount()
> +{
> + # Due to recursion, we must skip empty.o.
> + # The empty.o file is created in the make process in order to determine
> + # the target endianness and word size. It is made before all other C
> + # files, including recordmcount.
> +
> + if [ "$(basename ${outfile})" = "empty.o" ]; then
> + return
> + fi
> +
> + if [ "${BUILD_C_RECORDMCOUNT}" != "" ]; then
> + if [ "${RECORDMCOUNT_WARN}" != "" ]; then
In the Makefile, there was a check for RECORDMCOUNT_WARN coming from the
make command line, but that's not a big deal. Just document it in the
changelog.
> +# Do we have to run record_mcount?
> +if [ "${CONFIG_FTRACE_MCOUNT_RECORD}" != "" ]; then
> + if [ $(echo $* | grep -c -e "-pg") -gt 0 ]; then
case " $* " in
" -pg ")
record_mcount
esac
This has the advantage over the Makefile version that it checks a whole
word "-pg". Also, it saves some forking.
Michal
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