Re: [PATCH v4 3/3] kbuild: generate autoksyms.h early

[Matthias Maennich]

On Wed, Feb 12, 2020 at 08:21:40PM +0000, Quentin Perret wrote:
> When doing a cold build, autoksyms.h starts empty, and is updated late
> in the build process to have visibility over the symbols used by in-tree
> drivers. But since the symbol whitelist is known upfront, it can be used
> to pre-populate autoksyms.h and maximize the amount of code that can be
> compiled to its final state in a single pass, hence reducing build time.
>
> Do this by using gen_autoksyms.sh to initialize autoksyms.h instead of
> creating an empty file.
>
> Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>

Reviewed-by: Matthias Maennich <maennich@xxxxxxxxxx>
Tested-by: Matthias Maennich <maennich@xxxxxxxxxx>

Cheers,
Matthias

> ---
> Makefile                 | 7 +++++--
> scripts/gen_autoksyms.sh | 3 ++-
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 84b71845c43f..17b7e7f441bd 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1062,9 +1062,12 @@ endif
>
> autoksyms_h := $(if $(CONFIG_TRIM_UNUSED_KSYMS), include/generated/autoksyms.h)
>
> +quiet_cmd_autoksyms_h = GEN     $@
> +      cmd_autoksyms_h = mkdir -p $(dir $@); $(CONFIG_SHELL) \
> +			$(srctree)/scripts/gen_autoksyms.sh $@
> +
> $(autoksyms_h):
> -	$(Q)mkdir -p $(dir $@)
> -	$(Q)touch $@
> +	$(call cmd,autoksyms_h)
>
> ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
>
> diff --git a/scripts/gen_autoksyms.sh b/scripts/gen_autoksyms.sh
> index 2cea433616a8..f52b93ad122c 100755
> --- a/scripts/gen_autoksyms.sh
> +++ b/scripts/gen_autoksyms.sh
> @@ -32,7 +32,8 @@ cat > "$output_file" << EOT
>
> EOT
>
> -sed 's/ko$/mod/' modules.order |
> +[ -f modules.order ] && modlist=modules.order || modlist=/dev/null
> +sed 's/ko$/mod/' $modlist |
> xargs -n1 sed -n -e '2{s/ /\n/g;/^$/!p;}' -- |
> cat - "$ksym_wl" |
> sort -u |
> --
> 2.25.0.225.g125e21ebc7-goog