Re: [PATCH 9/9] kbuild: remove CONFIG_MODULE_COMPRESS

Nick Desaulniers
2021-03-31T18:02:15Z

On Wed, Mar 31, 2021 at 6:39 AM Masahiro Yamada <masahiroy@kernel.org> wrote:

Should the online be Kconfig rather than Kbuild, for a commit that
only changes Kconfigs?

>
> CONFIG_MODULE_COMPRESS is only used to activate the choice for module
> compression algorithm. It will be simpler to make the choice visible
> all the time by adding CONFIG_MODULE_COMPRESS_NONE to allow the user to
> disable module compression.
>
> This is more consistent with the "Kernel compression mode" and "Built-in
> initramfs compression mode" choices.
>
> CONFIG_KERNEL_UNCOMPRESSED and CONFIG_INITRAMFS_COMPRESSION_NONE are
> available to choose to not compress the kernel, initrd, respectively.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> init/Kconfig | 45 ++++++++++++++++++++++++++-------------------
> 1 file changed, 26 insertions(+), 19 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 019c1874e609..3ca1ffd219c4 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -2225,40 +2225,47 @@ config MODULE_SIG_HASH
> default "sha384" if MODULE_SIG_SHA384
> default "sha512" if MODULE_SIG_SHA512
>
> -config MODULE_COMPRESS

The top level Makefile has comments and code that refer to this choice
which is now removed. I think you'll want to fix that up in this
change as well? Ah, patch 7 in the series does that:
https://lore.kernel.org/linux-kbuild/20210331133811.3221540-7-masahiroy@kernel.org/

Ok then this LGTM.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> - bool "Compress modules on installation"
> +choice
> + prompt "Module compression mode"
> help
> + This option allows you to choose the algorithm which will be used to
> + compress modules when 'make modules_install' is run. (or, you can
> + choose to not compress modules at all.)
>
> - Compresses kernel modules when 'make modules_install' is run; gzip or
> - xz depending on "Compression algorithm" below.
> + External modules will also be compressed in the same way during the
> + installation.
>
> - module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
> + For modules inside an initrd or initramfs, it's more efficient to
> + compress the whole initrd or initramfs instead.
>
> - Out-of-tree kernel modules installed using Kbuild will also be
> - compressed upon installation.
> + This is fully compatible with signed modules.
>
> - Note: for modules inside an initrd or initramfs, it's more efficient
> - to compress the whole initrd or initramfs instead.
> + Please note that the tool used to load modules needs to support the
> + corresponding algorithm. module-init-tools MAY support gzip, and kmod
> + MAY support gzip and xz.
>
> - Note: This is fully compatible with signed modules.
> + Your build system needs to provide the appropriate compression tool
> + to compress the modules.
>
> - If in doubt, say N.
> + If in doubt, select 'None'.
>
> -choice
> - prompt "Compression algorithm"
> - depends on MODULE_COMPRESS
> - default MODULE_COMPRESS_GZIP
> +config MODULE_COMPRESS_NONE
> + bool "None"
> help
> - This determines which sort of compression will be used during
> - 'make modules_install'.
> -
> - GZIP (default) and XZ are supported.
> + Do not compress modules. The installed modules are suffixed
> + with .ko.
>
> config MODULE_COMPRESS_GZIP
> bool "GZIP"
> + help
> + Compress modules with XZ. The installed modules are suffixed
> + with .ko.gz.
>
> config MODULE_COMPRESS_XZ
> bool "XZ"
> + help
> + Compress modules with XZ. The installed modules are suffixed
> + with .ko.xz.
>
> endchoice
>
> --
> 2.27.0
>

--
Thanks,
~Nick Desaulniers