[PATCH v2] initramfs: restore default compression behavior

[PATCH v2] initramfs: restore default compression behavior

[Eugeniy Paltsev]

Even though INITRAMFS_SOURCE kconfig option isn't set in most of
defconfigs it is used (set) extensively by various build systems.
Commit f26661e12765 ("initramfs: make initramfs compression choice
non-optional") has changed default compression mode. Previously we
compress initramfs using available compression algorithm. Now
we don't use any compression at all by default.
It significantly increases the image size in case of build system
chooses embedded initramfs. Initially I faced with this issue while
using buildroot.

As of today it's not possible to set preferred compression mode
in target defconfig as this option depends on INITRAMFS_SOURCE
being set. Modification of all build systems either doesn't look
like good option.

Let's instead rewrite initramfs compression mode choices list
the way that "INITRAMFS_COMPRESSION_NONE" will be the last option
in the list. In that case it will be chosen only if all other
options (which implements any compression) are not available.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
 usr/Kconfig | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/usr/Kconfig b/usr/Kconfig
index bdf5bbd40727..96afb03b65f9 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -124,17 +124,6 @@ choice
 
 	  If in doubt, select 'None'
 
-config INITRAMFS_COMPRESSION_NONE
-	bool "None"
-	help
-	  Do not compress the built-in initramfs at all. This may sound wasteful
-	  in space, but, you should be aware that the built-in initramfs will be
-	  compressed at a later stage anyways along with the rest of the kernel,
-	  on those architectures that support this. However, not compressing the
-	  initramfs may lead to slightly higher memory consumption during a
-	  short time at boot, while both the cpio image and the unpacked
-	  filesystem image will be present in memory simultaneously
-
 config INITRAMFS_COMPRESSION_GZIP
 	bool "Gzip"
 	depends on RD_GZIP
@@ -207,4 +196,15 @@ config INITRAMFS_COMPRESSION_LZ4
 	  If you choose this, keep in mind that most distros don't provide lz4
 	  by default which could cause a build failure.
 
+config INITRAMFS_COMPRESSION_NONE
+	bool "None"
+	help
+	  Do not compress the built-in initramfs at all. This may sound wasteful
+	  in space, but, you should be aware that the built-in initramfs will be
+	  compressed at a later stage anyways along with the rest of the kernel,
+	  on those architectures that support this. However, not compressing the
+	  initramfs may lead to slightly higher memory consumption during a
+	  short time at boot, while both the cpio image and the unpacked
+	  filesystem image will be present in memory simultaneously
+
 endchoice
-- 
2.21.1


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Re: [PATCH v2] initramfs: restore default compression behavior

[Masahiro Yamada]

On Mon, Mar 16, 2020 at 8:25 PM Eugeniy Paltsev
<Eugeniy.Paltsev@synopsys.com> wrote:
>
> Even though INITRAMFS_SOURCE kconfig option isn't set in most of
> defconfigs it is used (set) extensively by various build systems.
> Commit f26661e12765 ("initramfs: make initramfs compression choice
> non-optional") has changed default compression mode. Previously we
> compress initramfs using available compression algorithm. Now
> we don't use any compression at all by default.
> It significantly increases the image size in case of build system
> chooses embedded initramfs. Initially I faced with this issue while
> using buildroot.
>
> As of today it's not possible to set preferred compression mode
> in target defconfig as this option depends on INITRAMFS_SOURCE
> being set. Modification of all build systems either doesn't look
> like good option.
>
> Let's instead rewrite initramfs compression mode choices list
> the way that "INITRAMFS_COMPRESSION_NONE" will be the last option
> in the list. In that case it will be chosen only if all other
> options (which implements any compression) are not available.
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>


Applied to linux-kbuild.
Thanks.



> ---
>  usr/Kconfig | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/usr/Kconfig b/usr/Kconfig
> index bdf5bbd40727..96afb03b65f9 100644
> --- a/usr/Kconfig
> +++ b/usr/Kconfig
> @@ -124,17 +124,6 @@ choice
>
>           If in doubt, select 'None'
>
> -config INITRAMFS_COMPRESSION_NONE
> -       bool "None"
> -       help
> -         Do not compress the built-in initramfs at all. This may sound wasteful
> -         in space, but, you should be aware that the built-in initramfs will be
> -         compressed at a later stage anyways along with the rest of the kernel,
> -         on those architectures that support this. However, not compressing the
> -         initramfs may lead to slightly higher memory consumption during a
> -         short time at boot, while both the cpio image and the unpacked
> -         filesystem image will be present in memory simultaneously
> -
>  config INITRAMFS_COMPRESSION_GZIP
>         bool "Gzip"
>         depends on RD_GZIP
> @@ -207,4 +196,15 @@ config INITRAMFS_COMPRESSION_LZ4
>           If you choose this, keep in mind that most distros don't provide lz4
>           by default which could cause a build failure.
>
> +config INITRAMFS_COMPRESSION_NONE
> +       bool "None"
> +       help
> +         Do not compress the built-in initramfs at all. This may sound wasteful
> +         in space, but, you should be aware that the built-in initramfs will be
> +         compressed at a later stage anyways along with the rest of the kernel,
> +         on those architectures that support this. However, not compressing the
> +         initramfs may lead to slightly higher memory consumption during a
> +         short time at boot, while both the cpio image and the unpacked
> +         filesystem image will be present in memory simultaneously
> +
>  endchoice
> --
> 2.21.1
>


-- 
Best Regards
Masahiro Yamada

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