linux-kernel - [PATCH] initramfs: restore default compression behaviour

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Message-Id: <20200311102217.25170-1-Eugeniy.Paltsev@synopsys.com>
Date:   Wed, 11 Mar 2020 13:22:17 +0300
From:   Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
To:     Masahiro Yamada <masahiroy@...nel.org>,
        linux-kernel@...r.kernel.org
Cc:     linux-snps-arc@...ts.infradead.org,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
Subject: [PATCH] initramfs: restore default compression behaviour

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 build systems doesn't look like good option in this
case as it requires to check against kernel version when setting
compression mode. The reason for this is that kconfig options
describing compression mode was renamed (in same patch series) so
we are not able to simply enable one option for old and new kernels.

Given that I propose to use GZIP as default here instead of NO
compression. It should be used only when available but given that
gzip is enabled by default it looks like good enough choice.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
---
 usr/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/usr/Kconfig b/usr/Kconfig
index bdf5bbd40727..690ef9020819 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -102,6 +102,7 @@ config RD_LZ4

 choice
 	prompt "Built-in initramfs compression mode"
+	default INITRAMFS_COMPRESSION_GZIP if RD_GZIP
 	depends on INITRAMFS_SOURCE != ""
 	help
 	  This option allows you to decide by which algorithm the builtin
-- 
2.21.1