linux: Do not force GZIP initramfs compression
PATCH 1/1 linux: Do not force GZIP initramfs compression
Initramfs compression does not make much sense for the architectures that support compressed kernel images because in this case the data would be compressed twice. This will eventually result in a bigger kernel image and time overhead when uncompressing it.
The only reason to use compressed initramfs is to reduce memory usage when the kernel prepares rootfs, and both the unpacked filesystem and initramfs.cpio are present in the memory.
Buildroot attempts to force GZIP compression for initramfs, however it doesn't always work because initramfs compression mode depends on RAM disk compression supported by the kernel. Thus, CONFIG_INITRAMFS_COMPRESSION_GZIP depends on CONFIG_RD_GZIP. If CONFIG_RD_GZIP is not set, setting GZIP initramfs compression will have no effect.
Besides, the kernel also supports other compression methods, like BZIP2, LZMA, XZ and LZO. Forcing the good old GZIP does not really make much sense any more.
This removes initramfs compression settings from Buildroot, so that the default value preset in the kernel config is used, which is CONFIG_INITRAMFS_COMPRESSION_NONE.
If initramfs compression is still needed, it can be set in the kernel config (using make linux-menuconfig)
--- fs/initramfs/Config.in | 4 ++-- linux/linux.mk | 4 +--- 2 files changed, 3 insertions(+), 5 deletions(-)
fs/initramfs/Config.in +2 -2
@@ -9,8 +9,8 @@ config BR2_TARGET_ROOTFS_INITRAMFS A rootfs.cpio file will be generated in the images/ directory. This is the archive that will be included in the kernel image. - The rootfs in the kernel will always be gzip'ed, regardless - of how buildroot's cpio archive is configured. + The default rootfs compression set in the kernel configuration + is used, regardless of how buildroot's cpio archive is configured. Note that enabling initramfs together with another filesystem formats doesn't make sense: you would end up having two
linux/linux.mk +1 -3
@@ -169,9 +169,7 @@ define LINUX_CONFIGURE_CMDS $(call KCONFIG_ENABLE_OPT,CONFIG_BLK_DEV_INITRD,$(@D)/.config) $(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_SOURCE,\"$(BINARIES_DIR)/rootfs.cpio\",$(@D)/.config) $(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_ROOT_UID,0,$(@D)/.config) - $(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_ROOT_GID,0,$(@D)/.config) - $(call KCONFIG_DISABLE_OPT,CONFIG_INITRAMFS_COMPRESSION_NONE,$(@D)/.config) - $(call KCONFIG_ENABLE_OPT,CONFIG_INITRAMFS_COMPRESSION_GZIP,$(@D)/.config)) + $(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_ROOT_GID,0,$(@D)/.config)) $(if $(BR2_ROOTFS_DEVICE_CREATION_STATIC),, $(call KCONFIG_ENABLE_OPT,CONFIG_DEVTMPFS,$(@D)/.config) $(call KCONFIG_ENABLE_OPT,CONFIG_DEVTMPFS_MOUNT,$(@D)/.config))
Signature · 1 line
1.7.11.4
PATCH 1/1 linux: Do not force GZIP initramfs compression
Quoted 19 lines · Valentine Barshak
Initramfs compression does not make much sense for the architectures that support compressed kernel images because in this case the data would be compressed twice. This will eventually result in a bigger kernel image and time overhead when uncompressing it.
The only reason to use compressed initramfs is to reduce memory usage when the kernel prepares rootfs, and both the unpacked filesystem and initramfs.cpio are present in the memory.Buildroot attempts to force GZIP compression for initramfs, however it doesn't always work because initramfs compression mode depends on RAM disk compression supported by the kernel. Thus,
CONFIG_INITRAMFS_COMPRESSION_GZIPdepends onCONFIG_RD_GZIP. IfCONFIG_RD_GZIPis not set, setting GZIP initramfs compression will have no effect.Besides, the kernel also supports other compression methods, like BZIP2, LZMA, XZ and LZO. Forcing the good old GZIP does not really make much sense any more.
Quoted 8 lines
This removes initramfs compression settings from Buildroot, so that the default value preset in the kernel config is used, which is
CONFIG_INITRAMFS_COMPRESSION_NONE.If initramfs compression is still needed, it can be set in the kernel config (using make linux-menuconfig)
Signed-off-by Valentine Barshak<[email protected]>
I especially like the extensive commit message!
Regards,
Arnout
Signature · 6 lines
Arnout Vandecappelle arnout at mind be Senior Embedded Software Architect +32-16-286540 Essensium/Mind http://www.mind.be G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle GPG fingerprint: 7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F
PATCH 1/1 linux: Do not force GZIP initramfs compression
Agreed.
2012/10/10 Arnout Vandecappelle <[email protected]>
Quoted 51 lines · Valentine Barshak
Quoted 20 lines
Initramfs compression does not make much sense for the architectures that support compressed kernel images because in this case the data would be compressed twice. This will eventually result in a bigger kernel image and time overhead when uncompressing it.
The only reason to use compressed initramfs is to reduce memory usage when the kernel prepares rootfs, and both the unpacked filesystem and initramfs.cpio are present in the memory.Buildroot attempts to force GZIP compression for initramfs, however it doesn't always work because initramfs compression mode depends on RAM disk compression supported by the kernel. Thus, CONFIG_INITRAMFS_COMPRESSION_**GZIP depends on
CONFIG_RD_GZIP. IfCONFIG_RD_GZIPis not set, setting GZIP initramfs compression will have no effect.Besides, the kernel also supports other compression methods, like BZIP2, LZMA, XZ and LZO. Forcing the good old GZIP does not really make much sense any more.
Quoted 9 lines
This removes initramfs compression settings from Buildroot, so that the default value preset in the kernel config is used, which is CONFIG_INITRAMFS_COMPRESSION_**NONE.
If initramfs compression is still needed, it can be set in the kernel config (using make linux-menuconfig)
Signed-off-by Valentine Barshak<[email protected]>I especially like the extensive commit message!
Regards,
Arnout
--Arnout Vandecappelle arnout at mind be Senior Embedded Software Architect +32-16-286540 Essensium/Mind http://www.mind.be G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven LinkedIn profile: http://www.linkedin.com/in/**arnoutvandecappelle<http://www.linkedin.com/in/arnoutvandecappelle> GPG fingerprint: 7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F______________________________**_________________
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PATCH 1/1 linux: Do not force GZIP initramfs compression
In reply to Valentine BarshakQuoted 1 line
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"Valentine" == Valentine Barshak <[email protected]> writes:
Valentine> Initramfs compression does not make much sense for the architectures Valentine> that support compressed kernel images because in this case the data Valentine> would be compressed twice. This will eventually result in a bigger Valentine> kernel image and time overhead when uncompressing it. Valentine> The only reason to use compressed initramfs is to reduce memory Valentine> usage when the kernel prepares rootfs, and both the unpacked Valentine> filesystem and initramfs.cpio are present in the memory.
Valentine> Buildroot attempts to force GZIP compression for initramfs, Valentine> however it doesn't always work because initramfs compression mode Valentine> depends on RAM disk compression supported by the kernel. Valentine> Thus, CONFIG_INITRAMFS_COMPRESSION_GZIP depends on CONFIG_RD_GZIP. Valentine> If CONFIG_RD_GZIP is not set, setting GZIP initramfs compression Valentine> will have no effect.
Valentine> Besides, the kernel also supports other compression methods, Valentine> like BZIP2, LZMA, XZ and LZO. Forcing the good old GZIP does not Valentine> really make much sense any more.
Valentine> This removes initramfs compression settings from Buildroot, Valentine> so that the default value preset in the kernel config is used, Valentine> which is CONFIG_INITRAMFS_COMPRESSION_NONE.
Valentine> If initramfs compression is still needed, it can be set Valentine> in the kernel config (using make linux-menuconfig)
Sorry, this somehow seems to have fallen through the cracks - Committed, thanks.
Signature · 1 line
Bye, Peter Korsgaard