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Message-Id: <20080225214209.a3f79327.sbrokenshire@xestia.co.uk> Date: Mon, 25 Feb 2008 21:42:09 +0000 From: Steve Brokenshire <sbrokenshire@...tia.co.uk> To: linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org Subject: [PATCH] Compress kernel modules on installation. Hi, (I've sent this to the linux-kbuild and linux-kernel lists as this patch modifies the Makefile.modinst file. I also don't subscribe to the linux-kbuild and linux-kernel mailing lists so can I have any replies CC'ed to me please) This patch allows kernel modules to be compressed when 'make modules_install' is run after being copied to the /lib/module/<version>/<...> directory which is useful if you have module-init-tools installed with --enable-zlib. This patch adds an option (MODULE_COMPRESS) to the kernel configuration file (specifically init/Kconfig) so that the kernel modules will compressed if MODULE_COMPRESS is set. When MODULE_COMPRESS is set the output of 'make modules_install' will go as the following: INSTALL drivers/fs/xfs/xfs.ko COMPRESS drivers/fs/xfs/xfs.ko INSTALL drivers/fs/fat/fat.ko COMPRESS drivers/fs/fat/fat.ko ... I've tested my patch on kernel versions 2.6.24.2, 2.6.24-git12, 2.6.23.14 and 2.6.19 and they compile, install and compress into the respective module directories without any errors. I've also tested this with the uvcvideo (linux-uvc) kernel module (from the SVN branch and with kernel versions 2.6.24.2, 2.6.24-git12, 2.6.23.14 and 2.6.19) as that uses Kbuild properly when installing the module and after installing the uvcvideo the module is then compressed. Unfortunately, I couldn't find any other kernel modules which used the Kbuild system for installing their kernel modules. :( I've included include/config/auto.conf in Makefile.modinst so that it can check if MODULE_COMPRESS is set when installing the kernel modules. Unfortunately when I ran mkinitrd (CentOS version) to create the initrd image to go with the kernel, I get errors saying that certain kernel modules don't exist despite the fact they do actually exist. When I pass --allow-missing to mkinitrd, it seems to go fine but when booting up with the system with the new initrd image I get error messages saying that the modules don't exist. A workaround is to compile the modules, don't have MODULE_COMPRESS set in .config, install the modules, run mkinitrd and copy it to /boot, set MODULE_COMPRESS in .config and then install the modules again but compressed. That's about it really. The only showstopper I feel is mkinitrd not working properly with the compressed kernel modules. Thanks, Steve --- Signed-off-by: Steve Brokenshire <sbrokenshire@...tia.co.uk> diff -u -r -up a/init/Kconfig b/init/Kconfig --- a/init/Kconfig 2008-02-02 16:34:29.000000000 +0000 +++ b/init/Kconfig 2008-02-03 09:55:52.000000000 +0000 @@ -725,6 +725,30 @@ config MODULE_FORCE_UNLOAD rmmod). This is mainly for kernel developers and desperate users. If unsure, say N. +config MODULE_COMPRESS + bool "Compress kernel modules on installation" + depends on MODULES + help + This option compresses the kernel modules when 'make + modules_install' is run. + + The modules will be compressed into the gzip (GNU zip) format + and will use less space than an uncompressed kernel module would. + + When a kernel module is installed from outside of the main kernel + source and uses the Kbuild system for installing modules then that + kernel module will also be compressed when it is installed. + + When running mkinitrd you will find that an error message + appears saying that it cannot find a certain kernel module. + As a workaround, unset CONFIG_MODULE_COMPRESS, build the modules + and install them, run mkinitrd and create the initrd image, place + the initrd image in the correct place for booting, set + CONFIG_MODULE_COMPRESS and then install the modules again. + + This options requires the module-init-tools package to be + configured with --enable-zlib. + config MODVERSIONS bool "Module versioning support" depends on MODULES diff -u -r -up a/scripts/Makefile.modinst b/scripts/Makefile.modinst --- a/scripts/Makefile.modinst 2008-02-02 16:34:33.000000000 +0000 +++ b/scripts/Makefile.modinst 2008-02-02 17:21:46.000000000 +0000 @@ -5,6 +5,7 @@ PHONY := __modinst __modinst: +include include/config/auto.conf include scripts/Kbuild.include # @@ -16,8 +17,15 @@ PHONY += $(modules) __modinst: $(modules) @: -quiet_cmd_modules_install = INSTALL $@ - cmd_modules_install = mkdir -p $(2); cp $@ $(2) ; $(mod_strip_cmd) $(2)/$(notdir $@) +quiet_cmd_modules_install = INSTALL $@ + cmd_modules_install = mkdir -p $(2); \ + cp $@ $(2) ; \ + $(mod_strip_cmd) $(2)/$(notdir $@) + +quiet_cmd_modules_compress = COMPRESS $@ + cmd_modules_compress = gzip --best -c $(2)/`basename $@` \ + > $(2)/`basename $@...z; \ + rm $(2)/`basename $@` # Modules built outside the kernel source tree go into extra by default INSTALL_MOD_DIR ?= extra @@ -27,7 +35,8 @@ modinst_dir = $(if $(KBUILD_EXTMOD),$(ex $(modules): $(call cmd,modules_install,$(MODLIB)/$(modinst_dir)) - + $(if $(CONFIG_MODULE_COMPRESS), \ + $(call cmd,modules_compress,$(MODLIB)/$(modinst_dir))) # Declare the contents of the .PHONY variable as phony. We keep that # information in a variable se we can use it in if_changed and friends. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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