From: Daniel Thompson <daniel.thompson@xxxxxxxxxx> Subject: initramfs: provide a way to ignore image provided by bootloader Many "embedded" architectures provide CMDLINE_FORCE to allow the kernel to override the command line provided by an inflexible bootloader. However there is currrently no way for the kernel to override the initramfs image provided by the bootloader meaning there are still ways for bootloaders to make things difficult for us. Fix this by introducing INITRAMFS_FORCE which can prevent the kernel from loading the bootloader supplied image. We use CMDLINE_FORCE (and its friend CMDLINE_EXTEND) to imply that the system has an inflexible bootloader. This allow us to avoid presenting this config option to users of systems where inflexible bootloaders aren't usually a problem. Link: http://lkml.kernel.org/r/20170217121940.30126-1-daniel.thompson@xxxxxxxxxx Signed-off-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- init/initramfs.c | 2 +- usr/Kconfig | 10 ++++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff -puN init/initramfs.c~initramfs-provide-a-way-to-ignore-image-provided-by-bootloader init/initramfs.c --- a/init/initramfs.c~initramfs-provide-a-way-to-ignore-image-provided-by-bootloader +++ a/init/initramfs.c @@ -613,7 +613,7 @@ static int __init populate_rootfs(void) if (err) panic("%s", err); /* Failed to decompress INTERNAL initramfs */ /* If available load the bootloader supplied initrd */ - if (initrd_start) { + if (initrd_start && !IS_ENABLED(CONFIG_INITRAMFS_FORCE)) { #ifdef CONFIG_BLK_DEV_RAM int fd; printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n"); diff -puN usr/Kconfig~initramfs-provide-a-way-to-ignore-image-provided-by-bootloader usr/Kconfig --- a/usr/Kconfig~initramfs-provide-a-way-to-ignore-image-provided-by-bootloader +++ a/usr/Kconfig @@ -21,6 +21,16 @@ config INITRAMFS_SOURCE If you are not sure, leave it blank. +config INITRAMFS_FORCE + bool "Ignore the initramfs passed by the bootloader" + depends on CMDLINE_EXTEND || CMDLINE_FORCE + help + This option causes the kernel to ignore the initramfs image + (or initrd image) passed to it by the bootloader. This is + analogous to CMDLINE_FORCE, which is found on some architectures, + and is useful if you cannot or don't want to change the image + your bootloader passes to the kernel. + config INITRAMFS_ROOT_UID int "User ID to map to 0 (user root)" depends on INITRAMFS_SOURCE!="" _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
