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@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Daniel Thompson
2017-05-08 15:56:57 -07:00
committed by Linus Torvalds
parent da5e108b02
commit cff75e0b6f
2 changed files with 11 additions and 1 deletions

View File

@@ -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");