linux/init
Alexander Graf 2678fd2fe9 initramfs: Expose retained initrd as sysfs file
When the kernel command line option "retain_initrd" is set, we do not
free the initrd memory. However, we also don't expose it to anyone for
consumption. That leaves us in a weird situation where the only user of
this feature is ppc64 and arm64 specific kexec tooling.

To make it more generally useful, this patch adds a kobject to the
firmware object that contains the initrd context when "retain_initrd"
is set. That way, we can access the initrd any time after boot from
user space and for example hand it into kexec as --initrd parameter
if we want to reboot the same initrd. Or inspect it directly locally.

With this patch applied, there is a new /sys/firmware/initrd file when
the kernel was booted with an initrd and "retain_initrd" command line
option is set.

Signed-off-by: Alexander Graf <graf@amazon.com>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20231207235654.16622-1-graf@amazon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-12-15 17:23:00 +01:00
..
.gitignore kbuild: build init/built-in.a just once 2022-09-29 04:40:15 +09:00
build-version kbuild: build init/built-in.a just once 2022-09-29 04:40:15 +09:00
calibrate.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
do_mounts_initrd.c init: pass root_device_name explicitly 2023-06-05 10:55:20 -06:00
do_mounts_rd.c init: add an init_unlink helper 2020-07-31 08:17:52 +02:00
do_mounts.c init/mount: print pretty name of root device when panics 2023-10-19 11:02:46 +02:00
do_mounts.h init: pass root_device_name explicitly 2023-06-05 10:55:20 -06:00
init_task.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
initramfs.c initramfs: Expose retained initrd as sysfs file 2023-12-15 17:23:00 +01:00
Kconfig arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
main.c proc: sysctl: prevent aliased sysctls from getting passed to init 2023-11-01 12:10:02 -07:00
Makefile x86/retpoline: Make sure there are no unconverted return thunks due to KCSAN 2023-10-20 13:02:23 +02:00
noinitramfs.c init: move usermodehelper_enable() to populate_rootfs() 2021-09-08 11:50:27 -07:00
version-timestamp.c init/version-timestamp.c: remove unneeded #include <linux/version.h> 2023-01-09 07:34:38 +09:00
version.c init/version.c: Replace strlcpy with strscpy 2023-09-22 09:50:56 -07:00