initrd: remove deprecated code path (linuxrc)

Remove linuxrc initrd code path, which was deprecated in 2020.

Initramfs and (non-initial) RAM disks (i. e. brd) still work.

Both built-in and bootloader-supplied initramfs still work.

Non-linuxrc initrd code path (i. e. using /dev/ram as final root
filesystem) still works, but I put deprecation message into it.

Also I deprecate command line parameters "noinitrd" and "ramdisk_start=".

Signed-off-by: Askar Safin <safinaskar@gmail.com>
Link: https://patch.msgid.link/20251119222407.3333257-3-safinaskar@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4bdf6a158181e815aea4ee7dbc68ade484b12134..f67591615a6adfdac112dc7842c889167dd0b868 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4442,8 +4442,10 @@ Kernel parameters
                        Note that this argument takes precedence over
                        the CONFIG_RCU_NOCB_CPU_DEFAULT_ALL option.
 
-       noinitrd        [RAM] Tells the kernel not to load any configured
-                       initial RAM disk.
+       noinitrd        [Deprecated,RAM] Tells the kernel not to load any configured
+                       initial RAM disk. Currently this parameter applies to
+                       initrd only, not to initramfs. But it applies to both
+                       in EFI mode.
 
        nointremap      [X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
                        remapping.
@@ -5456,7 +5458,7 @@ Kernel parameters
        ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
                        See Documentation/admin-guide/blockdev/ramdisk.rst.
 
-       ramdisk_start=  [RAM] RAM disk image start address
+       ramdisk_start=  [Deprecated,RAM] RAM disk image start address
 
        random.trust_cpu=off
                        [KNL,EARLY] Disable trusting the use of the CPU's

diff --git a/include/linux/initrd.h b/include/linux/initrd.h
index f1a1f4c92ded3921bf56d53bee3e20b549d851fb..7e5d26c8136f19a208ea6c9fd90e77ab7acb0e02 100644 (file)
--- a/include/linux/initrd.h
+++ b/include/linux/initrd.h
@@ -3,8 +3,6 @@
 #ifndef __LINUX_INITRD_H
 #define __LINUX_INITRD_H
 
-#define INITRD_MINOR 250 /* shouldn't collide with /dev/ram* too soon ... */
-
 /* starting block # of image */
 extern int rd_image_start;
 

diff --git a/init/do_mounts.c b/init/do_mounts.c
index 3b9f0d9216583936c410260361924b4351f880f1..9c8a547075a7bc06cd5bc85465c2e680e35df9b4 100644 (file)
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -477,13 +477,11 @@ void __init prepare_namespace(void)
        if (saved_root_name[0])
                ROOT_DEV = parse_root_device(saved_root_name);
 
-       if (initrd_load(saved_root_name))
-               goto out;
+       initrd_load();
 
        if (root_wait)
                wait_for_root(saved_root_name);
        mount_root(saved_root_name);
-out:
        devtmpfs_mount();
        init_mount(".", "/", NULL, MS_MOVE, NULL);
        init_chroot(".");

diff --git a/init/do_mounts.h b/init/do_mounts.h
index 6069ea3eb80d70106d6a8d8b3515d50176353206..a386ee5314c952da6edf287dba30f575fd6808da 100644 (file)
--- a/init/do_mounts.h
+++ b/init/do_mounts.h
@@ -23,25 +23,15 @@ static inline __init int create_dev(char *name, dev_t dev)
 }
 
 #ifdef CONFIG_BLK_DEV_RAM
-
-int __init rd_load_disk(int n);
-int __init rd_load_image(char *from);
-
+int __init rd_load_image(void);
 #else
-
-static inline int rd_load_disk(int n) { return 0; }
-static inline int rd_load_image(char *from) { return 0; }
-
+static inline int rd_load_image(void) { return 0; }
 #endif
 
 #ifdef CONFIG_BLK_DEV_INITRD
-bool __init initrd_load(char *root_device_name);
+void __init initrd_load(void);
 #else
-static inline bool initrd_load(char *root_device_name)
-{
-       return false;
-       }
-
+static inline void initrd_load(void) { }
 #endif
 
 /* Ensure that async file closing finished to prevent spurious errors. */

diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index f6867bad0d782cbf0eb44c7341f1a192e3f23e43..fe335dbc95e0fa616c7b06955f74e6704684c6b9 100644 (file)
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -2,13 +2,7 @@
 #include <linux/unistd.h>
 #include <linux/kernel.h>
 #include <linux/fs.h>
-#include <linux/minix_fs.h>
-#include <linux/romfs_fs.h>
 #include <linux/initrd.h>
-#include <linux/sched.h>
-#include <linux/freezer.h>
-#include <linux/kmod.h>
-#include <uapi/linux/mount.h>
 
 #include "do_mounts.h"
 
@@ -41,6 +35,7 @@ late_initcall(kernel_do_mounts_initrd_sysctls_init);
 
 static int __init no_initrd(char *str)
 {
+       pr_warn("noinitrd option is deprecated and will be removed soon\n");
        mount_initrd = 0;
        return 1;
 }
@@ -70,85 +65,19 @@ static int __init early_initrd(char *p)
 }
 early_param("initrd", early_initrd);
 
-static int __init init_linuxrc(struct subprocess_info *info, struct cred *new)
-{
-       ksys_unshare(CLONE_FS | CLONE_FILES);
-       console_on_rootfs();
-       /* move initrd over / and chdir/chroot in initrd root */
-       init_chdir("/root");
-       init_mount(".", "/", NULL, MS_MOVE, NULL);
-       init_chroot(".");
-       ksys_setsid();
-       return 0;
-}
-
-static void __init handle_initrd(char *root_device_name)
-{
-       struct subprocess_info *info;
-       static char *argv[] = { "linuxrc", NULL, };
-       extern char *envp_init[];
-       int error;
-
-       pr_warn("using deprecated initrd support, will be removed soon.\n");
-
-       real_root_dev = new_encode_dev(ROOT_DEV);
-       create_dev("/dev/root.old", Root_RAM0);
-       /* mount initrd on rootfs' /root */
-       mount_root_generic("/dev/root.old", root_device_name,
-                          root_mountflags & ~MS_RDONLY);
-       init_mkdir("/old", 0700);
-       init_chdir("/old");
-
-       info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
-                                        GFP_KERNEL, init_linuxrc, NULL, NULL);
-       if (!info)
-               return;
-       call_usermodehelper_exec(info, UMH_WAIT_PROC|UMH_FREEZABLE);
-
-       /* move initrd to rootfs' /old */
-       init_mount("..", ".", NULL, MS_MOVE, NULL);
-       /* switch root and cwd back to / of rootfs */
-       init_chroot("..");
-
-       if (new_decode_dev(real_root_dev) == Root_RAM0) {
-               init_chdir("/old");
-               return;
-       }
-
-       init_chdir("/");
-       ROOT_DEV = new_decode_dev(real_root_dev);
-       mount_root(root_device_name);
-
-       printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
-       error = init_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
-       if (!error)
-               printk("okay\n");
-       else {
-               if (error == -ENOENT)
-                       printk("/initrd does not exist. Ignored.\n");
-               else
-                       printk("failed\n");
-               printk(KERN_NOTICE "Unmounting old root\n");
-               init_umount("/old", MNT_DETACH);
-       }
-}
-
-bool __init initrd_load(char *root_device_name)
+void __init initrd_load(void)
 {
        if (mount_initrd) {
                create_dev("/dev/ram", Root_RAM0);
                /*
-                * Load the initrd data into /dev/ram0. Execute it as initrd
-                * unless /dev/ram0 is supposed to be our actual root device,
-                * in that case the ram disk is just set up here, and gets
-                * mounted in the normal path.
+                * Load the initrd data into /dev/ram0.
                 */
-               if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
-                       init_unlink("/initrd.image");
-                       handle_initrd(root_device_name);
-                       return true;
+               if (rd_load_image()) {
+                       pr_warn("using deprecated initrd support, will be removed in January 2027; "
+                               "use initramfs instead or (as a last resort) /sys/firmware/initrd; "
+                               "see section \"Workaround\" in "
+                               "https://lore.kernel.org/lkml/20251010094047.3111495-1-safinaskar@gmail.com\n");
                }
        }
        init_unlink("/initrd.image");
-       return false;
 }

diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
index d20fabf2227fd12e9e084232a2f4cbd5e4688bfa..48bfab2fc62f912c481ffc75995cee3f798289b7 100644 (file)
--- a/init/do_mounts_rd.c
+++ b/init/do_mounts_rd.c
@@ -22,6 +22,7 @@ int __initdata rd_image_start;                /* starting block # of image */
 
 static int __init ramdisk_start_setup(char *str)
 {
+       pr_warn("ramdisk_start= option is deprecated and will be removed soon\n");
        return kstrtoint(str, 0, &rd_image_start) == 0;
 }
 __setup("ramdisk_start=", ramdisk_start_setup);
@@ -176,7 +177,7 @@ static unsigned long nr_blocks(struct file *file)
        return i_size_read(inode) >> 10;
 }
 
-int __init rd_load_image(char *from)
+int __init rd_load_image(void)
 {
        int res = 0;
        unsigned long rd_blocks, devblocks, nr_disks;
@@ -190,7 +191,7 @@ int __init rd_load_image(char *from)
        if (IS_ERR(out_file))
                goto out;
 
-       in_file = filp_open(from, O_RDONLY, 0);
+       in_file = filp_open("/initrd.image", O_RDONLY, 0);
        if (IS_ERR(in_file))
                goto noclose_input;
 
@@ -219,10 +220,7 @@ int __init rd_load_image(char *from)
        /*
         * OK, time to copy in the data
         */
-       if (strcmp(from, "/initrd.image") == 0)
-               devblocks = nblocks;
-       else
-               devblocks = nr_blocks(in_file);
+       devblocks = nblocks;
 
        if (devblocks == 0) {
                printk(KERN_ERR "RAMDISK: could not determine device size\n");
@@ -266,13 +264,6 @@ out:
        return res;
 }
 
-int __init rd_load_disk(int n)
-{
-       create_dev("/dev/root", ROOT_DEV);
-       create_dev("/dev/ram", MKDEV(RAMDISK_MAJOR, n));
-       return rd_load_image("/dev/root");
-}
-
 static int exit_code;
 static int decompress_error;