It is not used anymore.

Signed-off-by: Askar Safin <safinaskar@gmail.com>
---
 Documentation/admin-guide/sysctl/kernel.rst |  6 ------
 include/uapi/linux/sysctl.h                 |  1 -
 init/do_mounts_initrd.c                     | 20 --------------------
 3 files changed, 27 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index f3ee807b5d8b..218265babaf9 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1215,12 +1215,6 @@ that support this feature.
 ==  ===========================================================================
 
 
-real-root-dev
-=============
-
-See Documentation/admin-guide/initrd.rst.
-
-
 reboot-cmd (SPARC only)
 =======================
 
diff --git a/include/uapi/linux/sysctl.h b/include/uapi/linux/sysctl.h
index 63d1464cb71c..1c7fe0f4dca4 100644
--- a/include/uapi/linux/sysctl.h
+++ b/include/uapi/linux/sysctl.h
@@ -92,7 +92,6 @@ enum
 	KERN_DOMAINNAME=8,	/* string: domainname */
 
 	KERN_PANIC=15,		/* int: panic timeout */
-	KERN_REALROOTDEV=16,	/* real root device to mount after initrd */
 
 	KERN_SPARC_REBOOT=21,	/* reboot command on Sparc */
 	KERN_CTLALTDEL=22,	/* int: allow ctl-alt-del to reboot */
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index fe335dbc95e0..892e69ab41c4 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -8,31 +8,11 @@
 
 unsigned long initrd_start, initrd_end;
 int initrd_below_start_ok;
-static unsigned int real_root_dev;	/* do_proc_dointvec cannot handle kdev_t */
 static int __initdata mount_initrd = 1;
 
 phys_addr_t phys_initrd_start __initdata;
 unsigned long phys_initrd_size __initdata;
 
-#ifdef CONFIG_SYSCTL
-static const struct ctl_table kern_do_mounts_initrd_table[] = {
-	{
-		.procname       = "real-root-dev",
-		.data           = &real_root_dev,
-		.maxlen         = sizeof(int),
-		.mode           = 0644,
-		.proc_handler   = proc_dointvec,
-	},
-};
-
-static __init int kernel_do_mounts_initrd_sysctls_init(void)
-{
-	register_sysctl_init("kernel", kern_do_mounts_initrd_table);
-	return 0;
-}
-late_initcall(kernel_do_mounts_initrd_sysctls_init);
-#endif /* CONFIG_SYSCTL */
-
 static int __init no_initrd(char *str)
 {
 	pr_warn("noinitrd option is deprecated and will be removed soon\n");
-- 
2.47.3

On Wed, Nov 19, 2025 at 10:24:07PM +0000, Askar Safin wrote:
> It is not used anymore.

Let's hope whacky userspace agrees with that :)

But we'll have to try this to find out, so:

Reviewed-by: Christoph Hellwig <hch@lst.de>

On Mon, Nov 24, 2025 at 03:28:04PM +0100, Christoph Hellwig wrote:
> On Wed, Nov 19, 2025 at 10:24:07PM +0000, Askar Safin wrote:
> > It is not used anymore.
> 
> Let's hope whacky userspace agrees with that :)
> 
> But we'll have to try this to find out, so:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Ok, let's try for v6.20. Putting this into vfs-6.20.initrd.