kexec: add sysctl to disable kexec_load

[uclinux-h8/linux.git] / Documentation / sysctl / kernel.txt

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 6d48640..ee9a2f9 100644 (file)
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -33,6 +33,7 @@ show up in /proc/sys/kernel:
 - domainname
 - hostname
 - hotplug
+- kexec_load_disabled
 - kptr_restrict
 - kstack_depth_to_print       [ X86 only ]
 - l2cr                        [ PPC only ]
@@ -287,6 +288,18 @@ Default value is "/sbin/hotplug".
 
 ==============================================================
 
+kexec_load_disabled:
+
+A toggle indicating if the kexec_load syscall has been disabled. This
+value defaults to 0 (false: kexec_load enabled), but can be set to 1
+(true: kexec_load disabled). Once true, kexec can no longer be used, and
+the toggle cannot be set back to false. This allows a kexec image to be
+loaded before disabling the syscall, allowing a system to set up (and
+later use) an image without it being altered. Generally used together
+with the "modules_disabled" sysctl.
+
+==============================================================
+
 kptr_restrict:
 
 This toggle indicates whether restrictions are placed on
@@ -331,7 +344,7 @@ A toggle value indicating if modules are allowed to be loaded
 in an otherwise modular kernel.  This toggle defaults to off
 (0), but can be set true (1).  Once true, modules can be
 neither loaded nor unloaded, and the toggle cannot be set back
-to false.
+to false.  Generally used with the "kexec_load_disabled" toggle.
 
 ==============================================================