[PATCH] Add a sysfs file to determine if a kexec kernel is loaded
Create two files in /sys/kernel, kexec_loaded and kexec_crash_loaded. Each
file contains a simple boolean value indicating whether the relevant kernel
has been loaded into memory. The motivation for this is geared around
support.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index f119e09..9e28478 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -14,6 +14,7 @@
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/init.h>
+#include <linux/kexec.h>
#define KERNEL_ATTR_RO(_name) \
static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
@@ -48,6 +49,20 @@
KERNEL_ATTR_RW(uevent_helper);
#endif
+#ifdef CONFIG_KEXEC
+static ssize_t kexec_loaded_show(struct subsystem *subsys, char *page)
+{
+ return sprintf(page, "%d\n", !!kexec_image);
+}
+KERNEL_ATTR_RO(kexec_loaded);
+
+static ssize_t kexec_crash_loaded_show(struct subsystem *subsys, char *page)
+{
+ return sprintf(page, "%d\n", !!kexec_crash_image);
+}
+KERNEL_ATTR_RO(kexec_crash_loaded);
+#endif /* CONFIG_KEXEC */
+
decl_subsys(kernel, NULL, NULL);
EXPORT_SYMBOL_GPL(kernel_subsys);
@@ -56,6 +71,10 @@
&uevent_seqnum_attr.attr,
&uevent_helper_attr.attr,
#endif
+#ifdef CONFIG_KEXEC
+ &kexec_loaded_attr.attr,
+ &kexec_crash_loaded_attr.attr,
+#endif
NULL
};