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authorClark Williams <williams@redhat.com>2011-07-30 21:55:53 -0500
committerSteven Rostedt <rostedt@goodmis.org>2012-01-24 11:04:54 -0500
commit3925d147d6d6fbb346ca4847af1989c458659159 (patch)
tree071ca9ececdfe82986926a700f51877ec9ee1487
parentb45dd5d6132cba5bc8da6fcb4b1658314ba6010e (diff)
add /sys/kernel/realtime entry
Add a /sys/kernel entry to indicate that the kernel is a realtime kernel. Clark says that he needs this for udev rules, udev needs to evaluate if its a PREEMPT_RT kernel a few thousand times and parsing uname output is too slow or so. Are there better solutions? Should it exist and return 0 on !-rt? Signed-off-by: Clark Williams <williams@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
-rw-r--r--kernel/ksysfs.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 3b053c04dd86..915b5226b819 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -132,6 +132,15 @@ KERNEL_ATTR_RO(vmcoreinfo);
#endif /* CONFIG_KEXEC */
+#if defined(CONFIG_PREEMPT_RT_FULL)
+static ssize_t realtime_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", 1);
+}
+KERNEL_ATTR_RO(realtime);
+#endif
+
/* whether file capabilities are enabled */
static ssize_t fscaps_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
@@ -181,6 +190,9 @@ static struct attribute * kernel_attrs[] = {
&kexec_crash_size_attr.attr,
&vmcoreinfo_attr.attr,
#endif
+#ifdef CONFIG_PREEMPT_RT_FULL
+ &realtime_attr.attr,
+#endif
NULL
};