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authorClark Williams <williams@redhat.com>2011-07-30 21:55:53 -0500
committerClark Williams <williams@redhat.com>2012-04-10 16:37:31 -0500
commit8572f5439b93d901937148ce24e665f3019f70ad (patch)
treeaf9894af498c4d1e6bf5b00d75c7d7c1fcb7a619
parent5a4cd2febf65ca908c2f7fbe9db387d4a909aad1 (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 4e316e1acf58..a546d3303a2c 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -133,6 +133,15 @@ 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)
@@ -182,6 +191,9 @@ static struct attribute * kernel_attrs[] = {
&kexec_crash_size_attr.attr,
&vmcoreinfo_attr.attr,
#endif
+#ifdef CONFIG_PREEMPT_RT_FULL
+ &realtime_attr.attr,
+#endif
NULL
};