From a976c3e3f9e55c0e87d58b6487811d71ed0c9c80 Mon Sep 17 00:00:00 2001 From: Clark Williams Date: Sat, 30 Jul 2011 21:55:53 -0500 Subject: [PATCH 183/184] sysfs: 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 Signed-off-by: Peter Zijlstra Signed-off-by: Thomas Gleixner --- kernel/ksysfs.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index 1d4bc493b2f4..486c68c11bbe 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -179,6 +179,15 @@ KERNEL_ATTR_RO(crash_elfcorehdr_size); #endif /* CONFIG_CRASH_CORE */ +#if defined(CONFIG_PREEMPT_RT) +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) @@ -274,6 +283,9 @@ static struct attribute * kernel_attrs[] = { #ifndef CONFIG_TINY_RCU &rcu_expedited_attr.attr, &rcu_normal_attr.attr, +#endif +#ifdef CONFIG_PREEMPT_RT + &realtime_attr.attr, #endif NULL }; -- 2.34.1