49 lines
1.4 KiB
Diff
49 lines
1.4 KiB
Diff
Subject: sysfs: Add /sys/kernel/realtime entry
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From: Clark Williams <williams@redhat.com>
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Date: Sat Jul 30 21:55:53 2011 -0500
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.1-rt3.tar.xz
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Add a /sys/kernel entry to indicate that the kernel is a
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realtime kernel.
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Clark says that he needs this for udev rules, udev needs to evaluate
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if its a PREEMPT_RT kernel a few thousand times and parsing uname
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output is too slow or so.
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Are there better solutions? Should it exist and return 0 on !-rt?
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Signed-off-by: Clark Williams <williams@redhat.com>
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Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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---
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kernel/ksysfs.c | 12 ++++++++++++
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1 file changed, 12 insertions(+)
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--- a/kernel/ksysfs.c
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+++ b/kernel/ksysfs.c
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@@ -140,6 +140,15 @@ KERNEL_ATTR_RO(vmcoreinfo);
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#endif /* CONFIG_CRASH_CORE */
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+#if defined(CONFIG_PREEMPT_RT_FULL)
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+static ssize_t realtime_show(struct kobject *kobj,
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+ struct kobj_attribute *attr, char *buf)
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+{
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+ return sprintf(buf, "%d\n", 1);
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+}
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+KERNEL_ATTR_RO(realtime);
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+#endif
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+
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/* whether file capabilities are enabled */
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static ssize_t fscaps_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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@@ -231,6 +240,9 @@ static struct attribute * kernel_attrs[]
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&rcu_expedited_attr.attr,
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&rcu_normal_attr.attr,
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#endif
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+ &realtime_attr.attr,
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+#endif
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NULL
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};
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