[PATCH v9 15/17] x86/split_lock: Add documentation for split lock detection interface

From: Fenghua Yu
Date: Tue Jun 18 2019 - 18:56:55 EST

It is useful for development and debugging to document the new debugfs
interface /sys/kernel/debug/x86/split_lock_detect.

A new debugfs documentation is created to describe the split lock detection
interface. In the future, more entries may be added in the documentation to
describe other interfaces under /sys/kernel/debug/x86 directory.

Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Documentation/ABI/testing/debugfs-x86 | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
create mode 100644 Documentation/ABI/testing/debugfs-x86

diff --git a/Documentation/ABI/testing/debugfs-x86 b/Documentation/ABI/testing/debugfs-x86
new file mode 100644
index 000000000000..17a1e9ed6712
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-x86
@@ -0,0 +1,21 @@
+What: /sys/kernel/debugfs/x86/split_lock_detect
+Date: May 2019
+Contact: Linux kernel mailing list <linux-kernel@xxxxxxxxxxxxxxx>
+Description: (RW) Control split lock detection on Intel Tremont and
+ future CPUs
+ Reads return split lock detection status:
+ 0: disabled
+ 1: enabled
+ Writes enable or disable split lock detection:
+ The first character is one of 'Nn0' or [oO][fF] for off
+ disables the feature.
+ The first character is one of 'Yy1' or [oO][nN] for on
+ enables the feature.
+ Please note the interface only shows or controls global setting.
+ During run time, split lock detection on one CPU may be
+ disabled if split lock operation in kernel code happens on
+ the CPU. The interface doesn't show or control split lock
+ detection on individual CPU.