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Subject[PATCH 4/4] Documentation/admin-guide: Change doc for split_lock_detect parameter
Date
Since #DB for bus lock detect changes the split_lock_detect parameter,
update the documentation for the changes.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Change Log:
- Fix a few wording issues (Randy).

RFC v2:
- Simplify the documentation (Randy).

.../admin-guide/kernel-parameters.txt | 30 +++++++++++++++----
1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 526d65d8573a..215e119f6ca7 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5044,27 +5044,45 @@
spia_peddr=

split_lock_detect=
- [X86] Enable split lock detection
+ [X86] Enable split lock detection or bus lock detection

When enabled (and if hardware support is present), atomic
instructions that access data across cache line
- boundaries will result in an alignment check exception.
+ boundaries will result in an alignment check exception
+ for split lock detection or a debug exception for
+ bus lock detection.

off - not enabled

- warn - the kernel will emit rate limited warnings
+ warn - the kernel will emit rate-limited warnings
about applications triggering the #AC
- exception. This mode is the default on CPUs
- that supports split lock detection.
+ exception or the #DB exception. This mode is
+ the default on CPUs that support split lock
+ detection or bus lock detection. Default
+ behavior is by #DB if both features are
+ enabled in hardware.

fatal - the kernel will send SIGBUS to applications
- that trigger the #AC exception.
+ that trigger the #AC exception or the #DB
+ exception. Default behavior is by #AC
+ if both features are enabled in hardware.
+
+ ratelimit:N -
+ Set rate limit to N bus locks per second
+ for bus lock detection. 0 < N <= HZ/2 and
+ N is approximate. Only applied to non-root
+ users.
+
+ N/A for split lock detection.

If an #AC exception is hit in the kernel or in
firmware (i.e. not while executing in user mode)
the kernel will oops in either "warn" or "fatal"
mode.

+ #DB exception for bus lock is triggered only when
+ CPL > 0.
+
srbds= [X86,INTEL]
Control the Special Register Buffer Data Sampling
(SRBDS) mitigation.
--
2.29.2
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