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Documentation/admin-guide: Change doc for split_lock_detect parameter

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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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20210322135325.682257-4-fenghua.yu@intel.com
This commit is contained in:
Fenghua Yu 2021-03-22 13:53:25 +00:00 committed by Thomas Gleixner
parent ebb1064e7c
commit ebca17707e
1 changed files with 16 additions and 6 deletions
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22
Documentation/admin-guide/kernel-parameters.txt
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@ -5100,27 +5100,37 @@
spia_peddr= spia_peddr=
split_lock_detect= 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 When enabled (and if hardware support is present), atomic
instructions that access data across cache line 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 off - not enabled
warn - the kernel will emit rate limited warnings warn - the kernel will emit rate-limited warnings
about applications triggering the #AC about applications triggering the #AC
exception. This mode is the default on CPUs exception or the #DB exception. This mode is
that supports split lock detection. the default on CPUs that support split lock
detection or bus lock detection. Default
behavior is by #AC if both features are
enabled in hardware.
fatal - the kernel will send SIGBUS to applications 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.
If an #AC exception is hit in the kernel or in If an #AC exception is hit in the kernel or in
firmware (i.e. not while executing in user mode) firmware (i.e. not while executing in user mode)
the kernel will oops in either "warn" or "fatal" the kernel will oops in either "warn" or "fatal"
mode. mode.
#DB exception for bus lock is triggered only when
CPL > 0.
srbds= [X86,INTEL] srbds= [X86,INTEL]
Control the Special Register Buffer Data Sampling Control the Special Register Buffer Data Sampling
(SRBDS) mitigation. (SRBDS) mitigation.