Hi,
On 10/30/20 5:27 PM, Fenghua Yu wrote:
> Since #DB for bus lock detect changes the split_lock_detect parameter,
> update the documentation for the changes.
>
> Signed-off-by: Fenghua Yu <fenghua...@intel.com>
> Reviewed-by: Tony Luck <tony.l...@intel.com>
> ---
> Change Log:
> - Simplify the documentation (Randy).
>
> .../admin-guide/kernel-parameters.txt | 28 +++++++++++++++----
> 1 file changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 526d65d8573a..ee419ce659f5 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
rate-limited
> 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 supports split lock
support
> + detection or bus lock detection. Default
> + behavior is from #DB if both features are
I would say is by #DB
> + 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 from #AC
and 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
non-root
> + user.
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.
> +
thanks.
--
~Randy
