By default, #AC for split lock is enabled. In some cases (e.g. system hang when firmware hits split lock), user may want to opt-out of the feature.
Kernel parameter "ac_split_lock_off" disables the feature during boot time. Signed-off-by: Fenghua Yu <[email protected]> --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ arch/x86/kernel/cpu/test_ctl.c | 9 +++++++++ 2 files changed, 13 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index efc7aa7a0670..7bf3b37dccdb 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4086,6 +4086,10 @@ spia_pedr= spia_peddr= + ac_split_lock_off [X86] + Disable #AC exception for split locked accesses. + By default, this feature is enabled in kernel. + srcutree.counter_wrap_check [KNL] Specifies how frequently to check for grace-period sequence counter wrap for the diff --git a/arch/x86/kernel/cpu/test_ctl.c b/arch/x86/kernel/cpu/test_ctl.c index f12e8b24215d..4e6ed267e8b7 100644 --- a/arch/x86/kernel/cpu/test_ctl.c +++ b/arch/x86/kernel/cpu/test_ctl.c @@ -85,3 +85,12 @@ void setup_ac_split_lock(void) pr_info_once("#AC for split lock is disabled\n"); } } + +static __init int ac_split_lock_off(char *str) +{ + enable_ac_split_lock = false; + + return 0; +} + +early_param("ac_split_lock_off", ac_split_lock_off); -- 2.5.0
