Messages in this thread | | | Date | Thu, 21 Nov 2019 18:14:01 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter |
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* Fenghua Yu <fenghua.yu@intel.com> wrote:
> > This feature MUST be default enabled, otherwise everything will > > be/remain broken and we'll end up in the situation where you can't > > use it even if you wanted to. > > The usage scope of this patch set is largely reduced to only real time. > The long split lock processing time (>1000 cycles) cannot be tolerated > by real time. > > Real time customers do want to use this feature to detect the fatal > split lock error. They don't want any split lock issue from BIOS/EFI/ > firmware/kerne/drivers/user apps. > > Real time can enable the feature (set bit 29 in TEST_CTRL MSR) in BIOS > and don't need OS to enable it. But, #AC handler cannot handle split > lock in the kernel and will return to the faulting instruction and > re-enter #AC. So current #AC handler doesn't provide useful information > for the customers. That's why we add the new #AC handler in this patch > set.
Immaterial - for this feature to be useful it must be default-enabled, with reasonable quirk knobs offered to people who happen to be bitten by such bugs and cannot fix the software.
But default-enabled is a must-have, as Peter said.
Thanks,
Ingo
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