Re: [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses

[Thomas Gleixner]

On Thu, 21 Jun 2018, Fenghua Yu wrote:
> Right. Code won't cover the early boot process. It only covers boot process
> after the feature is enabled.

That's broken. #AC wants to be enabled early as any other exception. The
reason why you cannot enable it is because your exception handler is a
total trainwreck, but it's even a trainwreck later on.

> After disabling #AC split lock after catching #AC once, any future split
> lock will not generate #AC any more.

That's perfectly fine for the kernel. Issue a prominent warning and stuff
gets fixed.

Thanks,

	tglx