Re: [RFD] x86/tsc: Loosen the requirements for watchdog - (was x86/hpet: Disable HPET on Intel Coffe Lake)

From: Daniel Drake
Date: Thu Aug 29 2019 - 23:47:17 EST

Hi Thomas,

On Fri, Aug 30, 2019 at 5:38 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> So if we have to disable the HPET on Kaby Lake alltogether unless Intel
> comes up with the clever fix, i.e. poking at the right registers, then I
> think we should also lift the TSC watchdog restrictions on these machines
> if they are single socket, which they are as the affected CPUs so far are
> mobile and client types.
> Also given the fact that we get more and more 'reduced' hardware exposed
> via ACPI and we already dealt with quite some fallout with various related
> issues due to that, I fear we need to bite this bullet anyway anytime soon.

Thanks for the explanation here!

My experience in this area is basically limited to the clock-related
issues that I've sent your way recently, so I don't have deep wisdom
to draw upon, but what you wrote here makes sense to me.

If you can outline a testing procedure, we can test upcoming patches
on Coffee Lake and Kaby Lake consumer laptops.