Re: Regression: unable to boot after commit bd9240a18edf ("x86/apic: Add TSC_DEADLINE quirk due to errata") - Surface Pro 4 SKL

[Zhang Rui]

On Tue, 2017-11-28 at 13:36 +0100, Peter Zijlstra wrote:
> On Tue, Nov 28, 2017 at 06:59:01PM +0800, Zhang Rui wrote:
> > 
> > > 
> > > > 
> > > > > 
> > > > > > 
> > > > > > My Surface Pro 4 is unable to boot after 4.12. The symptom
> > > > > > is
> > 
> > yes. Tried 4.4 distro and 4.12 vanilla kernel, kernel always
> > freezes
> > with boot option "notscdeadline"/"lapic=notscdeadline".
> Then for some mysterious reason, your Surface thing has a borked
> LAPIC.
> 
I agree. But however, on this platform, forcing a cpu microcode upgrade
after upgrading kernel does not seem like a good solution to users.
Thus I still like to dig into the problem further to see if we can
workaround this "regression" in software.
As the kernel freezes at a very early stage, do you have any advice on
how to narrow down the problem?

thanks,
rui