linux-kernel - Re: [PATCH 0/6] Support calling functions on dedicated physical cpu

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Date:	Fri, 11 Mar 2016 13:15:04 +0000
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
	xen-devel@...ts.xenproject.org, konrad.wilk@...cle.com,
	boris.ostrovsky@...cle.com, david.vrabel@...rix.com,
	mingo@...hat.com, Douglas_Warzecha@...l.com, pali.rohar@...il.com,
	jdelvare@...e.com, linux@...ck-us.net, tglx@...utronix.de,
	hpa@...or.com, x86@...nel.org
Subject: Re: [PATCH 0/6] Support calling functions on dedicated physical cpu

On Fri, 11 Mar 2016 13:25:14 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> On Fri, Mar 11, 2016 at 12:59:28PM +0100, Juergen Gross wrote:
> > Some hardware (e.g. Dell Studio laptops) require special functions to
> > be called on physical cpu 0 in order to avoid occasional hangs. When
> > running as dom0 under Xen this could be achieved only via special boot
> > parameters (vcpu pinning) limiting the hypervisor in it's scheduling
> > decisions.  
> 
> So instead of telling Dell to get their act together and fix their damn
> firmware, we're going to add the most horrid gunk to the kernel? How
> does that make sense?

It's been normal forever. The convention with a lot of older BIOS crap
was always that it should be called on the boot CPU (APM. PnPBIOS etc).

It's a stretch pre-EFI to even call it a "bug"

Alan