linux-kernel - RE: [PATCH] ACPI: don't show an error when we're not in charge of PCIe hotplug.

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Message-ID: <d117d2c7b63446d098aa93f88a2b5686@ausx13mpc124.AMER.DELL.COM>
Date:	Thu, 23 Jun 2016 15:38:04 +0000
From:	<Mario_Limonciello@...l.com>
To:	<rafael@...nel.org>, <luto@...capital.net>
CC:	<pjones@...hat.com>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <lenb@...nel.org>,
	<rjw@...ysocki.net>
Subject: RE: [PATCH] ACPI: don't show an error when we're not in charge of
 PCIe hotplug.

> -----Original Message-----
> From: rjwysocki@...il.com [mailto:rjwysocki@...il.com] On Behalf Of
> Rafael J. Wysocki
> Sent: Wednesday, June 22, 2016 5:48 PM
> To: Andy Lutomirski <luto@...capital.net>; Limonciello, Mario
> <Mario_Limonciello@...l.com>
> Cc: Rafael Wysocki <rafael@...nel.org>; Peter Jones <pjones@...hat.com>;
> Linux ACPI <linux-acpi@...r.kernel.org>; linux-kernel@...r.kernel.org; Len
> Brown <lenb@...nel.org>; Rafael J. Wysocki <rjw@...ysocki.net>
> Subject: Re: [PATCH] ACPI: don't show an error when we're not in charge of
> PCIe hotplug.
> 
> On Wed, Jun 22, 2016 at 10:53 PM, Andy Lutomirski <luto@...capital.net>
> wrote:
> > On Wed, Jun 22, 2016 at 12:43 PM,  <Mario_Limonciello@...l.com> wrote:
> >>> -----Original Message-----
> >>> From: rjwysocki@...il.com [mailto:rjwysocki@...il.com] On Behalf Of
> 
> [cut]
> 
> >> I think changing that would help communicate what's going on here and at
> >> least let the user know the result will be that the firmware is still
> controlling
> >> ASPM due to the _OSC failure.
> 
> You seem to be assuming that all systems returning "unsupported UUID"
> from the PCI host bridge _OSC will always fall into the same category,
> but what if they don't?  What if at least some of them are really
> broken?
> 

Even if they are broken, the net result will be the firmware is in control
of ASPM, won't it?  At least outside of the group on this mailing list that
might not be very apparent from the current set of errors output into
logs.

> >> Something else that I think Andy recommended a while back was at that
> >> time try to evaluate NEXP and display its value and an associated message
> >> in debug logs when _OSC fails.  Would you be amenable to a change like
> that?
> >
> > That seems dangerous if NEXP is anything other than a SystemMemory
> > variable.  I don't know if there's a clean way to check that before
> > evaluating it.  (i.e. we don't want to hit some other thing called
> > NEXP that has side effects.)
> 
> Well, that's generic code and NEXP is not generic really, so agreed.

OK.