Re: [Xen-devel] Re: [PATCH RFC] x86/acpi: don't ignore I/O APICs just because there's no local APIC

From: ebiederm@xmission.com (Eric W. Biederman)
To: Keir Fraser <keir.fraser@eu.citrix.com>
Cc: "Nakajima\, Jun" <jun.nakajima@intel.com>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	Xen-devel <xen-devel@lists.xensource.com>,
	the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>, Len Brown <lenb@kernel.org>
Subject: Re: [Xen-devel] Re: [PATCH RFC] x86/acpi: don't ignore I/O APICs just because there's no local APIC
Date: Sat, 20 Jun 2009 01:21:47 -0700	[thread overview]
Message-ID: <m1ljnnnwmc.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <C66250DB.DC85%keir.fraser@eu.citrix.com> (Keir Fraser's message of "Sat\, 20 Jun 2009 08\:39\:55 +0100")

Keir Fraser <keir.fraser@eu.citrix.com> writes:

> On 20/06/2009 00:44, "Nakajima, Jun" <jun.nakajima@intel.com> wrote:
>
>>> I assume that putting AML into Xen has been considered, but I don't
>>> anything about those deliberations.  Keir? Jun?
>>> 
>> 
>> Yes, it was one of the options years ago. We did not do that because Linux and
>> Solaris (as dom0) already had the AML interpreter and it's overkill and
>> redundant to have such a large component in the Xen hypervisor. Since the
>> hypervisor does most of the power management (i.e. P, C, S-state, etc.)
>> getting the info from dom0 today, we might want to reconsider the option.
>
> Yes, we could reconsider. However is there any stuff that dom0 remains
> responsible for (e.g., PCI management, and therefore PCI hotplug) where it
> would continue to need to be OSPM, interpreting certain AML objects? In
> general how safe would it be to have two layered entities both playing at
> being OSPM?

Short of running the oddball acpi based drivers.  I'm not familiar with
any acpi in the pci management.

Eric