From: Jeremy Fitzhardinge <jeremy@goop.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Xen-devel <xen-devel@lists.xensource.com>
Subject: Re: [PATCH RFC] x86/acpi: don't ignore I/O APICs just because there's no local APIC
Date: Sun, 14 Jun 2009 19:06:43 -0700 [thread overview]
Message-ID: <4A35ACB3.9040501@goop.org> (raw)
In-Reply-To: <m1d499yyug.fsf@fess.ebiederm.org>
On 06/12/09 13:35, Eric W. Biederman wrote:
> Jeremy Fitzhardinge<jeremy@goop.org> writes:
>
>
>> Parse the ACPI MADT for I/O APIC information, even if the cpu has no
>> (apparent) local APIC (ie, the CPU's APIC feature flag is clear).
>>
>> In principle, the local APIC and the I/O APIC are distinct (but related)
>> components, which can be independently present.
>>
>> In practice this can happen in a Xen system, where the hypervisor has
>> full control over the local APICs, and delivers interrupts initiated by
>> the I/O APICs via Xen's event channel mechanism.
>>
>
> Xen is giving us a semi bogus acpi table?
>
No, not really. The guest is reading the real BIOS-provided ACPI
tables, but Xen is clobbering the APIC feature in CPUID so the virtual
CPU doesn't appear to have a usable local APIC. Xen itself doesn't care
very much about interrupt routing or ACPI, and doesn't make any attempt
to read or parse the ACPI data itself (except for very basic things like
the APIC addresses).
> What is the paravirt configuration model with Xen? Is it documented
> somewhere?
>
Not very well. The basic idea is that Xen owns the local apics, and
does things like vector allocation. The guest kernel is responsible for
asking for a vector, and doing the appropriate IO APIC programming, and
binding that vector to an event channel. The interrupt is then
delivered via the normal event channel mechanism already in place to
deal with all the other event types an unprivileged domain can get.
J
next prev parent reply other threads:[~2009-06-15 2:06 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-12 18:22 [PATCH RFC] x86/acpi: don't ignore I/O APICs just because there's no local APIC Jeremy Fitzhardinge
2009-06-12 18:22 ` Jeremy Fitzhardinge
2009-06-12 18:28 ` Alan Cox
2009-06-12 18:28 ` Alan Cox
2009-06-12 18:33 ` Jeremy Fitzhardinge
2009-06-12 18:33 ` Jeremy Fitzhardinge
2009-06-12 20:11 ` Cyrill Gorcunov
2009-06-15 2:01 ` Jeremy Fitzhardinge
2009-06-12 20:35 ` Eric W. Biederman
2009-06-12 20:35 ` Eric W. Biederman
2009-06-15 2:06 ` Jeremy Fitzhardinge [this message]
2009-06-15 10:47 ` Eric W. Biederman
2009-06-15 10:47 ` Eric W. Biederman
2009-06-15 20:49 ` Jeremy Fitzhardinge
2009-06-15 20:49 ` Jeremy Fitzhardinge
2009-06-15 21:58 ` Eric W. Biederman
2009-06-15 21:58 ` Eric W. Biederman
2009-06-16 19:38 ` Jeremy Fitzhardinge
2009-06-16 19:38 ` Jeremy Fitzhardinge
2009-06-17 5:10 ` Eric W. Biederman
2009-06-17 5:10 ` Eric W. Biederman
2009-06-17 12:02 ` Eric W. Biederman
2009-06-17 12:02 ` Eric W. Biederman
2009-06-17 17:32 ` Jeremy Fitzhardinge
2009-06-17 17:32 ` Jeremy Fitzhardinge
2009-06-18 2:58 ` Eric W. Biederman
2009-06-18 2:58 ` Eric W. Biederman
2009-06-18 19:34 ` Jeremy Fitzhardinge
2009-06-18 19:34 ` Jeremy Fitzhardinge
2009-06-18 20:28 ` Eric W. Biederman
2009-06-18 21:09 ` Jeremy Fitzhardinge
2009-06-18 21:09 ` Jeremy Fitzhardinge
2009-06-19 1:38 ` Eric W. Biederman
2009-06-19 1:38 ` Eric W. Biederman
2009-06-19 3:10 ` [Xen-devel] " Jiang, Yunhong
2009-06-19 3:10 ` Jiang, Yunhong
2009-06-18 12:26 ` Eric W. Biederman
2009-06-15 10:51 ` Eric W. Biederman
2009-06-15 10:51 ` Eric W. Biederman
2009-06-18 16:08 ` Len Brown
2009-06-18 19:14 ` Jeremy Fitzhardinge
2009-06-18 19:14 ` Jeremy Fitzhardinge
2009-06-18 19:27 ` Eric W. Biederman
2009-06-18 19:48 ` Jeremy Fitzhardinge
2009-06-18 19:48 ` Jeremy Fitzhardinge
2009-06-18 20:39 ` Eric W. Biederman
2009-06-18 22:33 ` Jeremy Fitzhardinge
2009-06-18 22:33 ` Jeremy Fitzhardinge
2009-06-19 2:42 ` Eric W. Biederman
2009-06-19 2:42 ` Eric W. Biederman
2009-06-19 19:58 ` Jeremy Fitzhardinge
2009-06-19 19:58 ` Jeremy Fitzhardinge
2009-06-19 23:44 ` [Xen-devel] " Nakajima, Jun
2009-06-19 23:44 ` Nakajima, Jun
2009-06-20 7:39 ` [Xen-devel] " Keir Fraser
2009-06-20 7:39 ` Keir Fraser
2009-06-20 8:21 ` [Xen-devel] " Eric W. Biederman
2009-06-20 8:21 ` Eric W. Biederman
2009-06-20 8:57 ` [Xen-devel] " Tian, Kevin
2009-06-20 8:57 ` Tian, Kevin
2009-06-20 10:22 ` [Xen-devel] " Keir Fraser
2009-06-20 10:22 ` Keir Fraser
2009-06-20 8:18 ` [Xen-devel] " Eric W. Biederman
2009-06-20 8:18 ` Eric W. Biederman
2009-06-19 5:32 ` Yinghai Lu
2009-06-19 5:32 ` Yinghai Lu
2009-06-19 5:50 ` Eric W. Biederman
2009-06-19 5:50 ` Eric W. Biederman
2009-06-19 7:52 ` [Xen-devel] Re: [PATCH RFC] x86/acpi: don't ignore I/O APICs justbecause " Jan Beulich
2009-06-19 7:52 ` Jan Beulich
2009-06-19 8:16 ` [Xen-devel] " Eric W. Biederman
2009-06-19 8:16 ` Eric W. Biederman
2009-06-20 3:58 ` [Xen-devel] " Yinghai Lu
2009-06-20 3:58 ` Yinghai Lu
2009-06-20 5:40 ` [Xen-devel] " Eric W. Biederman
2009-06-20 5:40 ` Eric W. Biederman
2009-06-20 5:58 ` [Xen-devel] " Yinghai Lu
2009-06-20 5:58 ` Yinghai Lu
2009-06-18 22:51 ` [PATCH RFC] x86/acpi: don't ignore I/O APICs just because " Maciej W. Rozycki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4A35ACB3.9040501@goop.org \
--to=jeremy@goop.org \
--cc=ebiederm@xmission.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=xen-devel@lists.xensource.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.