From: Gleb Natapov <gleb@redhat.com>
To: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Vivek Goyal <vgoyal@redhat.com>,
linux-kernel@vger.kernel.org,
Suresh Siddha <suresh.b.siddha@intel.com>,
Sheng Yang <sheng@linux.intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"avi@redhat.com" <avi@redhat.com>
Subject: Re: [PATCH v4] enable x2APIC without interrupt remapping under KVM
Date: Tue, 30 Jun 2009 21:53:48 +0300 [thread overview]
Message-ID: <20090630185347.GD8122@redhat.com> (raw)
In-Reply-To: <86802c440906301143s14d0cc9ej9b666271a1ce15ba@mail.gmail.com>
On Tue, Jun 30, 2009 at 11:43:41AM -0700, Yinghai Lu wrote:
> 2009/6/30 Gleb Natapov <gleb@redhat.com>:
>
> >>
> >> how about kexec second kernel in KVM ?
> >>
> >> x2apic_preenabled will be set in second kernel.
> >>
> > Yes, bummer. But the similar problem exist now and without KVM. After
> > running x2apic enabled kernel you can't kexec kernel without x2apic
> > support.
>
> if the first kernel enable x2apic and intr_remapping, and second
> kernel has x2apic and intr_remap support.
> we can kexec the second kernel.
>
And if it hasn't we cannot, that is what I am trying to point out.
> restoring to original state is not possible for kdump case.
>
Shouldn't it be enough to run UP kernel for kdump? So kdump can reset BSP
apic to xAPIC mode before starting a kernel with maxcpus=1.
> maybe with minor change to your patch, you could kexec the in kexec
> second kernel with x2apic support.
>
My patch can easily avoid the issue by checking max_physical_apicid > 255
instead of x2apic_preenabled.
--
Gleb.
next prev parent reply other threads:[~2009-06-30 18:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-30 6:45 [PATCH v4] enable x2APIC without interrupt remapping under KVM Gleb Natapov
2009-06-30 7:18 ` Yinghai Lu
2009-06-30 7:54 ` Gleb Natapov
2009-06-30 18:43 ` Yinghai Lu
2009-06-30 18:53 ` Gleb Natapov [this message]
2009-06-30 15:58 ` Gleb Natapov
2009-06-30 17:00 ` Eric W. Biederman
2009-06-30 17:14 ` Avi Kivity
2009-06-30 19:24 ` Eric W. Biederman
2009-06-30 19:15 ` Gleb Natapov
2009-06-30 17:15 ` Eric W. Biederman
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=20090630185347.GD8122@redhat.com \
--to=gleb@redhat.com \
--cc=avi@redhat.com \
--cc=ebiederm@xmission.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=sheng@linux.intel.com \
--cc=suresh.b.siddha@intel.com \
--cc=vgoyal@redhat.com \
--cc=yhlu.kernel@gmail.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.