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From: Vivek Goyal <vgoyal@redhat.com>
To: Don Zickus <dzickus@redhat.com>
Cc: x86@kernel.org, kexec-list <kexec@lists.infradead.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86, kdump: No need to disable ioapic in crash path
Date: Tue, 7 Feb 2012 17:19:24 -0500	[thread overview]
Message-ID: <20120207221924.GH6346@redhat.com> (raw)
In-Reply-To: <20120207215741.GD5650@redhat.com>

On Tue, Feb 07, 2012 at 04:57:41PM -0500, Don Zickus wrote:
> On Thu, Feb 02, 2012 at 03:24:46PM -0800, Eric W. Biederman wrote:
> > > Eric, brought up a point that because the boot code was restructured we may
> > > not need to disable the io apic any more in the crash path.  The original
> > > concern that led to the development of disable_IO_APIC, was that the TSC
> > > calibration on boot up relied on the PIT timer for reference.  Access
> > > to the PIT required 8259 interrupts to be working.  This wouldn't work
> > > if the ioapic needed to be configured.  So on panic path, the ioapic was
> > > reconfigured to use virtual wire mode to allow the 8259 to passthrough.
> > 
> > A small clarification originally it was the jiffies calibration that
> > would fail if we could cause the PIT to generate interrupts through the
> > 8259.  The boot would then hang at calibrating jiffies.
> 
> Ok.  Thanks!

So now what has changed? Do we setup LAPIC and IOAPIC early enough to
receive PIT interrupts in regular mode (non-virtual wire mode) or
something else?

Thanks
Vivek

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WARNING: multiple messages have this Message-ID (diff)
From: Vivek Goyal <vgoyal@redhat.com>
To: Don Zickus <dzickus@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
	kexec-list <kexec@lists.infradead.org>
Subject: Re: [PATCH] x86, kdump: No need to disable ioapic in crash path
Date: Tue, 7 Feb 2012 17:19:24 -0500	[thread overview]
Message-ID: <20120207221924.GH6346@redhat.com> (raw)
In-Reply-To: <20120207215741.GD5650@redhat.com>

On Tue, Feb 07, 2012 at 04:57:41PM -0500, Don Zickus wrote:
> On Thu, Feb 02, 2012 at 03:24:46PM -0800, Eric W. Biederman wrote:
> > > Eric, brought up a point that because the boot code was restructured we may
> > > not need to disable the io apic any more in the crash path.  The original
> > > concern that led to the development of disable_IO_APIC, was that the TSC
> > > calibration on boot up relied on the PIT timer for reference.  Access
> > > to the PIT required 8259 interrupts to be working.  This wouldn't work
> > > if the ioapic needed to be configured.  So on panic path, the ioapic was
> > > reconfigured to use virtual wire mode to allow the 8259 to passthrough.
> > 
> > A small clarification originally it was the jiffies calibration that
> > would fail if we could cause the PIT to generate interrupts through the
> > 8259.  The boot would then hang at calibrating jiffies.
> 
> Ok.  Thanks!

So now what has changed? Do we setup LAPIC and IOAPIC early enough to
receive PIT interrupts in regular mode (non-virtual wire mode) or
something else?

Thanks
Vivek

  reply	other threads:[~2012-02-07 23:17 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-02 18:12 [PATCH] x86, kdump: No need to disable ioapic in crash path Don Zickus
2012-02-02 18:12 ` Don Zickus
2012-02-02 23:24 ` Eric W. Biederman
2012-02-02 23:24   ` Eric W. Biederman
2012-02-07 21:57   ` Don Zickus
2012-02-07 21:57     ` Don Zickus
2012-02-07 22:19     ` Vivek Goyal [this message]
2012-02-07 22:19       ` Vivek Goyal
2012-02-07 23:35       ` Eric W. Biederman
2012-02-07 23:35         ` Eric W. Biederman
2012-02-08 20:11         ` Don Zickus
2012-02-08 20:11           ` Don Zickus
2012-02-08 22:55           ` Eric W. Biederman
2012-02-08 22:55             ` Eric W. Biederman
2012-02-09 14:48             ` Don Zickus
2012-02-09 14:48               ` Don Zickus
  -- strict thread matches above, loose matches on Subject: below --
2012-02-29 20:08 Don Zickus
2012-02-29 20:08 ` Don Zickus
2012-03-15 20:26 ` Don Zickus
2012-03-15 20:26   ` Don Zickus
2012-03-15 21:16   ` Seiji Aguchi
2012-03-15 21:16     ` Seiji Aguchi
2012-03-15 21:33     ` Don Zickus
2012-03-15 21:33       ` Don Zickus
2012-03-15 21:37       ` Seiji Aguchi
2012-03-15 21:37         ` Seiji Aguchi
2012-04-30 20:53     ` Don Zickus
2012-04-30 20:53       ` Don Zickus
2012-05-02 19:10       ` Seiji Aguchi
2012-05-02 19:10         ` Seiji Aguchi
2012-05-02 19:39         ` Eric W. Biederman
2012-05-02 19:39           ` Eric W. Biederman
2012-05-02 19:59           ` Don Zickus
2012-05-02 19:59             ` Don Zickus
2012-05-02 20:24             ` Eric W. Biederman
2012-05-02 20:24               ` Eric W. Biederman
2012-03-29 16:02 ` Don Zickus
2012-03-29 16:02   ` Don Zickus

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