From: Vivek Goyal <vgoyal@redhat.com>
To: Neil Horman <nhorman@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>,
Ben Woodard <woodard@redhat.com>,
Andi Kleen <andi@firstfloor.org>,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
Andi Kleen <ak@suse.de>,
hbabu@us.ibm.com, "Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu
Date: Fri, 7 Dec 2007 09:39:44 -0500 [thread overview]
Message-ID: <20071207143944.GF2863@redhat.com> (raw)
In-Reply-To: <20071207001023.GA7312@hmsendeavour.rdu.redhat.com>
On Thu, Dec 06, 2007 at 07:10:23PM -0500, Neil Horman wrote:
> On Thu, Dec 06, 2007 at 05:11:43PM -0500, Vivek Goyal wrote:
> > On Thu, Dec 06, 2007 at 04:39:51PM -0500, Neil Horman wrote:
> > > On Fri, Nov 30, 2007 at 09:51:31AM -0500, Neil Horman wrote:
> > > > On Fri, Nov 30, 2007 at 09:42:50AM -0500, Vivek Goyal wrote:
> > > <snip>
> > > >
> > > > Thats what I'm doing at the moment. I'm working on a RHEL5 patch at the moment
> > > > (since thats whats on the production system thats failing), and will forward
> > > > port it once its working
> > > >
> > > > And not to split hairs, but techically thats not our _only_ choice. We could
> > > > force kdump boots on cpu0 as well ;)
> > > >
> > > > Thanks
> > > > Neil
> > > >
> > > > > Thanks
> > > > > Vivek
> > > >
> > >
> > >
> > > Sorry to have been quiet on this issue for a few days. Interesting news to
> > > report, though. So I was working on a patch to do early apic enabling on
> > > x86_64, and had something working for the old 2.6.18 kernel that we were
> > > origionally testing on. Unfortunately while it worked on 2.6.18 it failed
> > > miserably on 2.6.24-rc3-mm2, causing check_timer to consistently report that the
> > > timer interrupt wasn't getting received (even though we could successfully run
> > > calibrate_delay). Vivek and I were digging into this, when I ran accross the
> > > description of the hypertransport configuration register in the opteron
> > > specification. It contains a bit that, suprise, configures the ht bus to either
> > > unicast interrupts delivered accross the ht bus to a single cpu, or to broadcast
> > > it to all cpus. Since it seemed more likely that the 8259 in the nvidia
> > > southbridge was transporting legacy mode interrupts over the ht bus than
> > > directly to cpu0 via an actual wire, I wrote the attached patch to add a quirk
> > > for nvidia chipsets, which scanned for hypertransport controllers, and ensured
> > > that that broadcast bit was set. Test results indicate that this solves the
> > > problem, and kdump kernels boot just fine on the affected system.
> > >
> >
> > Hi Neil,
> >
> > Should we disable this broadcasting feature once we are through? Otherwise
> > in normal systems it might mean extra traffic on hypertransport. There
> > is no need for every interrupt to be broadcasted in normal systems?
> >
> > Thanks
> > Vivek
>
> No, I don't think thats necessecary. Once the apics are enabled, interrupts
> shouldn't travel accross the hypertransport bus anyway, opting instead to use
> the dedicated apic bus (at least thats my understanding).
I think all interrupt message travel on hypertransport. Even after APICS
have been enabled.
Look at the following document.
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/24674.pdf
Have a look at figure 1, figure 2 and section 3.4.2.2 and 3.4.2.3
That's a different thing that once IOAPIC has formed the vectored message,
Hypertransport might not touch the destination field.
Having said that, I am wondering what will happen if a system continues
to operate the timer through IOAPIC in ExtInt mode. Will hypertransport
keep on broadcasting that interrupt to every cpu? And every cpu will
process that interrupt.
Hence, I feel it is safe to restore the broadcast bit back to BIOS value once
we are through calibrate_delay().
Thanks
Vivek
next prev parent reply other threads:[~2007-12-07 14:49 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-27 1:47 [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu Neil Horman
2007-11-27 4:12 ` Eric W. Biederman
2007-11-27 13:13 ` Neil Horman
2007-11-27 13:28 ` Eric W. Biederman
2007-11-27 13:45 ` Andi Kleen
2007-11-27 14:28 ` Neil Horman
2007-11-27 14:43 ` Andi Kleen
2007-11-27 14:48 ` Neil Horman
2007-11-27 15:24 ` Andi Kleen
2007-11-27 15:30 ` Eric W. Biederman
2007-11-27 16:45 ` Neil Horman
2007-11-27 20:50 ` Ben Woodard
2007-11-27 21:05 ` Neil Horman
2007-11-27 22:38 ` Eric W. Biederman
2007-11-27 23:15 ` Ben Woodard
2007-11-28 0:15 ` Eric W. Biederman
2007-11-27 23:40 ` Neil Horman
2007-11-28 0:43 ` Eric W. Biederman
2007-11-28 15:54 ` Neil Horman
2007-11-27 14:56 ` Eric W. Biederman
2007-11-27 15:34 ` Neil Horman
2007-11-27 18:41 ` Ben Woodard
2007-11-27 19:42 ` Neil Horman
2007-11-27 20:00 ` Vivek Goyal
2007-11-27 20:52 ` Neil Horman
2007-11-27 22:24 ` Andi Kleen
2007-11-27 23:24 ` Ben Woodard
2007-11-27 23:56 ` Andi Kleen
2007-11-28 15:36 ` Vivek Goyal
2007-11-28 16:02 ` Neil Horman
2007-11-28 17:36 ` Eric W. Biederman
2007-11-28 18:16 ` Neil Horman
2007-11-28 19:05 ` Vivek Goyal
2007-11-28 19:42 ` Eric W. Biederman
2007-11-28 21:09 ` Neil Horman
2007-11-28 23:27 ` Eric W. Biederman
2007-11-30 2:16 ` Ben Woodard
2007-11-30 2:54 ` Eric W. Biederman
2007-11-30 8:59 ` Yinghai Lu
2007-11-30 14:35 ` Vivek Goyal
2007-11-30 14:32 ` Neil Horman
2007-11-30 2:12 ` Ben Woodard
2007-11-30 14:42 ` Vivek Goyal
2007-11-30 14:51 ` Neil Horman
2007-12-06 21:39 ` Neil Horman
2007-12-06 22:11 ` Vivek Goyal
2007-12-07 0:10 ` Neil Horman
2007-12-07 14:39 ` Vivek Goyal [this message]
2007-12-07 14:53 ` Neil Horman
2007-12-07 15:16 ` Vivek Goyal
2007-12-07 15:53 ` Neil Horman
2007-12-07 18:46 ` Eric W. Biederman
2007-12-07 0:33 ` Eric W. Biederman
2007-12-07 2:04 ` Neil Horman
2007-12-07 8:50 ` Yinghai Lu
2007-12-07 9:22 ` Yinghai Lu
2007-12-07 14:21 ` Neil Horman
2007-12-07 17:58 ` Neil Horman
2007-12-07 19:19 ` yhlu
2007-12-07 20:13 ` Neil Horman
2007-12-10 15:39 ` Neil Horman
2007-12-10 16:20 ` Vivek Goyal
2007-12-11 1:17 ` Eric W. Biederman
2007-12-11 1:08 ` Eric W. Biederman
2007-12-11 3:43 ` Neil Horman
2007-12-11 4:48 ` Eric W. Biederman
2007-12-11 6:31 ` Yinghai Lu
2007-12-11 14:39 ` Neil Horman
2007-12-11 15:29 ` Eric W. Biederman
2007-12-11 18:00 ` Yinghai Lu
2007-12-11 18:29 ` Neil Horman
2007-12-11 18:45 ` Yinghai Lu
2007-12-11 18:22 ` Neil Horman
2007-12-11 18:46 ` Eric W. Biederman
2007-12-11 19:24 ` Neil Horman
2007-12-11 19:51 ` Yinghai Lu
2007-12-11 20:59 ` Neil Horman
2007-12-12 0:16 ` Ben Woodard
2007-12-12 0:52 ` Neil Horman
2007-12-12 1:07 ` Yinghai Lu
2007-12-12 8:43 ` [PATCH] k8: Enable legacy irqs with extended cpu ids Eric W. Biederman
2007-12-12 14:21 ` [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu Andi Kleen
2007-12-12 15:55 ` Neil Horman
2007-12-12 16:07 ` Andi Kleen
2007-12-12 19:43 ` Eric W. Biederman
2007-12-12 20:22 ` Neil Horman
2007-12-12 21:32 ` Eric W. Biederman
2007-12-13 14:39 ` Neil Horman
2007-12-13 15:16 ` Andi Kleen
2007-12-13 15:32 ` Neil Horman
2007-12-17 11:38 ` Neil Horman
2007-12-18 0:13 ` Eric W. Biederman
2007-12-17 15:16 ` Ingo Molnar
2007-12-17 15:47 ` Neil Horman
2007-12-07 18:36 ` Eric W. Biederman
2007-12-07 18:48 ` Neil Horman
2007-11-27 13:53 ` Neil Horman
2007-11-27 10:55 ` Andi Kleen
2007-11-27 11:19 ` Eric W. Biederman
2007-11-27 13:28 ` Neil Horman
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