Re: IO-APIC on nforce2 [PATCH] + [PATCH] for nmi_debug=1 + [PATCH] for idle=C1halt, 2.6.5

From: Arjen Verweij (A.Verweij2_at_ewi.tudelft.nl)
Date: 04/15/04

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    Date:	Thu, 15 Apr 2004 23:56:09 +0200 (METDST)
To: Len Brown <len.brown@intel.com>

    On 15 Apr 2004, Len Brown wrote:

    > On Thu, 2004-04-15 at 11:10, Ross Dickson wrote:
    > > On Wednesday 14 April 2004 11:02, Len Brown wrote:
    > > > Re: IRQ0 XT-PIC timer issue
    > > >
    > > > Since the hardware is connected to APIC pin0, it is a BIOS bug
    > > > that an ACPI interrupt source override from pin2 to IRQ0 exists.
    > > >
    > > > With this simple 2.6.5 patch you can specify "acpi_skip_timer_override"
    > > > to ignore that bogus BIOS directive. The result is with your
    > > > ACPI-enabled APIC-enabled kernel, you'll get IRQ0 IO-APIC-edge timer.
    > > >
    > > > Probably there is a more clever way to trigger this workaround
    > > > automatcially instead of via boot parameter.
    >
    > > Hi Len, I have updated my nforce2 patches for 2.6.5 to work with your patch.
    > > I have tested them only on one nforce2 board Epox 8Rga+ but as little has
    > > changed in core functionality from past releases I think all will be OK....
    > > Hopefully no clock skew. I saw none on my system but thats no guarantee.
    >
    > While I don't want to get into the business of maintaining
    > a dmi_scan entry for every system with this issue, I think
    > it might be a good idea to add a couple of example entries
    > for high volume systems for which there is no BIOS fix available.
    >
    > Got any opinions on which system to use as the example?
    > I'll need the output from dmidecode for them.
    >
    > > I tried your above patch with the timer_ack on as is default in 2.6.5 and
    > > nmi_watchdog=1 failed as expected. I still think Maciej's 8259 ack patch
    > > is more complete solution to the ack issue but this one gets watchdog going for
    > > nforce2. I cannot see anyone using your above patch without an integrated
    > > apic and tsc so I cannot see a problem triggering it off your kern arg.
    >
    > "acpi_skip_timer_override" is specific to IOAPIC mode,
    > since that is the only place that the bogus interrupt
    > source override is used.
    >
    > I'm not clued-in on the nmi_watchdog and 8259 ack issues.
    > My focus is primarily the ACPI issues involved in getting
    > these systems up and running in IOAPIC mode.
    >
    > > The second patch is the C1halt update I suggested in another posting.
    > > http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-04/1707.html
    >
    > Clearly this hang issue is more important than the timer issue.
    > I'm impressed that you built such a sophisticated patch without
    > any support from the vendors. But it would be a "really good thing"
    > if we got some input from the vendors before considering putting
    > a workaround into the upstream kernel -- for they may have
    > guidance which would either simplify it, or make it unnecessary.
    > Perhaps Allen Martin at nVidia can comment?

    Yes, this sounds like a marvellous idea, since every board except some
    Shuttle board after a BIOS update does not suffer from these hangs.
    Unfortunately, Allen Martin already commented on this once:

    "Likely the root of the problem has to do with the way the Linux kernel is
    using the ACPI methods to setup the interrupts which is different from win
    9x/2k/XP. I can help track this down, unfortunately so far I've been
    unable to reproduce the hangs on any of the boards I have."
    -Allen

    http://lkml.org/lkml/2003/12/5/156

    Maybe he can find useful hints on how to crash his box with an nforce2
    chipset here:

    http://atlas.et.tudelft.nl/verwei90/nforce2/

    Basically just enable APIC in the kernel and start pushing the HDD or
    anything related to I/O really. The crashes come more regularely in 2.6
    kernels because of the increased Hz value.

    Regards,

    Arjen

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