SRU: Hardy LP Bug #214814 - PCI/ACPI: "BUG: soft lockup - CPU#0 stuck for 61s!"

[Tim Gardner]

TJ wrote:
> This cherry-pick will fix the issue described in LP Bug #214814 "BUG:
> soft lockup - CPU#0 stuck for 61s!". The bug has previously been tagged
> for SRU but missed the 8.04.1 milestone. The upstream report is:
> 
> http://bugzilla.kernel.org/show_bug.cgi?id=10124
> 
> That patch has been tested and confirmed working.
> 
> ---
> commit b87e81e5c6e64ae0eae3b4f61bf07bfeec856184
> Author: yakui.zhao at intel.com <yakui.zhao at intel.com>
> Date:   Tue Apr 15 14:34:49 2008 -0700
> 
>     acpi: unneccessary to scan the PCI bus already scanned
> ---
> 
> Systems based on the Intel 450NX chipset may experience issues where
> devices aren't recognised that lead to drivers failing, unhandled IRQs,
> and other serious boot failures. The issue is caused because this
> chipset has 3 PCI root buses.
> When it was first released some operating systems (read: Windows NT)
> didn't always correctly discover the 2nd and 3rd PCI buses. As a result
> the PCI BIOS tables were 'hacked' to have a fake bridge device on PCI
> bus 0 that points to the same bus number as the 1st bus so they would be
> scanned correctly by the OS.
> 
> As a result, in a well-behaved OS the 2nd and 3rd PCI buses would be
> scanned twice. Once as secondaries of the 1st bus, and then as root
> buses in their own right. This caused problems with devices being
> discovered twice.
> 
> Unfortunately, the user's kernel-log report is misleading since the bus
> has already been found to be registered and therefore ignored. The
> situation can be worked around by booting with "pci=noacpi".
> 
> A fix-up for all i450N chipsets was introduced in
> arch/i386/pci/fixups.c::pci_fixup_i450nx(). Note: arch/i386 was
> refactored to arch/x86/ subsequently. The fix-up checks the PCI config
> for the subsidiary buses and if it finds them scans them. This adds them
> to the root_pci_bus list. Later in the boot process the ACPI/PCI code
> reads the ACPI DSDT table, finds the PCI bus entries (PNP0A03) and tries
> to scan them again, leading to the kernel BUG.
> 
> This patch ensures that buses already scanned are recognised rather than
> ignored.
> 
> TJ.
> Ubuntu Kernel ACPI Team.
> 
> 

Applied. LP: #258143

http://kernel.ubuntu.com/git?p=ubuntu/ubuntu-hardy.git;a=commit;h=4469fffe7db317faf023fa24fe87a900af0c3524

Note - I mistakenly created a new bug report, but I should have used the
existing #214814 (which I've now marked as a duplicate). Sigh, need to
postpone SRU processing in the morning until after I've had more coffee.
Thats twice this week.

-- 
Tim Gardner tim.gardner at ubuntu.com
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