PE1950, PERC 5/i, pci=assign-busses

[Matt Domsch]

On Mon, Sep 29, 2008 at 04:57:23PM -0700, Layne Miller wrote:
>    I have a PowerEdge 1950 running CentOS 5.2.  It is configured with a PERC
>    5/i controller, and also has a PCI-X adapter which seems to require the
>    pci=assign-busses option.  Whenever I enable the pci=assign-busses boot
>    option, the system is unable to boot -- it hangs apparently while
>    initializing the storage.

pci=assign-busses should never be needed on a Dell server.  The BIOS
intentionally reserves sufficient bus numbers for each slot such that
even hot-plug PCI should work (though in practice it's rarely used).
I know the kernel may suggest such.  pci=assign-busses does so behind
the back of the BIOS and its ACPI interrupt routing information, as
well as other aspects which expect the running configuration to have
been specified by BIOS and not re-written by the OS.

>    Loading megaraid_sas.ko module
>    megasas: 00.00.03.15-RH1 Wed Nov. 21 10:29:45 PST 2007
>    megasas: 0x1028:0x0015:0x1028:0x1f03: bus 8:slot 14:func 0
>    ACPI: PCI Interrupt 0000:08:0e.0[A] -> GSI 78 (level, low) -> IRQ 82
>    megasas: FW now in Ready state
>    scsi0 : LSI SAS based MegaRAID driver
> 
>    ... hangs here for several minutes ...
> 
>    scsi 0:0:0:0: megasas: RESET -1 cmd=12 retries=0
>    megasas: [ 0]waiting for 1 commands to complete
>    megasas: [ 5]waiting for 1 commands to complete
>    megasas: [10]waiting for 1 commands to complete
>    megasas: [15]waiting for 1 commands to complete
>    megasas: [20]waiting for 1 commands to complete
>    megasas: [25]waiting for 1 commands to complete
>    megasas: [30]waiting for 1 commands to complete
>    ...
> 
>    This behavior occurs whether I have the PCI-X adapter installed or not.
>    Is this a known problem, and is there a workaround?

This would indicate that the interrupts assigned for the megasas
controller are incorrect, due to pci=assign-busses.

Do you know the PCI bus structure of your extra PCI-X adapter?  How
many bridges and busses does it have?  2, 4, or more?  Is it a
Dell-supported card?  What is the behavior when the PCI-X adapter is
present but you don't use pci=assign-busses?

I would recommend filing a formal issue with Dell Tech Support about
this.

-- 
Matt Domsch
Linux Technology Strategist, Dell Office of the CTO
linux.dell.com & www.dell.com/linux