This is my situation before 2.6.20-11.
With pci=nomsi and acpi=off no problems
Without pci=nomsi the disk is not recognised
Without acpi=off kernel panic.
pci=nommconf has no benefit
After the upgrade to 2.6.20-11 i can boot, with no problems, without the pci=nomsi option (still remains the kernel panic with no acpi=off).
It looks like the bug got fixed.
This is my situation before 2.6.20-11.
With pci=nomsi and acpi=off no problems
Without pci=nomsi the disk is not recognised
Without acpi=off kernel panic.
pci=nommconf has no benefit
After the upgrade to 2.6.20-11 i can boot, with no problems, without the pci=nomsi option (still remains the kernel panic with no acpi=off).
It looks like the bug got fixed.