Comment 1 for bug 258143

SRU Justification:

Impact: Some machines will not boot with ACPI enabled

Patch Description: Check that the root PCI bus has already been scanned.

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

Test Case: see bug desciption