i386/112596: aac driver causes kernel panic - page fault on 2xXeon 5050 with Multi-core features enabled (SMP kernel)

[Dmitriy Simakov]

>Number:         112596
>Category:       i386
>Synopsis:       aac driver causes kernel panic - page fault on 2xXeon 5050 with Multi-core features enabled (SMP kernel)
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri May 11 10:30:03 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Dmitriy Simakov
>Release:        FreeBSD 6.2-RELEASE
>Organization:
>Environment:
FreeBSD root.anews.ru 6.2-RELEASE-p4 FreeBSD 6.2-RELEASE-p4 #1: Tue May  1 13:37:01 MSD 2007     basilio at anews.ru:/usr/obj/usr/src/sys/SMP  i386

>Description:
Hardware:
Intel SR2500 server platform (S5000PAL chipset)
2x Dual-Core Xeon 5050 3.0Ghz
Adaptec SAS/SATA RAID 4805SAS

With Multi-Core enabled (by default), FreeBSD SMP kernel causes a panic - page fault right after detecting aac0 controller. GENERIC kernel works ok
>How-To-Repeat:
Enable Multi-Core capabilities in BIOS, install FreeBSD 6.2 (default options, SMP kernel) on aac-based raid5, try to boot system. I've got instant panic after aac0 initialisation.
>Fix:
1. Disable Multi-Core in BIOS. This also disables HyperThreading.
2. My coleague had similar problem with another Adaptec controller, also aac-based. Panic was not immediate, but regular. He swithced to amd64 kernel, and problem disappeared. 
>Release-Note:
>Audit-Trail:
>Unformatted: