I have a quad xeon piii-550 box ,it works on 4.11 SMP very well. now i "install" (not upgrade) 6.1-RC1 in this box. it works very well without SMP, but with SMP (with or with acpi) ,always PANIC,PANIC,PANIC... i got DDB stack trace, http://www.freebsd.org/cgi/query-pr.cgi?pr=96049 help me,please. yckuo