We have 3 of the 32 port Comtrol PCI cards, the original 5v only cards, not the newer universal PCI cards, and we are trying to upgrade the system with all these serial ports from FreeBSD 4.8 (ya, kinda old) to FreeBSD 6.2. And we are running into what seems like a common problem with these cards: panics about non-busy devices: panic: device_unbusy: called for non-busy device rp0 The PR kern/109152 addresses this issue, and the patch from Craig Leres added to the PR on Tue, 13 Mar 2007 19:27:01 -0700 solves the problems for me. (I was experiencing the problems with HylaFAX, but it seems easy to reproduce.) Can this patch be applied to RELENG_6? I've also tried the patch from John Baldwin posed to freebsd-hackers in http://groups.google.com/group/mailing.freebsd.hackers/browse_frm/thread/883da63a8c62854d that generates a rp_open_count for each device with out any change in the behavior, I would continue to panic the system by sending a FAX.