Re: ATA DMA broken/kernel panic with 5.1-R/5.1-C and VIA 82C586B

It seems Nicolai E M Plum wrote:
> Hi
> 
> I installed 5.1-RELEASE from the CD images, and have problems using DMA
> on my ATA discs. I get the same problem on several discs, both several
> years old and brand new, across several vendors. 4.6-RELEASE handles the
> discs fine. Relevant excepts from the boot messages are below, the
> entire thing can be seen at http://www.esperi.org/nicolai/misc/dmesg.eriador
> 
> FreeBSD 5.1-RELEASE #0: Thu Jun  5 02:55:42 GMT 2003
>     root_at_wv1u.btc.adaptec.com:/usr/obj/usr/src/sys/GENERIC
> ...
> atapci0: <VIA 82C586B UDMA33 controller> port 0xfcd0-0xfcdf mem 0xfbffe000-0xfbffffff at device 7.1 on pci0
> ata0: at 0x1f0 irq 14 on atapci0
> ata1: at 0x170 irq 15 on atapci0
> ...
> Timecounters tick every 10.000 msec
> ad0: 114473MB <ST3120022A> [232581/16/63] at ata0-master UDMA33
> ad0: READ command timeout tag=0 serv=0 - resetting
> ata0: resetting devices ..
> done
> ...     [ this repeats ]
> ad1: trying fallback to PIO mode
> ata0: resetting devices ..
> done
> Mounting root from ufs:/dev/ad0s1a
> 
> I noticed some ATA problems solved in -current recently, so I tried
> compiling a kernel from sources about 2 days ago. Booting from that
> (GENERIC) kernel, I do not get "Mounting root..", instead I get
> (approximately, can't cut/paste that console):
> 
> Fatal trap 12: page fault while in kernel mode
> fault virtual address	  = 0xdeadc0de
> fault code		  = supervisor read, page not present
> instruction pointer	  = 0x8:0xdeadcode
> stack pointer		  = 0x10:0xc736bc38
> frame pointer		  = 0x19:0xc736bc50
> ....
> current process		  = 21 (irc14: ata0)
> kernel: type 12 trap, code=0
> 
> Is this a known problem, perhaps specific to the 82C586B ATA controller?

This looks strange, I dont have semilar HW here to verify the problem
so I'm a bit in the dark. Is it possible you can build a kernel with
ddb in it so we can get a traceback of the panic ?

-Søren