>Number:         11066
>Category:       port-alpha
>Synopsis:       machine check with IDE DMA restoring from ISA SCSI tape
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    port-alpha-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 21 23:30:00 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Simon Burge
>Release:        NetBSD-1.5_ALPHA2
>Organization:
Wasabi Systems
>Environment:
System: NetBSD thoreau.thistledown.com.au 1.5_ALPHA2 NetBSD 1.5_ALPHA2 (THOREAU)
#12: Wed Sep 20 16:50:13 EST 2000
simonb@thoreau.thistledown.com.au:/data/00/obj/sys/arch/alpha/compile/THOREAU alpha

>Description:
	I have an alpha PC164 with an IBM 46GB IDE disk, and an Exabyte
	8500 connected to a (ISA) Adaptec 1542B.  With ISA DMA enabled,
	restoring approx 1.2GB of data from tape results in a machine
	check, similar to:

		mces    = 0x1
		vector  = 0x660
		param   = 0xfffffc0000006060
		pc      = 0xfffffc0000300640
		ra      = 0xfffffc000036600c
		curproc = 0x0

	    panic: machine check

	The machine check has happened from 4 out of 4 attempts to
	restore data, each within about 500kB of 1.2GB of data.

	The PC and RA in the machine checks seem to be random.  For one,
	both the PC and RA were in pciide_dma_start, for another the
	PC was in idle and the RA in mi_switch, and another the PC in
	_pool_get and RA in wdc_get_xfer.  I don't have the PC and RA
	for the first machine check.

	Disabling DMA on the IDE disks (using flags 0x0ff0) stops
	the machine checks, as has switching to an NCR 53c810a SCSI
	controller for the Exabyte and leaving DMA enabled.

>How-To-Repeat:
	Restore approx 1.2GB of data from tape - works every time.
>Fix:
	None given.
>Release-Note:
>Audit-Trail:
>Unformatted: