this is odd...

the machine in question is an ultra5 with an ide disk and a
scsi disk on a symbios logic 53c860 that i picked up at a
local hardware store. the disk layout is as follows:

Filesystem  1K-blocks     Used     Avail Capacity  Mounted on
/dev/wd0a      127175    29937     90879    24%    /
/dev/wd0d     1014221    55353    908156     5%    /var
/dev/wd0g     5988356   234833   5454105     4%    /usr
mfs:109          7911        1      7514     0%    /tmp
/dev/sd0a     4061755  1259337   2599330    32%    /src
/dev/sd0b     4061755       10   3858657     0%    /home
/dev/sd0g     1015318   157670    806882    16%    /sparc32

i did something that caused a kernel panic (an apparently
repeatable problem relating to sparc32 emulation and 
chroot). when savecore runs upon a reboot, the ide controller
gets confused:

pciide0:0:0: lost interrupt
        type: ata tc_bcount: 65536 tc_skip: 0
pciide0:0:0: bus-master DMA error: status=0x22
pciide0:0:0: bus-master DMA error: missing interrupt, status=0x22

and a disk operation fails recoverably:

wd0: transfer error, downgrading to PIO mode 4
wd0(pciide0:0:0): using PIO mode 4
wd0b: DMA error reading fsbn 1834496 of 1834496-1834623 (wd0 bn 2097584; cn 2080
 tn 14 sn 62), retrying
wd0: soft error (corrected)

a little later in the boot sequence, when an attempt is made to mount /dev/sd0a,
the scsi controller resets and does not recover:

DMA IRQ: Illegal instruction dma fifo empty, DSP=0x6cca8 DSA=0xffffffff: siop0: 
current DSA invalid
siop0: scsi bus reset
sd0(siop0:0:6:0): command with tag id 1 reset

i have only seen this behaviour when savecore runs, never in any
other circumstance.

.w.