Hello!

I don't have the relevant messages here, so I can't quote.

Kjetil speculated that my root and swap partitions overlap.
This can hardly be true, as the core dump being written to the swap partition
would then cause damage to the root partition, which does not happen.
It is quite sure that only the disklabel disappears, I have never observed any
damage to neither the Risc OS nor the RiscBSD partitions.

Scott asked me to supply disklabel. I should have done that in the first place.
Here it comes:
# /dev/rsd0c:
type: SCSI
disk: mysd
label: 
flags:
bytes/sector: 512
sectors/track: 96
tracks/cylinder: 6
sectors/cylinder: 576
cylinders: 3658
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# milliseconds
track-to-track seek: 0	# milliseconds
drivedata: 0 

5 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:    65664  1290816    4.2BSD     1024  8192    16 	# (Cyl. 2241 - 2354)
  b:    65664  1356480      swap                    	# (Cyl. 2355 - 2468)
  c:  2107008        0    unused        0     0       	# (Cyl.    0 - 3657)
  d:   816192        0    unused        0     0       	# (Cyl.    0 - 1416)
  e:   684864  1422144    4.2BSD     1024  8192    16 	# (Cyl. 2469 - 3657)