panic: trap type 6, code=10, pc=0
Starting stack trace...
panic(ffffffff82791975) at panic+0x16f sys/kern/subr_prf.c:229
kerntrap(ffff80002e41d120) at kerntrap+0x1d7 sys/arch/amd64/amd64/trap.c:327
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
0(fffffd80660c2f00,fffffd80660c2f00,0,fffffd80660c2f00,53f,0) at 0
softclock_process_kclock_timeout(fffffd80660c2f00,0) at softclock_process_kclock_timeout+0x1ca sys/kern/kern_timeout.c:665
softclock(0) at softclock+0x11a sys/kern/kern_timeout.c:716
softintr_dispatch(0) at softintr_dispatch+0xfb sys/arch/amd64/amd64/softintr.c:90
Xsoftclock() at Xsoftclock+0x27
__sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+0x29 kd_curproc sys/dev/kcov.c:589 [inline]
__sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+0x29 sys/dev/kcov.c:158
_rb_parent(ffffffff829ee908,fffffd8069b10e20) at _rb_parent+0x27 rb_n2e sys/kern/subr_tree.c:51 [inline]
_rb_parent(ffffffff829ee908,fffffd8069b10e20) at _rb_parent+0x27 sys/kern/subr_tree.c:589
uvm_mapent_free_insert(fffffd8008a06000,fffffd807f7d4948,fffffd8069b10e20) at uvm_mapent_free_insert+0x1e2 uvm_map_addr_augment sys/uvm/uvm_map.c:704 [inline]
uvm_mapent_free_insert(fffffd8008a06000,fffffd807f7d4948,fffffd8069b10e20) at uvm_mapent_free_insert+0x1e2 sys/uvm/uvm_map.c:378
uvm_map_fix_space(fffffd8008a06000,fffffd8069b10e20,d7b3be7000,79726d064000,80713) at uvm_map_fix_space+0x415 sys/uvm/uvm_map.c:5172
uvm_map_mkentry(fffffd8008a06000,fffffd806ba0e408,fffffd806ba0e408,d7b3be4000,3000,80713,586d048769788d24,d7b3be4000) at uvm_map_mkentry+0x2e2 sys/uvm/uvm_map.c:1500
uvm_mapanon(fffffd8008a06000,ffff80002e41d7a8,3000,1000,80713) at uvm_mapanon+0x61e sys/uvm/uvm_map.c:859
sys_mmap(ffff800021234020,ffff80002e41d850,ffff80002e41d8a0) at sys_mmap+0x870 uvm_mmapanon sys/uvm/uvm_mmap.c:1007 [inline]
sys_mmap(ffff800021234020,ffff80002e41d850,ffff80002e41d8a0) at sys_mmap+0x870 sys/uvm/uvm_mmap.c:421
syscall(ffff80002e41d920) at syscall+0x606 mi_syscall sys/sys/syscall_mi.h:110 [inline]
syscall(ffff80002e41d920) at syscall+0x606 sys/arch/amd64/amd64/trap.c:623
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x79726f163560, count: 240
End of stack trace.

dump to dev 4,1 not possible
rpeabnoioct:i knegr.ne.l. 
diagnostic asserSeaBIOS (version 1.8.2-google)
Total RAM Size = 0x0000000080000000 = 2048 MiB
CPUs found: 2     Max CPUs supported: 2
SeaBIOS (version 1.8.2-google)
Machine UUID 5539092a-1476-82b6-0a34-88b96a0f4c53
found virtio-scsi at 0:3
virtio-scsi vendor='Google' product='PersistentDisk' rev='1' type=0 removable=0
virtio-scsi blksize=512 sectors=4194304 = 2048 MiB
drive 0x000f2850: PCHS=0/0/0 translation=lba LCHS=520/128/63 s=4194304
Sending Seabios boot VM event.
Booting from Hard Disk 0...
>> OpenBSD/amd64 BOOT 3.56
boot> set $lines = 0
set: syntax error
boot> set $maxwidth = 0
set: syntax error
boot> show panic
boot: illegal argument panic
boot> trace
boot> show registers
boot> show proc
boot> ps
boot> show all locks
boot> show malloc
boot> show all pools
boot> machine ddbcpu 0
machine: syntax error
boot> trace
boot> machine ddbcpu 1
machine: syntax error
boot> trace