reading /dev/mem panics a domU

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

Hi

I just discovered the oddity below, on a netbsd-5 domU. Is there a
reason for not calling that a bug? Does it happens only at mine?

# strings /dev/mem > /dev/null
xpq_flush_queue: 1 entries 
0x00000000a8b5e948: 0x0000000000000221
panic: HYPERVISOR_mmu_update failed

fatal breakpoint trap in supervisor mode
trap type 1 code 0 eip c03a829c cs 9 eflags 246 cr2 bbbb2538 ilevel 6
Stopped in pid 534.1 (strings) at       netbsd:breakpoint+0x4:  popl
%ebp
db> bt
breakpoint(c045b777,cb89aa78,c0470d80,c03123a5,0,5,0,0,cb89aa88,0) at
netbsd:breakpoint+0x4
panic(c045d0aa,a8b5e948,0,221,0,ca1fe468,0,c02ac0f1,ca206854,0) at
netbsd:panic+0x1a6
xpq_flush_queue(a8b5e948,221,0,c03b0e48,ca2196c0,ffffffff,1,221,0,0) at
netbsd:xpq_flush_queue+0xb3
pmap_enter_ma(c04f16a0,c0652000,0,0,1,11,7ff0,0,0,cb89ac7c) at
netbsd:pmap_enter_ma+0x3e1
pmap_enter(c04f16a0,c0652000,0,1,11,cb89ac7c,cb89ab7c,c03080ba,1,0) at
netbsd:pmap_enter+0x73
mmrw(200,cb89ac7c,0,cb2c33a4,cb89abb4,ca206854,cb89ac2c,c0352c74,cb2c344
4,cb2c33a4) at netbsd:mmrw+0x148
spec_read(cb89ac08,1,cb89ac1c,c035e208,cb2c33a4,c041d360,cb2c33a4,cb89ac
7c,0,ca206854) at netbsd:spec_read+0x22d
VOP_READ(cb2c33a4,cb89ac7c,0,ca206854,3,cb89ac70,402c,16,8000,bb907000)
at netbsd:VOP_READ+0x31
vn_read(cb6e6484,cb6e6484,cb89ac7c,ca206854,1,0,0,0,0,0) at
netbsd:vn_read+0x98
dofileread(3,cb6e6484,bb907000,8000,cb6e6484,1,cb89ad28,cb866a00,cb866a0
0,0) at netbsd:dofileread+0x73
sys_read(cb866a00,cb89ad00,cb89ad28,bbbb2538,bbbb2000,cb812b9c,1,3,bb907
000,8000) at netbsd:sys_read+0x6f
syscall(cb89ad48,1f,1f,1f,1f,bbb74900,bbb74900,bfbfe5a8,bbb692d4,0) at
netbsd:syscall+0xc7
-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost