NetBSD 7.1 amd64 boot failure on KVM

["Andrei M." <lingvofactory%gmail.com@localhost>]

Hello all,

I've encountered a problem with running NetBSD 7.1 as guest on
KVM/qemu as experienced previously with 7.0:

https://mail-index.netbsd.org/netbsd-users/2015/12/31/msg017550.html

The output is practically the same, even the same values for registers:

vmt0 at cpu0: Unknown
vmware: open failed, eax=564d5868, ecx=0000001e, edx=00005658
vmt0: failed to open backdoor RPC channel (TCLO protocol)

Host machine - Linux Ubuntu 64 bit, qemu-kvm 1:2.5+dfsg-5ubunbtu10.14,
the guest machine (NetBSD 7.1) run through Virtual Machine Manager.
I've tried different memory values, between 512 MB and 1.5 GB (I
wasn't allowed to set more, even though my PC has 4GB), with the same
result.

The output refers to the following lines in NetBSD/sys/arch/x86/x86/vmt.c:

306 vmt_attach (device_t parent, device_t self, void *aux):
...
336 if (vm_rpc_open(&sc->sc_tclo_rpc, VM_RPC_OPEN_TCLO) != 0) {
337        aprint_error_dev(self, "failed to open backdoor RPC channel
(TCLO protocol)\n");
338        goto free;
339    }

http://bxr.su/NetBSD/sys/arch/x86/x86/vmt.c

Andrei