Re: [Qemu-discuss] emulate 64-bit app in 32-bit linux

[Peter Maydell]

On 21 December 2017 at 16:36, Thomas Schmiedl <address@hidden> wrote:
> I try to emulate this Intel 64-bit app
> https://drive.google.com/open?id=0B-F25LE4in_xYjMwME1BODRpdFU (from
> http://xupnpd.org/) on 32-bit Intel hardware (Ubuntu 16.04.1 LTS) using
> qemu-x86_64 from git, version 2.11.50 (v2.11.0-303-g4da5c51-dirty).

In general emulating a 64-bit guest application on a 32-bit host
with the linux-user qemu won't work (it may work some of the
time or for simple programs). 32-on-32, 64-on-64 and 32-on-64
are the only really supported combinations. That said...

> I extracted the required 64-bit libs from
> http://archive.ubuntu.com/ubuntu/dists/xenial/main/installer-amd64/current/images/netboot/mini.iso.
>
> The command "qemu-x86_64 xupnpd" returned this error:
> xupnpd-2.0-17.238.2143-beta
> Copyright (C) 2015-2017 Anton Burdinuk <address@hidden>
> All rights reserved
> Proprietary software
>
> ssdp interface: lo, address: 127.0.0.1
> Unsupported setsockopt level=0 optname=32
> unable to create multicast outgoing socket for ssdp exchange
> bye.

...this is setsockopt SOL_IP IP_MULTICAST_IF, which is an
option type QEMU doesn't support yet, so this particular
guest program wouldn't work even if emulated 64-on-64.

I agree with Nerijus, though: the source for xupnpd is
available, so you'll be much better off just building it
for 32-bit x86. It will run at least 10 times faster that
way than trying to run the 64-bit binary under QEMU, and
it looks like it's the sort of program where performance
matters for video playback.

thanks
-- PMM