Re: Bug with Windows tap network when running qemu-system-ppc with Mac OS 9 guest

[Howard Spoelstra]

On Fri, Mar 26, 2021 at 2:50 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> Hi Howard,
>
> On Fri, Mar 26, 2021 at 1:35 AM Peter Maydell <peter.maydell@linaro.org> 
> wrote:
> >
> > (adding the relevant people to the cc list)
> >
> > On Thu, 25 Mar 2021 at 17:26, Howard Spoelstra <hsp.cat7@gmail.com> wrote:
> > >
> > > Hi,
> > >
> > > When running qemu-system-ppc with Mac OS guest, the guest crashes when
> > > using a tap network connection. Openvpn 2.4.9-I601-win10 is installed
> > > with TAP-Windows 9.24.2. A tap connection called TapQemu is bridged
> > > with the default ethernet connection. It gets activated when I start
> > > qemu.
> > >
> > > To reproduce, compile qemu-system-ppc from current source and run:
> > >
> > > qemu-system-ppc.exe ^
> > > -L pc-bios ^
> > > -M mac99 ^
> > > -m 128 ^
> > > -sdl -serial stdio ^
> > > -boot c ^
> > > -drive file=C:\Mac-disks\9.2.img,format=raw,media=disk ^
> > > -device sungem,netdev=network01 -netdev tap,ifname=TapQemu,id=network01
> > >
> > > I bisected to the commit below. Thanks for looking into this.
>
> Thanks for reporting.
>
> Can you please provide some further information:
>
> 1. Does "-net user" work on Windows?
> 2. If running QEMU under Linux, does "-net tap" or "-net user" work?
>
> Regards,
> Bin

Hello Bin,

Thanks for getting back to me. I forgot to mention that reverting the
above patch restores functionality. And that other applications using
the same tap device work correctly.
In answer to your questions:

1. Yes, slirp works on Windows 10 with this setup.
2. Yes, in Linux both tap and slirp work.

My Windows build is done with a fully up to date msys2 installation.

I tried to debug in Windows:
(gdb) run
Starting program: c:\qemu-master-msys2\qemu-system-ppc.exe -L pc-bios
-M mac99 -m 128 -sdl -serial stdio -boot c -drive
"file=C:\Mac-disks\9.2-usb-pci-ddk.img,format=raw,media=disk" -device
"sungem,netdev=network01" -netdev "tap,ifname=TapQemu,id=network01" -S
[New Thread 13304.0x1f00]
[New Thread 13304.0x2f84]
[New Thread 13304.0x3524]
[New Thread 13304.0x2b8c]
[New Thread 13304.0x368c]
[New Thread 13304.0x3668]
[New Thread 13304.0xf4c]
[New Thread 13304.0x49c]
[New Thread 13304.0x1d4c]
[New Thread 13304.0x7fc]
[Thread 13304.0x7fc exited with code 0]
[New Thread 13304.0x357c]
[New Thread 13304.0x7c0]
[New Thread 13304.0x3564]
[New Thread 13304.0x26f4]
[New Thread 13304.0x2f68]

Program received signal SIGSEGV, Segmentation fault.
0x00007ffb9edea991 in ?? () from c:\qemu-master-msys2\libglib-2.0-0.dll
(gdb) bt
#0  0x00007ffb9edea991 in ?? () from c:\qemu-master-msys2\libglib-2.0-0.dll
#1  0x000800000480bf50 in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
(gdb)

Even before I could attach to the process.

Best,
Howard