Re: [Qemu-discuss] How to select specific qemu net 'nic' device

[Edgar E. Iglesias]

On Fri, Nov 23, 2018 at 02:59:32PM +0500, mbilal wrote:
> Hi,
> 
> Thanks for reply.
> 
> According to your suggestion I've tested with 3.1 rc2 release and problem is
> still exist in this release also.
> 
> Here is my reproducible scenario.


Thanks,

I've had a look and the assert looks bogus to me.
We shouldn't be asserting on RX descriptor setups when the receiver is disabled.

I'll send a patch in a moment.

Best regards,
Edgar



> 
> QEMU launching
> --------------
> 
> ./qemu-system-aarch64 -M xlnx-zcu102 -m 1G -kernel /dev/null -S -s  -net nic
> -net nic -net nic -net nic -net user,hostfwd=tcp::8080-:8080 -smp 1 -serial
> stdio -serial /dev/null
> 
> gdb session
> ------------
> 
> (gdb) file zcu102_net_uni.out
> Reading symbols from zcu102_net_uni.out...done.
> (gdb) tar rem :1234
> Remote debugging using :1234
> _ld_text_start () at os/arch/armv8/common/arch_asm.S:381
> 381       MOV     X14, X0
> (gdb) load
> Loading section .text, size 0x59c0c lma 0x0
> Loading section .rodata, size 0x2bbc lma 0x59c0c
> Loading section .rtl.data, size 0x770 lma 0x5c7c8
> Loading section .data, size 0x4dc lma 0x5cf54
> Start address 0x0, load size 381972
> Transfer rate: 23313 KB/sec, 2021 bytes/write.
> (gdb) c
> Continuing.
> ^C
> 
> 
> So any breakpoint or Ctrl-C asserts the QEMU.
> 
> qemu-system-aarch64: qemu-3.1.0-rc2/hw/net/cadence_gem.c:982: gem_receive:
> Assertion `!first_desc' failed.
> 
> 
> Our networking demo application running fine unless you interrupt the GDB
> (either with breakpoints or interrupt signal).
> You can see following message on QEMU console which is the indication of
> demo is fine (it also well tested on actual hardware)
> 
> Open the following Nucleus node address in your web browser:
>     http://127.0.0.1:8080/
> 
> 
> I'm attaching demo application binary.
> 
> 
> 
> 
> Thanks for care about this issue,
> -Bilal
> 
> 
> 
> On 11/23/2018 01:59 PM, Peter Maydell wrote:
> > On 23 November 2018 at 04:13, mbilal <address@hidden> wrote:
> > > Hi,
> > > 
> > > I'm using qemu emulation for xilinx zcu102 platform, this board have four
> > > networking GEM0, GEM1, GEM2 and GEM3 devices.
> > > 
> > > To run network demo on this board *only* require GEM3 device to be 
> > > configure
> > > while other GEM devices don't need to be configure, that's why u-boot and
> > > other RTOS only configure GEM3 device.
> > > 
> > > 
> > > QEMU is enabling these GEM devices  with networking '-net nic' option and
> > > QEMU consider first '-net nic' option for GEM0 and second '-net nic' 
> > > option
> > > for GEM1 and so on. that's why if need to enable GEM3 network device we 
> > > must
> > > need to give following full command line options
> > > 
> > > -net nic -net nic -net nic -net nic -net user, ...
> > > 
> > > In this way all four GEM devices would be enable but first three GEM0-GEM2
> > > devices are un-configured and useless. In our case QEMU is being *crashed*
> > > due to trying to use these un-configured GEM devices to o send/receive GDB
> > > breakoint/interrupt cause. IIUC QEMU uses first device in the -nic loop
> > > i.e
> > > 
> > > qemu-system-aarch64: hw/net/cadence_gem.c:921: gem_receive: Assertion
> > > `!first_desc' failed.
> > 
> > If QEMU asserts like this, this is a bug in QEMU. I've cc'd
> > the maintainers of the Xilinx board.
> > 
> > Could you provide a complete set of instructions to reproduce
> > this bug, please ? (full command line, guest image, etc)
> > 
> > Could you also tell us which version of QEMU you are using?
> > If possible, try with the current git master or
> > with the 3.1 rc2 release candidate we've just put out, to
> > see if it's already been fixed.
> > 
> > thanks
> > -- PMM
> >