Re: [PATCH v6] can: virtio: Add virtio CAN driver

[Francesco Valla <francesco@valla.it>]

Hello Harald, Oliver,

On Tue, Jan 06, 2026 at 08:43:42PM +0100, Oliver Hartkopp wrote:
> 
> 
> On 06.01.26 17:50, Harald Mommer wrote:
> > > With the plain 'cangen' you are not really flooding the interface, since
> > > you are only sending a random CAN frame every 200ms. The only way I can
> > > reproduce this behaviour in a consistent manner is running from the host:
> > > 
> > >      while true; do cansend vcan0 134#00; done
> > > 
> > > which seems to generate the maximum amount of traffic.
> > > 
> > > This is not of course a realistic bus load, but is leading the system
> > > (at least on my setup) to a corner case somewhere.
> > 
> > I have no idea how long the shell needs for a loop, always used cangen -g 0 to stress the setup which is most probably faster than the shell interpreter, and sometimes did this for both directions (RX and TX).
> > 
> > Full load is a realistic setup. And even if it was not, if something stopped working or worse crashes torturing the setup this was a problem.
> > 
> 
> Yes. cangen -g 0 -i <interface> creates full load - even on real CAN
> interfaces. You can also generate fixed content if you want to omit the
> generation of randomized content. 'cangen -?' prints a help text.
> 

I agree with both of you - I was simply arguing that a plain 'cangen'
with no parameters is not really loading the interface.

For some reason, I was only able to trigger the unwanted behavior with
cansend in a while loop and not with cangen -g 0, even with fixed ID and
payload. However, I suspect the issue is a matter of timing and
coincidences rather than load level.

> Best regards,
> Oliver
> 

Regards,
Francesco