Re: vmxnet3 no longer functional on DPDK 21.11

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Jan 09, 2024 at 09:21:47AM -0600, Lewis Donzis wrote:
> 
> 
> ----- On Jan 9, 2024, at 8:28 AM, Bruce Richardson bruce.richardson@intel.com wrote:
> 
> > On Tue, Jan 09, 2024 at 07:46:47AM -0600, Lewis Donzis wrote:
> >> Hi, Bruce.
> >> 
> >> I'm even less familiar with it, but we do quite a lot of testing using VMs, so
> >> it's been quite handy.
> >> 
> >> Your patch seems very reasonable, however it also produces a warning:
> >> 
> >> ../drivers/net/vmxnet3/vmxnet3_ethdev.c:264:1: warning: unused function
> >> 'vmxnet3_enable_all_intrs' [-Wunused-function]
> >> 
> >> Adding an #ifndef around vmxnet3_enable_all_intrs() eliminates that warning.
> > 
> > Right, I should have compile-tested on FreeBSD myself, before sending the
> > suggestion. Patch has now been submitted. Please test and ack if the fix
> > works for your use-cases, thanks.
> 
> I compiled it and ran it just now and it appears to work just fine.  Thanks very much for submitting.
> 
> > In general, yes we try and avoid interrupts on the data-path or fast-path
> > and use polling. However, for some use-cases where traffic levels are low,
> > interrupts may make sense to save power for fast-path. Even if not,
> > interrupts are useful for things like error conditions or for monitoring
> > link-status changes (LSC). Unfortunately, we don't have any interrupt
> > support on BSD, so fixes like this are necessary.
> 
> That makes sense.  Makes me wonder why there's no interrupt support on BSD, i.e., maybe it's better to fix that than to have to fix "avoiding it" in the drivers?

Sadly, interrupt support was never implemented for BSD, which is why it is
missing. If someone has the time and interest to do up the patches to add
it, it would be a welcome addition to DPDK.

> 
> I kind of feel like we're a bit orphaned in the FreeBSD world.  I don't know how many others are using BSD, but it seems like we're in a relatively less-supported environment.
> 

Linux is the dominant environment for DPDK, which does mean it gets most of
the attention. However, we do want to keep supporting BSD, so please
continue to flag issues to the community as you encounter them. Smaller
bugs we can certainly endeavour to fix, but adding things like interrupt
support probably requires someone to explicitly step up and dedicate time
to implementing it properly.

Regards,
/Bruce