Re: [virtio-dev] Re: [virtio-comment] Re: [PATCH v18] virtio-net: support inner header hash

[Heng Qi <hengqi@linux.alibaba.com>]

å 2023/6/22 äå3:35, Michael S. Tsirkin åé:
> On Wed, Jun 21, 2023 at 07:28:33PM +0000, Parav Pandit wrote:
> > > From: Michael S. Tsirkin <mst@redhat.com>
> > > Sent: Wednesday, June 21, 2023 3:26 PM
> > >
> > > On Wed, Jun 21, 2023 at 05:52:28PM +0000, Parav Pandit wrote:
> > > > > From: Heng Qi <hengqi@linux.alibaba.com>
> > > > > Sent: Wednesday, June 21, 2023 12:46 PM
> > > >
> > > > > SET carries an additional 32 bits of information. But if you think
> > > > > this will make the overall structure more concise, I'm ok.
> > > > If it is placed in single structure than it needs to be reworded to remove WO
> > > or RO notion.
> > >
> > > Not really. all of structure is RO and WO.
> > For the device, what is the meaning of driver writing supported_tunnel_types in SET command?
> > Ignore? It doesn't make sense to pass something to ignore.
> It can be helpful for debugging. E.g. if driver sets
> a bit that device does not recognize, it can figure
> out that driver has it set in supported mask.
> Or if it seems like a waste we can just ask drivers to
> put 0 there, works for me too.

For the SET command, it is a bit strange to have the driver write 
support_hash_tunnel_types to the device.
'supported' is the capability of the device, 'enabled' is the capability 
of the driver.
The driver should be read-only to 'supported', the driver should not try 
to write it.

Thanks.

> > Two structures are cleaner.
> Frankly what's cleaner is what RSS is doing, supported mask in config
> space. Was this discussed in some version? I don't remember.
>
> > > > This also requires additional sw to indicate dma attributes to be RW when
> > > mapping this area.
> > > > And extra text to indicate that supported_hash_tunnel_types to be ignored
> > > on set command.
> > > > Two structures are more cleaner serving its purpose.
> > > No because all of structure is RO or WO.
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