Re: [virtio-comment] Re: [virtio] [PATCH] virtio: clarify feature negotiation

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

On Mon, Jan 24, 2022 at 04:42:35PM -0500, Michael S. Tsirkin wrote:
> So from that point of view, we are actually relaxing the requirements,
> and yes we'll need to carefully go over each instance of
> "offered".
> I thought I did, but now I did a quick grep again and I found instances
> in virtio-iommu.tex and virtio-gpio.tex
> Both of these are new, so I think we can just fix them to "negotiated".
> 
> Jean-Philippe, Viresh, what do you think? Would it be a problem to
> replace offered with negotiated, and restrict iommu and gpio drivers to
> access config space after FEATURES_OK?

No problem for iommu. The config space fields domain_range and input_range
are not useful to the driver before DRIVER_OK. Reading field bypass
earlier could be useful for debugging, but in that case going a few more
steps into device initialization wouldn't hurt.

Thanks,
Jean