Re: [PATCH v2 3/3] shared memory: Define mmio registers

[Cornelia Huck <cohuck@redhat.com>]

On Fri, 22 Feb 2019 11:54:33 +0000
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Define an MMIO interface to enumerate and map shared
> memory regions.
> 
> Note: This hasn't been implemented.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  content.tex | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)

(...)

> @@ -1815,6 +1840,13 @@ If both values are valid, it MUST read \field{DeviceID}
>  and if its value is zero (0x0) MUST abort initialization and
>  MUST NOT access any other register.
>  
> +Devices expecting shared memory regions MUST enumerate the
> +regions by selecting each region in tern and checking that the

s/tern/turn/

> +length is not -1.
> +
> +Devices not expecting shared memory MUST NOT use the shared
> +memory registers.

Isn't that the _driver_ requirements section? These sentences also make
more sense if they talk about a driver expecting something.

What I also find a bit confusing is the requirement that they enumerate
all regions (at least, that's how I read it.)

Say we have a device type with shared regions foo, bar, and the
optional baz. It should be fine if a driver finds foo, bar, and baz; as
well as if a driver only finds foo and bar. Conversely, a driver only
looking for foo and bar should work with a device exposing foo, bar,
and baz.

> +
>  Further initialization MUST follow the procedure described in
>  \ref{sec:General Initialization And Device Operation / Device Initialization}~\nameref{sec:General Initialization And Device Operation / Device Initialization}.
>