Re: [RFC PATCH 0/7] Revamped region creation

[Ben Widawsky <ben.widawsky@intel.com>]

On 22-03-16 16:02:56, Ben Widawsky wrote:
> From: Ben Widawsky <ben@bwidawsk.net>
> 
> I will be on vacation all of next week so I'm trying to get this out now, even
> though I still need to go over the locking and lifetimes. I'm certain there are
> still issues there. I did want to start the discussion sooner rather than later
> around the ABI changes.
> 
> The major changes from this series are:
> - disambiguation of decoder types
> - endpoint decoders size and volatility must be set
> - regions are comprised of decoders instead of devices
> - device physical address space is now managed

Dan/all, I used gen_pool API to manage the device's address space. When I
originally authored the patches, I was under the impression that HDM decoders
could be sparsely enabled [1], which leads to the device physical address space
being sparsely populated. As it turns out, this is explicitly disallowed
(8.2.5.12.20). However, I need /some/ way to manage address space, and on third
thought, maybe it's worth it to just leave the gen_pool usage as is.

What are your thoughts? I think the resource APIs are a little klunky given that
we may not yet have sysram mapping for the HDM decoders in the current
programming model. Ranges are possibly usable. gen_pool provides a lot of
flexibility, but it is more complex (but the code is written).

[1]: Practically speaking, decoders can be sparsely enabled. If you set base ==
limit for a decoder it will decode 0 address space. This trick might be nice to
use later.