Re: RFC: add MSI/MSI-X support to NetBSD

[Matt Thomas <matt%3am-software.com@localhost>]

On Jun 6, 2014, at 10:40 AM, David Young <dyoung%pobox.com@localhost> wrote:

> 1 An MI API for establishing "mailboxes" (or "doorbells" or whatever
>  we may call them).  A mailbox is a special physical address (PA) or
>  PA/data-pair in correspondence with a callback (function, argument).
> 
>  An MI API for mapping the mailbox into various address spaces,
>  but especially the message-signalling devices.  In this way, the
>  mailbox API is a use or an extension of bus_dma(9).
> 
>  Somewhere I have a draft proposal for this MI API, I will try to
>  dig it up.

Note that some system need to point the MSI at a specific address
(PPC PQIII for instance).