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

[David Young <dyoung%pobox.com@localhost>]

On Fri, May 30, 2014 at 05:55:25PM +0900, Kengo NAKAHARA wrote:
> Hello,
> 
> I'm going to add MSI/MSI-X support to NetBSD. I list tasks about this.
> Would you comment following task list?

I think that MSI/MSI-X logically separates into a few pieces, what do
you think about these pieces?

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.

2 For each platform, an MD implementation of the MI mailbox API.

3 Extensions to pci(9) for establishing message-signalled interrupts
  using either a (function, argument) pair, a PA, or a (PA, data) pair.
  I am pretty sure that the implementation of these extensions can be
  MI.

> + [amd64 MD]  refactor INTRSTUB
>   - currently, it walks the interrupt handler list in assembly code
>     - I want to use NetBSD's list library, so I want to convert this assembly
>       code to C code.

I support converting much of the interrupt dispatch code to C from
assembly.

Dave

-- 
David Young
dyoung%pobox.com@localhost    Urbana, IL    (217) 721-9981