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

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

Hello,

(2014/06/07 2:40), David Young wrote:
> 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.

I am reading your draft proposal, so I comment about this later.

> 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.

I agree that the implementation can be MI. I try to implement it
can be MI easily.

How do you think of message-signalled interrupts (MSI) routing?
I want to route normal (and INTx) interrupts and MSI together,
so I think establishing "handler" should be able to be used
as a parameter of pic->addroute().

For this reason, I am implementing API for establishing MSI using
pci_intr_handle_t like pci_intr_establish(). The pci_intr_handle_t
for MSI consists of following three values:
    a) the "virtual IRQ number" (like IRQ number for normal interrupts)
       used in FreeBSD
    b) MPSAFE flag
    c) MSI flag (new)

This implementation is not so good because I tried to divert existing
code as much as possible. I think that I have better change parameters
of pic->addroute() or change pci_intr_handle_t to a struct.

> > + [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.

I am very glad for your help. INTRSTUB is close-coupling with IPL,
struct intrsource, and ioapic_{mask(),unmask()}. So I have difficulty
to do at first...


Thanks,

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