From: Matthew Wilcox <willy@debian.org>
To: Matt Porter <mporter@kernel.crashing.org>
Cc: Matthew Wilcox <willy@debian.org>,
Jeff Garzik <jgarzik@pobox.com>,
linux-kernel@vger.kernel.org,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
davem@redhat.com
Subject: Re: Message Signalled Interrupt support?
Date: Mon, 12 May 2003 19:20:23 +0100 [thread overview]
Message-ID: <20030512182023.GA29534@parcelfarce.linux.theplanet.co.uk> (raw)
In-Reply-To: <20030512104300.A23510@home.com>
On Mon, May 12, 2003 at 10:43:00AM -0700, Matt Porter wrote:
> I've also done some thought for PPC440xx's PCI MSI support. It isn't
> strictly necessary to have a new request_msi() if the kernel "does
> the right thing". request_irq() already hooks using an interrupt
> value that is virtual on many platforms.
Yes, but ideally this kludge would go away...
> In that case, the PCI
> subsystem would only need to provide an interface to provide
> the architecture/platform specific inbound MSI location. The PCI
> subsystem would then find all MSI capable PCI devices, and assign
> the appropriate number of unique messages and inbound MSI address
> to each device via the speced PCI MSI interface. The PCI subsystem
> would also be responsible for maintaining a correspondence between
> virtual Linux interrupt values and MSI values.
>
> Software specific to the PCI MSI capable "Northbridge", will then
> route general MSI interrupt events to some PCI subsystem helper
> functions to verify which MSI has occurred and thus which Linux
> virtual interrupt.
That sounds like a lot of overhead. In particular it means we keep
converting to and from `virtual IRQs'. I would hope the MSI work would
allow us to tie in at a lower level than virtual interrupts. I was
thinking an interface would look something like:
void *request_msi(struct device *dev,
irqreturn_t (*handler)(int, void *, struct pt_regs *),
unsigned long irqflags,
void *dev_id)
You need a struct device to figure out which interrupt controller it
needs.
--
"It's not Hollywood. War is real, war is primarily not about defeat or
victory, it is about death. I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk
next prev parent reply other threads:[~2003-05-12 18:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-12 16:32 Message Signalled Interrupt support? Jeff Garzik
2003-05-12 16:53 ` Matthew Wilcox
2003-05-12 17:20 ` David S. Miller
2003-05-12 18:54 ` Mika Penttilä
2003-05-12 17:43 ` Matt Porter
2003-05-12 18:20 ` Matthew Wilcox [this message]
2003-05-12 18:48 ` Matt Porter
2003-05-13 11:21 ` Ivan Kokshaysky
2003-05-12 17:26 Chuck Ebbert
2003-05-12 17:53 Nakajima, Jun
2003-05-12 18:26 Nakajima, Jun
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20030512182023.GA29534@parcelfarce.linux.theplanet.co.uk \
--to=willy@debian.org \
--cc=davem@redhat.com \
--cc=ink@jurassic.park.msu.ru \
--cc=jgarzik@pobox.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mporter@kernel.crashing.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).