From: Roland Dreier <rdreier@cisco.com>
To: "Shawn Jin" <shawnxjin@gmail.com>
Cc: "Jeff Garzik" <jeff@garzik.org>, linux-kernel@vger.kernel.org
Subject: Re: Multiple MSI messages support
Date: Tue, 30 Oct 2007 22:17:42 -0700 [thread overview]
Message-ID: <ada1wbbj215.fsf@cisco.com> (raw)
In-Reply-To: <c3d0340b0710302205i7129f78bq9a4af7744ee60b6d@mail.gmail.com> (Shawn Jin's message of "Tue, 30 Oct 2007 21:05:36 -0800")
> My interpretation of this statement is that you have to use MSIX if
> multiple MSI messages are required on Linux.
Yes, Linux only supports multiple messages with MSI-X, not MSI. This
is an architectural limitation of "Intel-style" interrupt controllers
(x86 and ia64). It is also a limitation of the Linux's MSI API, since
there are platforms and devices for which an OS could allocate
multiple MSI messages, but Linux has no interface that allows that.
The historical reason for the Linux interface is simply that Intel
platforms were the first place that MSI/MSI-X was supported.
- R.
prev parent reply other threads:[~2007-10-31 5:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-30 21:13 Multiple MSI messages support Shawn Jin
2007-10-30 22:23 ` Jeff Garzik
2007-10-30 22:51 ` Roland Dreier
2007-10-30 23:02 ` David Miller
2007-10-31 1:34 ` Shawn Jin
2007-10-31 4:00 ` Jeff Garzik
2007-10-31 5:05 ` Shawn Jin
2007-10-31 5:17 ` Roland Dreier [this message]
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