Date: Sun, 14 Dec 2008 01:12:10 -0700
From: Grant Grundler <grundler@parisc-linux.org>
To: Manu Abraham <abraham.manu@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: MSI messages
Message-ID: <20081214081210.GC13371@colo.lackof.org>
References: <49438290.1080502@gmail.com>
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On Sat, Dec 13, 2008 at 01:38:24PM +0400, Manu Abraham wrote:
> Hi,
> 
> I am wondering how to handle this:
> 
> Does the kernel somehow handle MSI message readback from the PCI config space 
> for the MSI message as described in 6.8.1 of the PCI Bus specification 2.3 or 
> does a device specific driver have to read the Message Address and Data ?
> 
> To put it short: i am wondering how i should read the MSI messages.

The "message" is actually mapped to an the interrupt vector by the core
generic interrupt handling code in the kernel.

A "GSI" (Generic Sys Interrupt?) is associated with each entry in
the MSI-X table. Driver then calls request_irq() to bind an interrupt
handler to each GSI. So the driver never directly sees the "message".

hth,
grant
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