Subject: Re: [PATCH 0/6] MSI portability cleanups

From: David Miller <[email-masked]>
Date: Sun, 28 Jan 2007 15:37:07 -0800 (PST)

From: [email-masked] (Eric W. Biederman)
Date: Sun, 28 Jan 2007 16:26:44 -0700

> Yes.  In general the mainline linux kernel does not support certain
> classes of stupidity.  TCP offload engines, firmware drivers for
> hardware we care about, a fixed ABI to binary only modules, etc.
> It is the responsibility of the OS to setup MSI so we do it, not
> the firmware so we do it.

I absolutely disagree with you Eric, and I think you're being
rediculious.

If the hypervisor doesn't control the MSI PCI config space
register writes, this allows the device to spam PCI devices
which belong to other domains.

It's a freakin' reasonable design trade off decision, get over
it! :-)

Yes it can be done at the hardware level, and many hypervisor
based systems do that, but it's not the one-and-only true
way to implment inter-domain protection behind a single
PCI host controller.