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Date: Mon, 21 May 2001 08:47:38 -0700
To: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
From: Jonathan Lundell <jlundell@pobox.com>
Subject: Re: alpha iommu fixes
Cc: "David S. Miller" <davem@redhat.com>, Andrea Arcangeli <andrea@suse.de>,
        Andrew Morton <andrewm@uow.edu.au>,
        Richard Henderson <rth@twiddle.net>, linux-kernel@vger.kernel.org
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At 6:17 PM +0400 2001-05-21, Ivan Kokshaysky wrote:
>On Mon, May 21, 2001 at 06:55:29AM -0700, Jonathan Lundell wrote:
>>  8 slots (and  you're right, 6 is a practical upper limit, fewer for
>>  66 MHz) *per bus*. Buses can proliferate like crazy, so the slot
>>  limit becomes largely irrelevant.
>
>True, but the bandwidth limit is highly relevant. That's why modern
>systems have multiple root buses, not a bridged ones.

Sure, there are systems with multiple root buses (I'm a bit fuzzy on 
how well Linux handles that), and bandwidth is important, but it's 
simply wrong to assume that a particular root bus will never have 
more than 6 or 8 devices. There are legitimate cases (firewalls 
spring to mind) where port count is driven by other considerations 
than aggregate bandwidth.
-- 
/Jonathan Lundell.