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Re: Modpost warning on Alchemy

To: Sergei Shtylyov <>
Subject: Re: Modpost warning on Alchemy
From: "Maciej W. Rozycki" <>
Date: Thu, 2 Aug 2007 14:27:29 +0100 (BST)
Cc: Ralf Baechle <>,
In-reply-to: <>
Original-recipient: rfc822;
References: <> <> <> <> <> <> <> <> <> <> <> <> <>

> > It does not help too much with a 32-bit virtual address space indeed.
> > Though I gather it has to be very sparsely populated as 16MiB is enough to
> > cover the whole configuration space of a single PCI bus tree.  Thus it has 
>    Hm, maybe 16 MiB would be enough indeed, as the Alchemy CPUs are known to
> not support bus masters behind PCI bridges...

 That is unrelated -- for configuration accesses (assuming the basic 
configuration space) you need: 8 bits for the bus number + 5 bits for the 
device number + 3 bits for the function number + 8 bits for the register 
number.  The total is 24 bits.  It is up to hardware to sort it out and 
put the right bits on the bus.


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