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To: "Maciej W. Rozycki" <>
Subject: Re: [PATCH]PCI on SWARM
From: Jes Sorensen <>
Date: 20 Oct 2004 01:57:36 -0400
Cc: Ralf Baechle <>, Manish Lachwani <>,
In-reply-to: <>
Original-recipient: rfc822;
References: <> <> <> <> <> <> <> <> <>
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3
>>>>> "Maciej" == Maciej W Rozycki <> writes:

Maciej> On Mon, 18 Oct 2004, Jes Sorensen wrote: 
>>  Dual address cycles, ie. 64 bit addressing is fscked on the 1250
>> from what I remember. Correct way to work around this is to stick
>> all physical memory outside the 32 bit space into ZONE_HIGHMEM -
>> had a patch for 2.4, but I lost it ages ago ;-(

Maciej>  The BCM1250A's PCI is obviously 32-bit only (the host bridge
Maciej> is explicitly documented not to support DACs), but you need to
Maciej> use 64-bit addressing to access the whole 4GB range -- the bus
Maciej> is decoded starting from 0xf800000000 and 0xf900000000, with a
Maciej> different byte lane swapping policy for each of these areas.
Maciej> For limited access for 32-bit software, you can use alternate
Maciej> mappings at 0x40000000 and 0x60000000, but they provide only
Maciej> 512MB of space each.

Yeah it seems to be documented, it's highly unfortunate that anybody
will release a chip which doesn't support DAC but will support memory
outside the 4GB range. I'd be highly embarrassed if I had done the
chip, but thats just me.

I think you are right about the HT part.


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