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Message-ID: <16215.12889.496875.461596@nanango.paulus.ozlabs.org>
Date: Thu, 4 Sep 2003 22:38:49 +1000 (EST)
From: Paul Mackerras <paulus@samba.org>
To: Christoph Hellwig <hch@lst.de>
Cc: "David S. Miller" <davem@redhat.com>, torvalds@transmeta.com,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fix ppc ioremap prototype
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Christoph Hellwig writes:

> Yupp.  This makes me question again how the phys_addr_t thing is
> supposed to work at all given struct resource uses unsigned long
> for start and len, so the whole generic resource infrastructure
> doesn't know about the higher bits...

That's what fixup_bigphys_addr is for.  Basically, on the 440 the
first 4GB of physical address space is all RAM.  PCI memory space
occupies 2GB from 380000000 - 3ffffffff.  So if ioremap is given an
address between 2GB and 4GB, it is assumed to be from a PCI driver,
and fixup_bigphys_addr adds on the 0x300000000.

> Could someone point me a to a driver actually making use of the
> extented ioremap address on ppc 44x?

drivers/net/ibm_emac/ibm_ocp_enet.c in 2.4 does - it's an ocp driver,
not a pci driver.  Yes, we owe Jeff Garzik a 2.5 version of that
driver.

Paul.
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