From: Linus Torvalds <torvalds@osdl.org>
To: "Randy.Dunlap" <rddunlap@osdl.org>
Cc: Dave <dave.jiang@gmail.com>,
linux-kernel@vger.kernel.org, smaurer@teja.com,
linux@arm.linux.org.uk, dsaxena@plexity.net,
drew.moseley@intel.com
Subject: Re: clean way to support >32bit addr on 32bit CPU
Date: Mon, 10 Jan 2005 17:30:25 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.58.0501101722200.2373@ppc970.osdl.org> (raw)
In-Reply-To: <41E31D95.50205@osdl.org>
On Mon, 10 Jan 2005, Randy.Dunlap wrote:
>
> Speaking of fall-out, or more like trickle-down,
> I'm almost done with a patch to make PCMCIA resources use
> unsigned long instead of u_int or u_short for IO address:
Ahh, yes. That's required on pretty much all platforms except x86 and
x86-64.
Of course, since ARM and MIPS already do the "u_int" thing, and not a
whole lot of other architectures do PCMCIA, I guess it doesn't matter
_that_ much. Cardbus stuff should get it right regardless.
> typedef unsigned long ioaddr_t;
>
> and then include/pcmcia/cs.c needs some changes in use of
> ioaddr_t, along with drivers (printk formats).
>
> Does that sound OK?
> I guess that it would become unsigned long long (or u64)
> with this proposal?
I don't think ioaddr_t needs to match resources. None of the IO accessor
functions take "u64"s anyway - and aren't likely to do so in the future
either - so "unsigned long" should be good enough.
Having u64 for resource handling is mainly an issue for RAM and
memory-mapped IO (right now the 32-bit limit means that we throw away
information about stuff above the 4GB mark from the e820 interfaces on
x86, for example - that _happens_ to work because we never see anything
but RAM there anyway, but it means that /proc/iomem doesn't show all of
the system RAM, and it does mean that our resource management doesn't
actually handle 64-bit addresses correctly.
See drivers/pci/probe.c for the result:
"PCI: Unable to handle 64-bit address for device xxxx"
(and I do not actually think this has _ever_ happened in real life, which
makes me suspect that Windows doesn't handle them either - but it
inevitably will happen some day).
Linus
next prev parent reply other threads:[~2005-01-11 1:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-10 23:34 clean way to support >32bit addr on 32bit CPU Dave
2005-01-11 0:01 ` Slade Maurer
2005-01-11 0:00 ` Deepak Saxena
2005-01-11 0:35 ` Slade Maurer
2005-01-11 0:04 ` Roland Dreier
2005-01-11 0:09 ` Linus Torvalds
2005-01-11 0:28 ` Randy.Dunlap
2005-01-11 1:30 ` Linus Torvalds [this message]
2005-01-11 2:05 ` William Lee Irwin III
2005-01-11 3:38 ` Randy.Dunlap
2005-01-11 17:39 ` Randy.Dunlap
2005-01-11 18:18 ` Linus Torvalds
2005-01-11 19:40 ` Dave
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