From: gerg@snapgear•com (Greg Ungerer)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: remove ixp2000 platform
Date: Wed, 7 Mar 2012 21:54:12 +1000 [thread overview]
Message-ID: <4F574C64.7010905@snapgear.com> (raw)
In-Reply-To: <20120307091409.GL17370@n2100.arm.linux.org.uk>
On 03/07/2012 07:14 PM, Russell King - ARM Linux wrote:
> On Wed, Mar 07, 2012 at 09:40:31AM +0100, Linus Walleij wrote:
>> Network equipment seems to like using BE.
>>
>> I have some vague idea that this is beacuse IP packets are big
>> endian, and thus you can process them quickly by just casting fields
>> to e.g. u32 pointers and read them.
>>
>> I don't know if this is true, but seems to much of a correlation to
>> be pure coincidence. Thus a pretty interesting subject in
>> embedded ARM not used for tablets/mobile/generic computing
>> kind of stuff.
>
> ISTR Nicolas explained this to me as being an established thing in the
> comms sector. They expect BE and only understand BE.
>
> I did point out that you end up with many more endian conversions by
> going to BE, mainly because PCI is LE and all your PCI accesses have
> to be endian-swapped. So in terms of bandwidth, I'd expect an ARM
> PCI platform running in BE mode to have worse throughput than a LE
> PCI platform.
The built in ethernet interfaces on the ixp4xx family are not PCI
based. So they at least do not suffer from the BE/LE conversions
at the eth driver.
Regards
Greg
------------------------------------------------------------------------
Greg Ungerer -- Principal Engineer EMAIL: gerg at snapgear.com
SnapGear Group, McAfee PHONE: +61 7 3435 2888
8 Gardner Close, FAX: +61 7 3891 3630
Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com
next prev parent reply other threads:[~2012-03-07 11:54 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1330450426-14639-1-git-send-email-robherring2@gmail.com>
2012-02-28 19:45 ` [PATCH] ARM: remove ixp2000 platform Arnd Bergmann
2012-03-06 1:41 ` Nicolas Pitre
2012-03-06 2:44 ` Rob Herring
2012-03-06 9:16 ` Russell King - ARM Linux
2012-03-06 14:11 ` Arnd Bergmann
2012-03-06 16:51 ` Nicolas Pitre
2012-03-06 17:10 ` Arnd Bergmann
2012-03-06 17:38 ` Richard Cochran
2012-03-07 8:40 ` Linus Walleij
2012-03-07 9:14 ` Russell King - ARM Linux
2012-03-07 11:54 ` Greg Ungerer [this message]
2012-03-11 12:31 ` Krzysztof Halasa
2012-03-11 23:48 ` Greg Ungerer
2012-03-13 21:15 ` Krzysztof Halasa
2012-03-07 17:09 ` Imre Kaloz
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