From mboxrd@z Thu Jan 1 00:00:00 1970 From: gerg@snapgear.com (Greg Ungerer) Date: Wed, 7 Mar 2012 21:54:12 +1000 Subject: [PATCH] ARM: remove ixp2000 platform In-Reply-To: <20120307091409.GL17370@n2100.arm.linux.org.uk> References: <1330450426-14639-1-git-send-email-robherring2@gmail.com> <201202281945.39419.arnd@arndb.de> <201203061412.00073.arnd@arndb.de> <20120307091409.GL17370@n2100.arm.linux.org.uk> Message-ID: <4F574C64.7010905@snapgear.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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