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Re: Big endian in debian ARM

On Friday 27 May 2005 15:58, Lennart Sorensen wrote:
> On Fri, May 27, 2005 at 03:35:41PM +0200, Marco Canini wrote:
> > I've an IXP2400 based PCI card.
> > Inside the IXP2400 there's an Intel XScale processor.
> > I would like to run Debian ARM on it, but as far as I understand Debian
> > ARM is little endian. Is there a way to get a big endian version of
> > Debian ARM? My need for big endian is because the IXP2400 is a multi-core
> > processor which has 8 processors called Microengine running in big
> > endian.
> I thought the arm procesors (and the xscale) were only little endian
> capable.
> Even if the arm can do big endian, it certainly isn't something
> currently supported and probably won't be.
> I know the PPC can do both ways and the kernel developers have been very
> clear they have no intension of ever doing the other option on the PPC.
> Do the microengine processors run arm instructions?  I rather doubt it,
> in which case as long as you convert the data when exchanging between
> the xscale and the microengines you should be fine.  One of the two
> probably even has instructions to do so efficiently, unless the chip was
> badly designed (I doubt that somewhat).
> The arm wants little endian, so that's what you should run.  Whatever
> programs you load into the microengines is different since they aren't
> linux programs and they aren't arm programs (as far as I can tell) so
> their endianess doesn't matter.  Trying to change the endianess of a cpu
> and its OS just to avoid a few byte swaps does not make sense at all.
Normally you would be right but in the case of IXP2400 this's not necessarily 
true. Indeed the IXP2400 is a network processor and here is employed to 
transmit data at 3 Gbps. In my case I've no problems in making byte swaps, 
but I had preferred not to. However in general making byte swaps for every 
packet you process would result in a performance loss.

Considering that it's an embedded system with nfs root fs, serial console and 
network access, what is the suggested/simplest method to install Debian ARM?


> Len Sorensen

Marco Canini

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