On Fri, Mar 08, 2002 at 09:28:30PM -0500, duane duane wrote:
> Q: Code compatilibity
> 
> A: "720T and Strongarm are both v4. Use the
>    compiler from LART without optimasation.
>    for the architecture"
> 
>    From other sources I have learned that
>    at the core, everything is compatible.
>    By default, that's what most people do.
>    But if you use the StrongARM extension
>    it only works on the strong arm.

Not actually true.  The instruction set is defined by the architecture,
so as both StrongARM and ARM720 are the same architecture, they have
essentially the same ARM instruction set.  The ARM720T has an extra
feature (the 'T' means Thumb instruction set) which we don't use
currently.

If you build with the following options:

$ gcc -march=armv4 -mtune=strongarm ...

then the code will run on an ARM720, StrongARM, ARM920 etc.

However, if you're using special instructions for handling the cache and
MMU in the code (which would have to be coded using the gcc 'asm'
statement or in an assembly file), these make your code pretty processor
specific, but its independent of the arguments you supply to gcc.

>    It is, in effect like the 386/486/586
>    situation. :->

Its the architecture (ie, ARMv3/ARMv4/ARMv5) that is like that, not the
CPU type.

> Thank you for your answers they are quite helpful.

There's also the Integrator from ARM Ltd with the CM720T core module
header.  Its basically an AT-type eval board with PCI slots, the
ability to have multiple core modules and expansion modules plugged
onto it.  (core modules == processors).

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