According to kernel.org:

Linux was first developed for 32-bit x86-based PCs (386 or higher). These
days it also runs on (at least) the Compaq Alpha AXP, Sun SPARC and
UltraSPARC, Motorola 68000, PowerPC, PowerPC64, ARM, Hitachi SuperH, IBM
S/390, MIPS, HP PA-RISC, Intel IA-64, DEC VAX, AMD x86-64 and CRIS
architectures. 

You could also probably check the arch/ subdirectory of the most current
kernel source for updates.

--
Michael Vieths
Foeclan at Visi.com

On Tue, 16 Apr 2002, Jon Schewe wrote:

> Someone at work asked me this question today and I couldn't find a master
> list.  What he'd like to find is a master list of all processors that Linux
> has been ported to so he can match this list up with a list of available
> processors for a project.  In particular he's looking at FPGAs.  
> 
> I tried the Hardware HOWTO, and it gave a list, but stated it wasn't
> complete.  Same thing out on kernel.org.  Has someone built such a list?
> 
> -- 
> Jon Schewe | http://mtu.net/~jpschewe
> For I am convinced that neither death nor life, neither angels 
> nor demons, neither the present nor the future, nor any 
> powers, neither height nor depth, nor anything else in all 
> creation, will be able to separate us from the love of God that 
> is in Christ Jesus our Lord. - Romans 8:38-39
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