Re: [Qemu-devel] qemu-system-sparc question?

[Paul Brook <paul@codesourcery.com>]

On Wednesday 11 October 2006 18:20, Blue Swirl wrote:
> >Sounds like you just want a bare-metal cross. There's absolutely no reason
> >to
> >run the editor, compiler or assembler on the target machine.
> >Many targets even have gdb simulators (MIPS, ARM and PPC do).
>
> I disagree, it's much easier to use a native compiler than to build a cross
> compiler, even with crosstool. 

Well, with native toolchains you get prebuilt binaries from your system 
vendor, so building them is a non-issue.

I don't believe that they're much easier to use in this context. If you're 
building prepackaged worktation software you might hit problems with crappy 
configure scripts. For a teaching environment I wouldn't expect it to be a 
problem, especially given the alternative is probably running on embedded dev 
boards.

> I don't think other compilers than GCC even support 
> cross setups.

That's definitely not true. Certainly anything targeting embedded systems are 
cross compilers (the target too small/slow to consider compiling natively), 
and I'd guess the same is true for many HPC systems (You don't want the 
clutter on your compute machines, esp. if they're used via batch jobs).
In my experience pretty much all development is done with cross compilers from 
workstations or commodity compile farms. This means windows/x86-linux, or 
maybe a few crufty old solaris boxes left over from when sparc was fast :-)

> BTW, we could easily design and implement an ideal CPU just for Qemu
> purposes. It could be unlike any existing hardware, for example with zero
> or thousands of registers. The problem would be making a compiler for the
> CPU, also porting some OS to it. Any GCC and Linux guru volunteers? CS
> research projects?

There's no such think as an Ideal cpu. It's like picking the right 
religion :-) If you want a toy cpu, there are things like mmix.
While arm, ppc, mips, sparc, etc each have their own peculiarities, they're 
all reasonably clean architectures. 

Paul