Re: test13-pre5

[Andi Kleen]

On Sun, Dec 31, 2000 at 09:27:23AM -0800, Linus Torvalds wrote:
> 
> 
> On Sun, 31 Dec 2000, Andi Kleen wrote:
> > 
> > Sounds good. It could also be controlled by a CONFIG_SPACE_EFFICIENT for
> > embedded systems, where you could trade a bit of CPU for less memory overhead 
> > even on systems where u8 is slow and atomicity doesn't come into play
> > because it's UP anyways. 
> 
> UP has nothing to do with it.
> 
> The alpha systems I remember this problem on were all SMP.
[...]

I just checked all architecture manuals I could lay my hands on
(sparcv9, ppc32, mips r4400, parisc 1.1, alpha, sh is somewhere in
storage but as I remember it has it too) 
and they all seem to have at least store byte and mostly store
half words instructions. 

> 
> Imagine an architecture where you need to do a
> 
> 	load_32() 
> 	mask-and-insert-byte
> 	store_32()

iirc the Alpha guys found out that they couldn't drive half of the
available devices without byte store, and since then nobody has 
repeated that mistake @)

> 
> I don't think it's a good diea.

I don't see it. Just define x8 to u32 on old alpha and let most other architectures
be happy. 

-Andi