Re: ARM EABI port: minimum CPU choice
On Monday 12 June 2006 18:13, Martin Guy wrote:
> > > Mind u, even on v4t they will probably lose out worse in code size by
> > > having 2 extra instructions in every function than they would ever
> > > gain by interworking with thumb...
> > > so i guess LDM it is. That *does* exist and work on v4[t], true?
> >
> > False.
> >
> > The only way to do interworking on v4t is to use bx, which implies the
> > three instruction sequence. Yes, this really sucks, which is why it was
> > fixed in v5 :-)
>
> Sorry, I meant that the least bad option seems to be the LDM
> suggestion, and say "sorry guys, no thumb interworking on armv4t"
> rather than have ThumbInt work on ARMv4t at the expense of two extra
> instructions for everyone.
Ah, ok. In that case I agree.
> Am I right in thinking that using just bare LDM means that the distro
> will work on v4 and above, but Thumb interworking will only be usable
> with ARMv5t and above?
Correct. gcc still needs teaching how to do this, but that's a different
matter.
Paul
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