Re: [ANNOUNCE] ktimers subsystem

Roman Zippel
2005-09-27T16:48:43Z

Hi,

On Sun, 25 Sep 2005, Thomas Gleixner wrote:

> On Sun, 2005-09-25 at 01:45 +0200, Roman Zippel wrote:
>
> > The multiply is not necessarly cheap, if the arch has no 32x32->64
> > instruction, gcc will generate a call to __muldi3().
>
> Can you please point out which architectures do not have a 32x32->64
> instruction ?

I have no complete overview. I know that Motorola actually removed that
instruction in the M68060 (it causes an emulation trap) and it's still not
back in newer ColdFire cpus. For arm it's an optional instruction in
earlier versions (v3). For ppc it's splitted into two instructions.

For the rest you might want to check <asm/div64.h>, if div64 has to be
emulated, there are good chances this instruction has to be emulated as
well (especially in smaller embedded archs).

bye, Roman