Subject: Re: Differences between MPC823 powerpc & any other powerpc

From: Mark Hatle <[email-masked]>
Date: Mon, 11 Sep 2000 10:51:23 -0700

[email-masked] wrote:
>
> At 11:48 AM 5/12/00 +0100, you wrote:
> >
> >Hello,
> >
> >I would like to know what are the basic difference between the MPC823
> >PowerPC and any other PowerPC , say, the G4? Why dont the binaries running
> >on G4 not work correctly on the MPC823?
>
>         For starters the MPC823 has no FPU. I think you could compile FPU
> emulation into the kernel to remedy this but I'm not sure. G4 compiled
> programs may use alti-vec instructions but I'm not sure on this either.
>

In addition to no FPU, the 8xx series also has half of the cachelines
that all
of the other PPC's have.  (4xx, 6xx, 7xx, 74xx, 82xx)  This causes a
problem
with glibc [and possibly other things] which expect a certain line size
to do
fast memset's, memcpy's etc.  (The result of having the wrong cacheline
size
is to miss area's of memory in the previous listed functions.)

Also w/ the no FPU comes ABI issues including (especially?) var args
issues.

--Mark

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