mpc8241/8245 floating point unit
A message that is not in the archive (sent off-list or not yet received): [email protected]
I don't have 8241/8245 experience, but I do have 8260 experience (also uses the 603e core). Floating point (FPU) works well under linux.
Using floating point in the kernel is severely frowned on, however, because it takes time, both for the calculations and for additional FPU register store/restore operations (big speed hit). IIRC, you need to specially configure the kernel or modify the kernel because the kernel assumes it does NOT execute floating point instructions internally and therefore doesn't save/restore the FPU registers for its internal use (i.e. the kernel context does not have FPU registers saved/restored, user contexts do have FPU registers saved/restored). You don't want to go there unless you really, really have to and if you think about the problem a bit, I suspect you will discover you don't have to.
Pretty much any fairly recent gcc compiler should work.
For a very good head start in configuring your environment, see Wolfgang Denk's Embedded Linux Development Kit (ELDK).
http://www.denx.de/e/index1.php?main=doc/ELDK/index
gvb
Quoted 7 lines · At 09:38 AM 3/4/2003 -0500, [email protected] wrote:
Hi,
We are evaluating the mpc8241/8245 on the floating point unit. For they
are based on the 603e core, there is a hardware floating point support. And we are going to cross-compile the kernel and apps in intel platform. I am very interested to know
Quoted 10 lines
- whether the FPU is supported in the linux distribution in both user/kernel mode.
- If so, how should I compile for the applicaiton/driver with gcc?
- , and in which version of gcc does it support?Thanks very much for any comments.
Ivan Cheng
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Quoted 4 lines · Jerry Van Baren
I don't have 8241/8245 experience, but I do have 8260 experience (also uses
the 603e core). Floating point (FPU) works well under linux.
Does 8260 really have full FPU support ?. I think it only has FPU register set and it supports
FPU load and store instructions, but NOT arithmetic instructions. Am I right ?
HANYS
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Quoted 1 line · Jan Damborsky
Does 8260 really have full FPU support ?.
Yes.
-- Dan
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Quoted 8 lines
Quoted 4 lines
Does 8260 really have full FPU support ?.
Yes.
Thank for this information. It is new for me and important as well.
We are developing new board with 8260,
but we have thought there is only part of FPU working properly.
Thanks again, HANYS
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Quoted 5 lines · Jan Damborsky
Thank for this information. It is new for me and important as well.
We are developing new board with 8260, but we have thought there is only part of FPU working properly.
Make sure you are using the latest documentation. There shouldn't be anything left that indicates the FPU is not present, but early documention indicated there weren't FPU features.
Have fun.
-- Dan
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