MPC8xx: Bad emulation
wd at denx.muc.de
Fri Jun 11 19:11:17 EST 1999
In message <3760B964.E1424E37 at switchboard.ericsson.se>
Marcus Sundberg wrote:
> Don't use floating point instructions in the programs, embedded PPC
> doesn't have FPUs. Use -mcpu=860 -msoft-float when compiling to use
Yes, I know this.
> soft floats (note that all FP using programs and libraries must
> be recompiled with these options to work properly).
> You will also need to patch glibc to remove the FP inline assembly
> and the inline memcpy which assumes 32 byte cache lines.
And this is exactly the point that makes this option unacceptable
from the practical point of view. We would have to build special
MPC8xx releases of LinuxPPC then.
How does this work for you? You may have a small embedded system with
just a small set of applications in mind, where `-mcpu=860
-msoft-float' works fine; but once you have Linux running on such a
board, it *always* happens that you run into situations where you
want to do some things in native mode - well, no problem: mount the
Linux environment over NFS. Then you can dynamically load and unload
(and debug) device drivers, etc.
And suddenly you will need this tool and that one, too.
Your customer asks: And could I run a web server on this box, too?
You say: well, no problem, just start appache - and "Bad emulation".
There are *many* situations where it is really necessary to be able
to run _any_ binary from a standrad LinuxPPC distribution on the 860,
too. I agree that it makes sense to recompile dedicated applications
for an embedded solution.
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd at denx.de
"He only drinks when he gets depressed." "Why does he get depressed?"
"Sometimes it's because he hasn't had a drink."
- Terry Pratchett, _Men at Arms_
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