Re: FPU emulation incorrect for 68LC040?

Finn Thain
2010-07-22T01:14:35Z

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On Wed, 21 Jul 2010, Mattias Engdegård wrote:

> 21 jul 2010 kl. 22.32 skrev Geert Uytterhoeven:
>
> > As the 'LC040 doesn't implement FPU instructions, I'd expect it to
> > just generate an exception when the "fadd.d (a0)+,fp0" is encountered.
> > I.e. not do anything else, like postincrementing a0.
>
> According to the manual, it generates a special 8-word exception frame
> that contains the decoded effective address, as a help to the emulator.
> It only makes sense if the user can just use that EA right away (after
> having established that it is a memory operand). I suppose the only way
> to find out is to find someone with a genuine 'LC040 (a non-buggy one).

I have both kinds, buggy and non-buggy. Unfortunately, these machines
(PowerBooks) don't have working SCSI and the one with IDE has no Linux
filesystem.

But if you send me some inline asm, I'll patch it into busybox and test a
2.6.34 initramfs for you.

Finn