|Re: [hatari-devel] Possible bug in 060 exception stack frames|
[ Thread Index |
| More lists.tuxfamily.org/hatari-devel Archives
> Yes, I tested it with real 68040, those 3 instructions won't modify
Thats strange and does not make much sense to me, especially because it
apparently only affects 040. I'll see whether i can update the test
program so it does not report failures for this when run on 040.
68881/68882 also does not update FPIAR in this situation.
FPIAR behavior has changed between 6888x and 68040/060.
68881/2: FPIAR is only modified if instruction can generate arithmetic
exception and at least one arithmetic exception is enabled in FPCR. This
is also mentioned in 68881/2 documentation.
But 68040 and 68060 will always modify FPIAR if instruction can generate
any arithmetic exception, even if arithmetic exceptions are disabled.
FPIAR is also modified if instruction generates non-arithmetic exception
that 6888x does not generate, for example if instruction or addressing
mode is unimplemented (that is implemented in 6888x).
I can't be 100% sure but so far this seems to match real hardware behavior.