Re: [hatari-devel] New WinUAE core issue with Bad Mood?

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On 8 Dec 2014 at 11:28, Nicolas Pomarède wrote:
> then I think there's an error in EmuTOS PMMU boot's sequence, because we
> have this code :
> $e00088 : 21fc 00e0 00b2 002c                  move.l    #$e000b2,$002c.w
> $e00090 : f039 0800 00e0 013e                  pmove     $e0013e,tt0
> $e00098 : f039 0c00 00e0 013e                  pmove     $e0013e,tt1
> $e000a0 : 21fc 00e0 00d0 002c                  move.l    #$e000d0,$002c.w
> $e000a8 : f039 4000 00e0 013e                  pmove     $e0013e,tc
> So, emutos first write to tt0/tt1, then it writes to tc ; the 2 moves to
> TTx are not made after a full 68030 was detected.
> It seems to be the opposite of what you describe ? Before reaching
> e00088, I don't see 68030 only instructions.
Sorry for my previous confusing comments - I assumed that the problem was
occurring in the detect_cpu code.  I'd forgotten that a minimal amount of CPU
detection was done earlier as part of reset handling.  The code you're looking
at is part of the code to disable the PMMU during a reset (necessary if the
reset is a software reset).

Here's the relevant part of the commented source FYI.  Please excuse the macros
for the instructions; they exist so that we can assemble the whole module as
68000 code:

    move.l  #not_68030,0x2c    // PMOVE is lineF on non-68030 systems
    PMOVE_TO_TTR0(zero)        // first initialise the TTRs (ACRs on a 68ec030)
    move.l  #mmu_done,0x2c     // since PMOVE_TO_TC doesn't exist on a 68ec030,
    PMOVE_TO_TC(zero)          //  we're done if we get a lineF exception ....
    bra.b   mmu_done
    move.l  #mmu_done,0x10     // if a MOVEC causes an exception, we're done
    moveq   #0,d0
    MOVEC_D0_ITT0              // first initialise the TTRs (ACRs on a 68ec040)
    MOVEC_D0_TC                // disable translate on 68040-60 (will error out
                               //  on a 68ec040)

As you can see, we assume it's a 68030/68ec030 and try to clear the TTRs/ACRs.
If that doesn't work, we try the 68040/68060 initialisation.  Otherwise it's a
68030/68ec030 and we try to clear the TC.  Whether or not that works, we're
done 68030/68ec030 PMMU initialisation.

Hope that clears things up,

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