On 15/10/2021 07:14, Laurent Vivier wrote:
> Le 13/10/2021 à 23:21, Mark Cave-Ayland a écrit :
>> According to both Linux and NetBSD, port B bit 6 is used on the Quadra 800 to
>> configure the GLUE logic in A/UX mode. Whilst the name VIA1B_vMystery isn't
>> particularly descriptive, the patch leaves this to ensure that the constants
>> in mac_via.c remain in sync with Linux's mac_via.h.
>>
>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>> ---
>> hw/misc/mac_via.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c
>> index 993bac017d..7a53a8b4c0 100644
>> --- a/hw/misc/mac_via.c
>> +++ b/hw/misc/mac_via.c
>> @@ -130,6 +130,10 @@
>> * On SE/30, vertical sync interrupt enable.
>> * 0=enabled. This vSync interrupt shows up
>> * as a slot $E interrupt.
>> + * On Quadra 800 this bit toggles A/UX mode which
>> + * configures the glue logic to deliver some IRQs
>> + * at different levels compared to a classic
>> + * Mac.
>> */
>> #define VIA1B_vADBS2 0x20 /* ADB state input bit 1 (unused on IIfx) */
>> #define VIA1B_vADBS1 0x10 /* ADB state input bit 0 (unused on IIfx) */
>>
>
> I'm not sure we need to keep in sync a word that neither used by linux or qemu (for now).
>
> Perhaps you can put a word from where it is (NetBSD)?
>
> It seems it's supported by all Quadra, not only Quadra 800 (see NetBSD comment in mac68k/machdep.c
>
> Anyway:
>
> Reviewed-by: Laurent Vivier <laurent@vivier.Eu>
Yeah, it's a hard one: you can see the bit referenced in the via_alt_mapping logic in
Linux but mac_via.h still shows it as VIA1B_vMystery (and indeed, it seems to have
different uses on different machines). The thought behind adding the comment was to
better explain the purpose of VIA1B_vMystery within the series.
ATB,
Mark.