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I'm trying to add DMA to NuBus and friends. I have the DMA itself working, but there's a hitch. Some of the cards use a dp83932 device, which needs a device name and a space number to feed to an address space finder, ideally at mconfig time.

The way the card can know that is that the root bus calls set_nubus_tag() on each card_interface at device_resolve_objects time. I thought I could fix that by having the card implement its own device_config_complete and set the tag when it's valid, but if I throw device_missing_dependencies there the core gets angry and if I don't throw anything it proceeds to try and resolve the object finders without my being able to set the tag.

How do I make this work short of hardcoding device tags in the card?

Maybe this? (not 100% sure)

As I said in the OP, I tried that. The problem is the init callbacks aren't fine-grained enough to make that work. I need a "call this after the parent object is completely initialized but child objects haven't been".

The only callback you get before object finders are resolved is config complete. You need to be kind of careful with config complete because there’s some weirdness with what happens with how slot cards are instantiated and added. The resolve objects callback happens after object finders are resolved.

You obviously can’t throw device_missing_dependencies from anywhere except device_start because MAME assumes all the other callbacks can be called in tree walk order without having to worry about backtracking to deal with stragglers.

Anyway, I don’t know if there’s a nice way to do this with an object finder. In most cases, when there are situations where cards need to know about some resource (a bus, address space or something), they’re supplied with a pointer to the object itself at resolve objects or start time, not information for setting up an object finder.

The only thing I can think of at the moment that might work is:

• In device_config_complete for the bus, tell the slots what the space finder’s details are.
• In device_config_complete for the cards, ask the slot what the space finder’s details are and pass that on to the DP83932 .

The slots will definitely be present when device_config_complete is called for the bus. When device_config_complete is called for a card, its host slot will definitely be present (it’s the parent device).

Just remember the card needs to survive device_config_complete without a slot for -valid, -listxml, etc. It doesn’t have to do anything useful, but it needs to not crash if its parent isn’t a slot.

Thanks, I'll give that a try.