On Tue, May 08, 2018 at 09:35:10AM +0200, Geert Uytterhoeven wrote: > Hi Greg, > > On Tue, May 8, 2018 at 9:25 AM, Greg Kroah-Hartman > <[email protected]> wrote: > > On Tue, May 08, 2018 at 09:07:27AM +0200, Geert Uytterhoeven wrote: > >> On Tue, May 8, 2018 at 9:00 AM, Greg Kroah-Hartman > >> <[email protected]> wrote: > >> > On Mon, May 07, 2018 at 09:51:12AM +1200, Michael Schmitz wrote: > >> >> the BUG() was triggered by loading a Mac Nubus network card module on > >> >> a multiplatform kernel running on an Amiga machine. Up to Finn's Nubus > >> >> core rewrite (this February), we've seen no errors. Since then, Nubus > >> >> drivers fail to register because the Nubus bus is only registered on > >> >> Macs. > >> >> > >> >> Can't see link order involved here at all. > >> > > >> > The link order is totally involved here :) > >> > > >> > Link order determines the order in which init calls are run, so you need > >> > to ensure that your bus code comes before any drivers that use that bus > >> > code in link order. That way, at init time, your bus is created first, > >> > preventing this type of error to happen. > >> > >> The issue here is not due to link ordering, but due to the bus not being > >> registered on a system that doesn't have that particular bus. > > > > But how can that happen if the bus code is not present in the system at > > that point in time? Hardware doesn't matter at all here. > > The bus code is present in the system. > The bus is just not registered by the NuBus bus driver if the hardware > doesn't have a NuBus host.
Ah, that sounds like some "tight" coupling that other bus cores do not have. That's the confusion here that I have, sorry. > >> Akin to booting a kernel on an old PC without PCI, and loading a driver > >> module for a PCI network card. I guess that doesn't crash (because no one > >> has a PC without PCI anymore? ;-) > > > > No, it should work just fine, try it! :) > > > > The driver will not bind to anything, but the bus code should work > > properly, as long as it is initialized before the driver tries to > > register with that specific bus type. > > Hence the NuBus bus code should register the bus irregardless of the > presence of the NuBus host hardware. Yes it should. Shouldn't cause any problems as long as you don't have any hardware specific code in your bus code. Because of this, I don't think the original patch would help at all here, as the error would still be the same. So add a "is bus registered" flag to your bus and all should be fine. thanks, greg k-h
