On Fri, Mar 24, 2017 at 05:08:56PM +0000, Peter Maydell wrote: > On 24 March 2017 at 16:58, Markus Armbruster <arm...@redhat.com> wrote: > > "Sysbus" isn't a bus. In qdev's original design, every device had to > > plug into a bus, period. The ones that really didn't were made to plug > > into "sysbus". > > > > Pretty much the only thing "sysbus" devices had in common was that they > > couldn't be used with device_add and device_del. > > This isn't really true. Sysbus devices support having MMIO regions > and IRQ lines and GPIO lines. If you need those you're a > sysbus device; otherwise you can probably just be a plain old Device. > > > We fixed the design to permit bus-less devices, but we didn't get rid of > > "sysbus". > > Call it what you want, but we should have some common code support > for "I want to have MMIOs and IRQs and GPIO lines". You could > argue for moving all that into Device I suppose.
Even if we don't move all that into Device, this sounds like an argument for the existence of struct SysBusDevice. But I still don't understand the reason TYPE_SYSTEM_BUS still exists. -- Eduardo
