On 2011-06-08 13:33, Peter Maydell wrote: > At the moment you can't really implement one sysbus device by saying > that it's composed of a set of other sysbus devices. This patch adds > new functions sysbus_pass_mmio() and sysbus_pass_one_irq() which > allow a sysbus device to delegate an MMIO or IRQ to another sysbus > device (The approach is inspired by the existing sysbus_pass_irq() > which lets a sysbus device delegate all its IRQs at once). > > This works; the most obvious deficiency is that the subcomponent > device will still appear as its own device on the bus. > > So: is this a reasonable solution to the problem, or an unacceptable > hack? Comments welcome :-)
Sounds more like a little hack. :) The relationships should be expressed via qdev, not yet another sysbus-specific extension. Generally, many services of sysbus should rather be generic qdev things. Is there anything that today prevents creating a local bus and attaching the component devices to that? If it's multi-bus support, that should to be added anyway. Passing-through of MMIO and IRQs is still a worthwhile generic service, then probably qbus associated. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux
