On 2011-05-19 18:28, Gleb Natapov wrote: > On Thu, May 19, 2011 at 06:25:14PM +0200, Jan Kiszka wrote: >> On 2011-05-19 18:17, Gleb Natapov wrote: >>> On Thu, May 19, 2011 at 05:40:50PM +0300, Avi Kivity wrote: >>>> On 05/19/2011 05:37 PM, Anthony Liguori wrote: >>>>> >>>>> So.... do you do: >>>>> >>>>> isa_register_region(ISABus *bus, MemoryRegion *mr, int priority) >>>>> { >>>>> chipset_register_region(bus->chipset, mr, priority + 1); >>>>> } >>>>> >>>>> I don't really understand how you can fold everything into one >>>>> table and not allow devices to override their parents using >>>>> priorities. >>>> >>>> Think of how a window manager folds windows with priorities onto a >>>> flat framebuffer. >>>> >>>> You do a depth-first walk of the tree. For each child list, you >>>> iterate it from the lowest to highest priority, allowing later >>>> subregions override earlier subregions. >>>> >>> And how you set those priorities in a sensible way? Why two device on a >>> PCI bus will want to register their memory region with anything but >>> highest priority? And if you let PCI subsystem to assign priorities how >>> it will coordinate with ISA subsystem/memory controller what priorities >>> to assign to get meaningful system? >> >> Priorities >default will only be used for explicit overlays, e.g. RAM >> over MMIO in PAM regions. Non-default priorities won't be assigned to >> normal PCI bars or any other device's region. >> > That does not explain who and how assign those priorities in globally > meaningful way.
There are no global priorities. Priorities are only used inside each level of the memory region hierarchy to generate a resulting, flattened view for the next higher level. At that level, everything imported from below has the default prio again, ie. the lowest one. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux