On 04/09/2010 03:51 PM, Alan Cox wrote: >> Why is this different for 64-bit vs 32-bit? Can you point me to any >> references where I can learn about this? > > IMHO its wrong for both > > You can only reserve the region in question if you actually have a VGA > device and mappings present. > > It's wrong for non PCI systems > It's wrong for legacy ISA systems with monochrome video/no video > It's wrong for several embedded platforms. > It's wrong if PCI isn't your root bridge > > Basically the reservation is the wrong way to fix it. A much saner way to > fix it would be to simply keep a list of address ranges not to use for > PCI device relocation. For I/O ports of course we just fix up the PCI > resources of the device to list them as we discover it (IDE legacy). > > You don't want to put anything at the VGA address that needs assigning an > address. That is *totally* different to the question of whether you want > to believe the space is 'reserved'. If something is at that address then > presumably the firmware knows what it is doing. If a device driver wishes > to reserve that address it's doing so with more information, later in > boot so should be allowed to. That's what I mean with reserved, I'm using the term in the E820_RESERVED sense. As in "don't put anything there without it being an explicit assignment". -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
