• Bjorn Helgaas's avatar
    sparc/PCI: Stop reserving System ROM and Video ROM in PCI space · 3758a191
    Bjorn Helgaas authored
    Previously, pci_register_legacy_regions() reserved PCI address space under
    every PCI host bridge for the System ROM and the Video ROM, but these
    regions are not part of PCI address space.
    
    Previously, pci_register_legacy_regions() reserved the following areas of
    PCI address space under every PCI host bridge:
    
      [bus 0xa0000-0xbffff]    Video RAM area (VGA frame buffer)
      [bus 0xc0000-0xc7fff]    Video ROM
      [bus 0xf0000-0xfffff]    System ROM
    
    It does need to reserve the [bus 0xa0000-0xbffff] region (at least if
    there's a possibility of a VGA device below the bridge) because VGA devices
    can respond to that even if they don't describe it with a BAR.
    
    But the Video ROM and System ROM areas don't seem necessary because they
    are not areas that legacy PCI devices respond to.
    
    They appear to be copied from x86, where they describe areas of system
    memory that depend on BIOS conventions.  On x86, BIOS copies the option ROM
    of the primary VGA device to RAM at 0xc0000, and the 0xf0000-0xfffff region
    is reserved for the motherboard BIOS.  Neither of these things applies to
    sparc.
    
    Stop reserving the System ROM and Video ROM regions in PCI space.
    Signed-off-by: 's avatarBjorn Helgaas <bhelgaas@google.com>
    Acked-by: 's avatarDavid S. Miller <davem@davemloft.net>
    3758a191
pci_common.c 13.4 KB