On Thu, Aug 21, 2014 at 4:34 PM, Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx> wrote: > A second step would then be to tune vgaarb's initial selection. > Bjorn, is it possible to verify which I/O ports are decoded by a PCI > device at the time of adding it to vgaarb? If so, how? I would like to > check for legacy VGA I/O range (0x03B0-0x03DF) and only let vgaarb set > a device as default if that I/O range is decoded by the device. I don't know of a way. I'm pretty sure VGA devices are allowed to respond to those legacy addresses even if there's no BAR for them, but I haven't found a spec reference for this. There is the VGA Enable bit in bridges, of course (PCI Bridge spec, sec 12.1.1. If the VGA device is behind a bridge that doesn't have the VGA Enable bit set, it probably isn't the default device. Bjorn -- 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
