On 04/07/2010 04:05 PM, Bjorn Helgaas wrote: > On Wednesday 07 April 2010 04:45:30 pm Yinghai wrote: >> On 04/07/2010 02:06 PM, Bjorn Helgaas wrote: >>> >>> Currently, we only reserve the legacy VGA area [mem 0xa0000-0xbffff] on >>> x86_32. But this legacy area is also used on x86_64, so this patch >>> reserves it there, too. >>> >>> If we don't reserve it, we may mistakenly move a PCI device to that area, >>> as we did here: >>> >>> pci_root PNP0A03:00: host bridge window [mem 0xff980800-0xff980bff] >>> pci_root PNP0A03:00: host bridge window [mem 0xff97c000-0xff97ffff] >>> pci 0000:00:1f.2: no compatible bridge window for [mem 0xff970000-0xff9707ff] >>> pci 0000:00:1f.2: BAR 5: assigned [mem 0x000a0000-0x000a07ff] >>> >>> as reported by Andy Isaacson at http://lkml.org/lkml/2010/4/6/375 >>> >>> I think the fact that the BAR is not within a host bridge window is a >>> BIOS defect, and it's now more visible because we have "pci=use_crs" as >>> the default. Using "pci=nocrs" is a workaround, because then we won't >>> attempt to move the device. >> >> that doesn't look right. >> >> It seem another thread, erission has one model without VGA, and they use that area for other device MMIO. >> >> current for 64bit, We remove [0xa0000, 0x100000) from e820 map if those area is E820_RAM. >> >> in e820_reserve_resources(), kernel will reserve range < 1M according to e820 map. >> that is before pci BAR is claimed. >> >> or you can add >> boot_params.screen_info.orig_video_isVGA == 1 >> or double check scan pci tree to see if video is there or not > > I'm sorry, I can't understand what you're saying. for 64 bit, you may check boot_params.screen_info.orig_video_isVGA to see if you need to reserve that VGA range. not sure if every bootloader fill that... > > It seems like you're saying we already have a mechanism to keep us > from assigning that VGA range to another device, but obviously it's > not working. > > Maybe it will be clearer if you propose a different patch that prevents > us from assigning 0xa0000 to the USB controller. when the system only have one peer root bus, can you skip the _CRS for it? YH -- 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
