On Sun, Dec 22, 2013 at 5:14 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > On Sun, Dec 22, 2013 at 4:00 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: >> On Thu, Dec 19, 2013 at 1:44 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: >> >> Let me see if I can figure out what you're trying to do here. Please >> correct me if I'm wrong: >> >>> When one of children resources does not support MEM_64, MEM_64 for >>> bridge get reset, so pull down whole pref resource on the bridge under 4G. >> >> When we allocate space for a bridge's prefetchable window, we >> currently look at the devices behind the bridge and put the window >> below 4GB if any of those children has a 32-bit prefetchable BAR. >> >> This maximizes the use of prefetch, at the cost of using more 32-bit >> address space. > > yes. and we have problem when we have 8 sockets or 32 sockets system, > will have limit 32bit space. > but we have enough above 4G 64bit mmio for prefetchable. > >> >>> If the bridge support pref mem 64, will only allocate that with pref mem64 to >>> children that support it. >>> For children resources if they only support pref mem 32, will allocate them >>> from non pref mem instead. >> >> You are changing this so that we will always try to put a bridge's >> 64-bit prefetchable window above 4GB, regardless of what devices are >> behind the bridge. If a device behind the bridge has a 32-bit >> prefetchable BAR, we will place that BAR in the bridge's 32-bit >> non-prefetchable window. > > Yes. so we can keep IORESOURCE_MEM64 in the flags for PREF. > >> >> This minimizes the use of the 32-bit address space, at the cost of not >> being able to use prefetch as much. >> >>> If the bridge only support 32bit pref mmio, will still have all children pref >>> mmio under that. >> >> Obviously, if a bridge has a prefetchable window that's only 32 bits, >> 64-bit prefetchable BARs behind the bridge will have to be in that >> 32-bit prefetchable window or the 32-bit non-prefetchable window. And >> if the bridge has no prefetchable window at all, every memory BAR >> behind the bridge will have to be in the 32-bit non-prefetchable >> window. > > Yes. > >> >> I'll look at the actual patch later; I just want to make sure I >> understand your intent first. Hi, Bjorn, Can you check and add this one to your pci/resource branch? With that we can close the loop for 64bit mmio resource allocation. Thanks Yinghai -- 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
