On 12/15/2010 10:18 AM, Bjorn Helgaas wrote: > > ACPI devices tend to be at high addresses, so allocating top-down > is definitely more dangerous unless we explicitly avoid them. I > should have realized that and done something like patches 1-3 of > this series before the top-down patches. > > Doing it bottom-up would very likely work better than the "top-down > without avoiding ACPI regions" model we currently have, at least in > the short term. We *would* have to do something to avoid E820 > reservations to fix this: > https://bugzilla.kernel.org/show_bug.cgi?id=16228, > but that's doable. > > So here's my proposal for .37: > - Keep the current state of _CRS enabled by default (for 2008 > and newer machines). > - Allocate bottom-up always > - Avoid E820 reservations > > That should fix all the regressions I'm aware of. I'll work on > the patches this afternoon. > At the same time, I would like to see a few things done as a matter of course: a) reserve the top 2 MiB of the 32-bit address space. There *will* be ROM at the top of the 32-bit address space; it's a fact of the architecture, and on at least older systems it was common to have a shadow 1 MiB below. b) we may want to consider doing special things in the 0xFExxxxxx memory range, which is used by the CPU-APIC-MSI system in recent processors. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- 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
