On Fri, 09 Oct, at 06:51:34PM, Luck, Tony wrote: > > Current hardware can map one mirrored region from each memory controller. > We have two memory controllers per socket. So on a 4-socket machine we will > usually have 8 separate mirrored ranges. Two per NUMA node (assuming > cluster on die is not enabled). > > Practically I think it is safe to assume that any sane configuration will always > choose to mirror the <4GB range: > > 1) It's a trivial percentage of total memory on a system that supports mirror > (2GB[1] out of my, essentially minimal, 512GB[2] machine). So 0.4% ... why would > you not mirror it? > 2) It contains a bunch of things that you are likely to want mirrored. Currently > our boot loaders put the kernel there (don't they??). All sorts of BIOS space that > might be accessed at any time by SMI is there. Yeah, the bootloader and kernel image will most likely be in < 4GB region. That's not a hard requirement, and there's certainly support for loading things at higher addresses, but this low region is currently still preferred (see CONFIG_PHYSICAL_START). -- Matt Fleming, Intel Open Source Technology Center -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>