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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
