On 10 October 2017 at 15:56, Marcin Wojtas <[email protected]> wrote: > Hi Ard, > > 2017-10-10 16:53 GMT+02:00 Leif Lindholm <[email protected]>: >> On Mon, Oct 09, 2017 at 07:00:57PM +0200, Marcin Wojtas wrote: >>> From: Ard Biesheuvel <[email protected]> >>> >>> The GIC architecture mandates that the CPU interface, which consists >>> of 2 consecutive 4 KB frames, can be mapped using separate mappings. >>> Since this is problematic on 64 KB pages, the MMU-400 aliases each >>> frame 16 times, and the two consecutive frames can be found at offset >>> 0xf000. This patch is intended to expose correct GICC alias via >>> MADT, once ACPI support is added. >> >> I'm afraid I don't quite understand this message. >> >> The change seems to be that the InterfaceBase moves from the first 4KB >> alias inside a 64KB page to the last alias within the same page. >> That seems valid, but I don't see how it resolves anything described >> in this message? >>
Because now, GICC + 4 KB will point at the second frame, and so the two frames appear adjacently, and precisely 4 KB apart. And at the same time, they are still covered by distinct 64 KB pages so it even works when running the OS with 64k pages. _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
