Messages in this thread | | | Date | Wed, 25 May 2011 13:43:11 +0100 | Subject | Re: [PATCH v6 00/18] ARM: Add support for the Large Physical Address Extensions | From | Catalin Marinas <> |
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On 25 May 2011 12:22, Catalin Marinas <catalin.marinas@arm.com> wrote: > On Wed, 2011-05-25 at 12:10 +0100, Arnd Bergmann wrote: >> On Wednesday 25 May 2011, Nicolas Pitre wrote: >> > > Do you expect non LPAE targets to be able to boot with these changes >> > > applied (and LPAE enabled)? I am able to build this tree for the >> > > MSM8660 (with a minor patch below), but it fails to boot with LPAE >> > > enabled. It seems to work fine with LPAE not enabled. >> > >> > I wouldn't expect a LPAE kernel to boot on non LPAE capable hardware. >> > >> > And I don't think we'll ever try to support both LPAE and non-LPAE modes >> > in the same kernel binary either since this has implications all over >> > the place in core kernel mm code. >> >> Just for information and to complete the picture, what other of these >> combinations are possible? >> >> * Non-LPAE kernel on LPAE-capable hardware > > Works fine. The LPAE-capable processors like A15 support the classic > page table format as well, it's only a configuration bit to switch to > LPAE. > >> * LPAE kernel as KVM guest of LPAE kernel > > Should work when KVM for A15 becomes available > >> * non-LPAE kernel as KVM guest of LPAE kernel > > Same as above. KVM shouldn't care much about the underlying OS, it just > sets up the IPA (Intermediate Physical Address) translations and you can > have classic page tables on top.
Just a clarification here - KVM with support for LPAE also requires the virtualisation extensions (which are present in Cortex-A15). The virtualisation extensions require LPAE in hardware but I'm not sure the opposite is true.
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