Messages in this thread | | | Date | Fri, 23 Nov 2012 09:56:52 +0000 | From | "Jan Beulich" <> | Subject | Re: [PATCH v2 01/11] kexec: introduce kexec_ops struct |
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>>> On 22.11.12 at 18:37, "H. Peter Anvin" <hpa@zytor.com> wrote: > I actually talked to Ian Jackson at LCE, and mentioned among other > things the bogosity of requiring a PUD page for three-level paging in > Linux -- a bogosity which has spread from Xen into native. It's a page > wasted for no good reason, since it only contains 32 bytes worth of > data, *inherently*. Furthermore, contrary to popular belief, it is > *not* pa page table per se. > > Ian told me: "I didn't know we did that, and we shouldn't have to." > Here we have suffered this overhead for at least six years, ...
Even the Xen kernel only needs the full page when running on a 64-bit hypervisor (now that we don't have a 32-bit hypervisor anymore, that of course basically means always). But yes, I too never liked this enforced over-allocation for native kernels (and was surprised that it was allowed in at all).
Jan
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