Messages in this thread |  | | Date | Mon, 23 Oct 2017 15:21:59 +0300 | | From | "Kirill A. Shutemov" <> | | Subject | Re: [PATCH 0/6] Boot-time switching between 4- and 5-level paging for 4.15, Part 1 |
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On Mon, Oct 23, 2017 at 01:56:58PM +0200, Ingo Molnar wrote: > > * Kirill A. Shutemov <kirill@shutemov.name> wrote: > > > > Or, could we keep MAX_PHYSMEM_BITS constant, and introduce a _different_ constant > > > that is dynamic, and which could be used in the cases where the 5-level paging > > > config causes too much memory footprint in the common 4-level paging case? > > > > This is more labor intensive case with unclear benefit. > > > > Dynamic MAX_PHYSMEM_BITS doesn't cause any issue in wast majority of > > cases. > > Almost nothing uses it - and even in those few cases it caused problems.
It's used in many places indirectly. See MAXMEM.
> Making a variable that 'looks' like a constant macro dynamic in a rare Kconfig > scenario is asking for trouble.
We expect boot-time page mode switching to be enabled in kernel of next generation enterprise distros. It shoudn't be that rare.
-- Kirill A. Shutemov
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