On Mon, Oct 23, 2017 at 01:56:58PM +0200, Ingo Molnar wrote: > > * Kirill A. Shutemov <kir...@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
