>>> On 30.05.17 at 16:57, <jgr...@suse.com> wrote: > On 30/05/17 12:43, Jan Beulich wrote: >>>>> On 30.05.17 at 12:33, <jgr...@suse.com> wrote: >>> On 30/05/17 09:24, Jan Beulich wrote: >>>> But if the OS allocated large pages internally for relevant data >>>> structures, those obviously won't come from that necessarily 4k- >>>> mapped tail range. >>> >>> Sure? I think the kernel is using 1GB pages if possible for direct >>> kernel mappings of the physical memory. It doesn't care for the last >>> page mapping some space not populated. >> >> Are you sure? I would very much hope for Linux to not establish >> mappings to addresses where no memory (and no MMIO) resides. >> But I can't tell for sure for recent Linux versions; I do know in the >> old days they were quite careful there. > > Looking at phys_pud_init() they are happily using 1GB pages until they > have all memory mapped.
It's the layers higher up which I think make sure to call this with bit PG_LEVEL_1G set only when covering all RAM (see split_mem_range()). Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
