On 5 June 2017 at 09:08, Mark Rutland <mark.rutland@xxxxxxx> wrote: > On Mon, Jun 05, 2017 at 08:04:35AM +0000, Ard Biesheuvel wrote: >> On ARM, regions of memory that are described by UEFI as having special >> significance to the firmware itself are omitted from the linear mapping. >> This is necessary since we cannot guarantee that alternate mappings of >> the same physical region will use attributes that are compatible with >> the ones we use for the linear mapping, and aliases with mismatched >> attributes are prohibited by the architecture. >> >> The above does not apply to ACPI reclaim regions: such regions have no >> special significance to the firmware, and it is up to the OS to decide >> whether or not to preserve them after it has consumed their contents, >> and for how long, after which time the OS can use the memory in any way >> it likes. In the Linux case, such regions are preserved indefinitely, >> and are simply treated the same way as other 'reserved' memory types. >> >> Punching holes into the linear mapping causes page table fragmentation, >> which increases TLB pressure, and so we should avoid doing so if we can. >> So add a special case for regions of type EFI_ACPI_RECLAIM_MEMORY, and >> memblock_reserve() them instead of marking them MEMBLOCK_NOMAP. >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > > Sounds sane to me. FWIW: > > Acked-by: Mark Rutland <mark.rutland@xxxxxxx> > Thanks. I have queued this in efi/next -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
