Currently ZONE_DEVICE depends on X86_64. This is fine for now, but it
will get unwieldly as new platforms get ZONE_DEVICE support. Moving it
to an arch selected Kconfig option to save us some trouble in the
future.

Cc: x86@kernel.org
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
---
 arch/x86/Kconfig | 1 +
 mm/Kconfig       | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cd18994a9555..acbb15234562 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig

@@ -59,6 +59,7 @@ config X86
        select ARCH_HAS_STRICT_KERNEL_RWX
        select ARCH_HAS_STRICT_MODULE_RWX
        select ARCH_HAS_UBSAN_SANITIZE_ALL
+       select ARCH_HAS_ZONE_DEVICE             if X86_64
        select ARCH_HAVE_NMI_SAFE_CMPXCHG
        select ARCH_MIGHT_HAVE_ACPI_PDC         if ACPI
        select ARCH_MIGHT_HAVE_PC_PARPORT

diff --git a/mm/Kconfig b/mm/Kconfig
index beb7a455915d..2d38a4abe957 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig

@@ -683,12 +683,15 @@ config IDLE_PAGE_TRACKING

          See Documentation/vm/idle_page_tracking.txt for more details.

+config ARCH_HAS_ZONE_DEVICE
+       def_bool n
+
 config ZONE_DEVICE
        bool "Device memory (pmem, etc...) hotplug support"
        depends on MEMORY_HOTPLUG
        depends on MEMORY_HOTREMOVE
        depends on SPARSEMEM_VMEMMAP
-       depends on X86_64 #arch_add_memory() comprehends device memory
+       depends on ARCH_HAS_ZONE_DEVICE

        help
          Device memory hotplug support allows for establishing pmem,