arm64: 36 bit VA
36bit VA lets us use 2 level page tables while limiting the
available address space to 64GB.
Cc: Will Deacon <will.deacon@arm.com>
Cc: Steve Capper <steve.capper@linaro.org>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 8541664..a346671 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -170,6 +170,7 @@
config PGTABLE_LEVELS
int
+ default 2 if ARM64_16K_PAGES && ARM64_VA_BITS_36
default 2 if ARM64_64K_PAGES && ARM64_VA_BITS_42
default 3 if ARM64_64K_PAGES && ARM64_VA_BITS_48
default 3 if ARM64_4K_PAGES && ARM64_VA_BITS_39
@@ -391,6 +392,10 @@
space sizes. The level of translation table is determined by
a combination of page size and virtual address space size.
+config ARM64_VA_BITS_36
+ bool "36-bit"
+ depends on ARM64_16K_PAGES
+
config ARM64_VA_BITS_39
bool "39-bit"
depends on ARM64_4K_PAGES
@@ -410,6 +415,7 @@
config ARM64_VA_BITS
int
+ default 36 if ARM64_VA_BITS_36
default 39 if ARM64_VA_BITS_39
default 42 if ARM64_VA_BITS_42
default 47 if ARM64_VA_BITS_47
@@ -480,7 +486,7 @@
def_bool y
config ARCH_WANT_HUGE_PMD_SHARE
- def_bool y if ARM64_4K_PAGES || ARM64_16K_PAGES
+ def_bool y if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)
config HAVE_ARCH_TRANSPARENT_HUGEPAGE
def_bool y
