diff options
| author | Steve Capper <steve.capper@arm.com> | 2018-12-06 22:50:42 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2018-12-10 18:42:18 +0000 |
| commit | b9567720a1b8e739380e0241413606c056c57859 (patch) | |
| tree | 760f658f0fbb3ec46f0cbdaa0314245f6f094fb7 /arch/arm64/Kconfig | |
| parent | 67e7fdfcc6824a4f768d76d89377b33baad58fad (diff) | |
arm64: mm: Allow forcing all userspace addresses to 52-bit
On arm64 52-bit VAs are provided to userspace when a hint is supplied to
mmap. This helps maintain compatibility with software that expects at
most 48-bit VAs to be returned.
In order to help identify software that has 48-bit VA assumptions, this
patch allows one to compile a kernel where 52-bit VAs are returned by
default on HW that supports it.
This feature is intended to be for development systems only.
Signed-off-by: Steve Capper <steve.capper@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 858e353b2f40..ca1f93233b22 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1186,6 +1186,19 @@ config ARM64_CNP at runtime, and does not affect PEs that do not implement this feature. +config ARM64_FORCE_52BIT + bool "Force 52-bit virtual addresses for userspace" + depends on ARM64_52BIT_VA && EXPERT + help + For systems with 52-bit userspace VAs enabled, the kernel will attempt + to maintain compatibility with older software by providing 48-bit VAs + unless a hint is supplied to mmap. + + This configuration option disables the 48-bit compatibility logic, and + forces all userspace addresses to be 52-bit on HW that supports it. One + should only enable this configuration option for stress testing userspace + memory management code. If unsure say N here. + endmenu config ARM64_SVE |