x32: Allow x32 to be configured
At this point, one should be able to build an x32 kernel.
Note that for now we depend on CONFIG_IA32_EMULATION. Long term, x32
and IA32 should be detangled.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5bed94e1..c9d6c9e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2165,9 +2165,9 @@
depends on X86_64
select COMPAT_BINFMT_ELF
---help---
- Include code to run 32-bit programs under a 64-bit kernel. You should
- likely turn this on, unless you're 100% sure that you don't have any
- 32-bit programs left.
+ Include code to run legacy 32-bit programs under a
+ 64-bit kernel. You should likely turn this on, unless you're
+ 100% sure that you don't have any 32-bit programs left.
config IA32_AOUT
tristate "IA32 a.out support"
@@ -2175,9 +2175,22 @@
---help---
Support old a.out binaries in the 32bit emulation.
+config X86_X32_ABI
+ bool "x32 ABI for 64-bit mode (EXPERIMENTAL)"
+ depends on X86_64 && IA32_EMULATION && EXPERIMENTAL
+ ---help---
+ Include code to run binaries for the x32 native 32-bit ABI
+ for 64-bit processors. An x32 process gets access to the
+ full 64-bit register file and wide data path while leaving
+ pointers at 32 bits for smaller memory footprint.
+
+ You will need a recent binutils (2.22 or later) with
+ elf32_x86_64 support enabled to compile a kernel with this
+ option set.
+
config COMPAT
def_bool y
- depends on IA32_EMULATION
+ depends on IA32_EMULATION || X86_X32_ABI
config COMPAT_FOR_U64_ALIGNMENT
def_bool COMPAT