The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     18ec1eaf58fbf2d9009a752a102a3d8e0d905a0f
Gitweb:        
https://git.kernel.org/tip/18ec1eaf58fbf2d9009a752a102a3d8e0d905a0f
Author:        Kirill A. Shutemov <[email protected]>
AuthorDate:    Fri, 13 Sep 2019 12:54:52 +03:00
Committer:     Ingo Molnar <[email protected]>
CommitterDate: Mon, 16 Sep 2019 16:51:20 +02:00

x86/mm: Enable 5-level paging support by default

Support of boot-time switching between 4- and 5-level paging mode is
upstream since 4.17.

We run internal testing with 5-level paging support enabled for a while
and it doesn't not cause any functional or performance regression on
4-level paging hardware.

The only 5-level paging related regressions I saw were in early boot
code that runs independently from CONFIG_X86_5LEVEL.

The next major release of distributions expected to have
CONFIG_X86_5LEVEL=y.

Enable the option by default. It may help to catch obscure bugs early.

Signed-off-by: Kirill A. Shutemov <[email protected]>
Acked-by: Dave Hansen <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link: 
https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 58eae28..d4bbebe 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1483,6 +1483,7 @@ config X86_PAE
 
 config X86_5LEVEL
        bool "Enable 5-level page tables support"
+       default y
        select DYNAMIC_MEMORY_LAYOUT
        select SPARSEMEM_VMEMMAP
        depends on X86_64

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