linux-kernel - [PATCH] x86: Disable HIGHMEM64G selection for M486SX

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Date:   Wed, 14 Apr 2021 12:38:28 +0200 (CEST)
From:   "Maciej W. Rozycki" <macro@...am.me.uk>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] x86: Disable HIGHMEM64G selection for M486SX

Fix a regression caused by making the 486SX a separate processor family, 
for which the HIGHMEM64G setting has not been updated and therefore has 
become exposed as a user selectable option for the M486SX configuration 
setting unlike with original M486 and all the other settings that choose 
non-PAE-enabled processors:

High Memory Support
> 1. off (NOHIGHMEM)
  2. 4GB (HIGHMEM4G)
  3. 64GB (HIGHMEM64G)
choice[1-3?]:

With the fix in place the setting is now correctly removed:

High Memory Support
> 1. off (NOHIGHMEM)
  2. 4GB (HIGHMEM4G)
choice[1-2?]:

Signed-off-by: Maciej W. Rozycki <macro@...am.me.uk>
Fixes: 87d6021b8143 ("x86/math-emu: Limit MATH_EMULATION to 486SX compatibles")
Cc: stable@...r.kernel.org # v5.5+
---
 arch/x86/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

linux-x86-highmem64g-m486sx.diff
Index: linux-macro-ide/arch/x86/Kconfig
===================================================================
--- linux-macro-ide.orig/arch/x86/Kconfig
+++ linux-macro-ide/arch/x86/Kconfig
@@ -1406,7 +1406,7 @@ config HIGHMEM4G
 
 config HIGHMEM64G
 	bool "64GB"
-	depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
+	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
 	select X86_PAE
 	help
 	  Select this if you have a 32-bit processor and more than 4