x86/Kconfig: Limit NR_CPUS on 32-bit to a sane amount

The recent cpu_entry_area changes fail to compile on 32-bit when BIGSMP=y and NR_CPUS=512, because the fixmap area becomes too big. Limit the number of CPUs with BIGSMP to 64, which is already way to big for 32-bit, but it's at least a working limitation. We performed a quick survey of 32-bit-only machines that might be affected by this change negatively, but found none. Signed-off-by: Thomas Gleixner <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Juergen Gross <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: [email protected] Signed-off-by: Ingo Molnar <[email protected]>
chewitt · Dec 22, 2017 · 7bbcbd3 · 7bbcbd3
1 parent 6cbd217
commit 7bbcbd3
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
@@ -925,7 +925,8 @@ config MAXSMP
 config NR_CPUS
 	int "Maximum number of CPUs" if SMP && !MAXSMP
 	range 2 8 if SMP && X86_32 && !X86_BIGSMP
-	range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
+	range 2 64 if SMP && X86_32 && X86_BIGSMP
+	range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK && X86_64
 	range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
 	default "1" if !SMP
 	default "8192" if MAXSMP