linux-kernel - [PATCH] arch/x86: Encourage rather than discourage x2apic support

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Date:   Wed, 31 Mar 2021 05:16:41 +0000
From:   Luke Dashjr <luke@...hjr.org>
To:     linux-kernel@...r.kernel.org, trivial@...nel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
Subject: [PATCH] arch/x86: Encourage rather than discourage x2apic support

Multi-core SMP doesn't work on modern Intel CPUs (at least Comet Lake) without
x2apic. Unsure users should say Y.
    
Signed-off-by: Luke Dashjr <luke-jr+git@...pios.org>
---
 arch/x86/Kconfig | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2792879d398ee..ddb42707bd069 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -446,9 +446,10 @@ config X86_X2APIC
          This enables x2apic support on CPUs that have this feature.
 
          This allows 32-bit apic IDs (so it can support very large systems),
-         and accesses the local apic via MSRs not via mmio.
+         and accesses the local apic via MSRs not via mmio. It is also needed
+         to use multiple cores on modern Intel CPUs.
 
-         If you don't know what to do here, say N.
+         If you don't know what to do here, say Y.
 
 config X86_MPPARSE
        bool "Enable MPS table" if ACPI
--
2.6.23