[PATCH v7 2/9] x86/resctrl: Require 64-bit x86 for resctrl support
From: Chen Yu
Date: Sat Aug 29 2026 - 02:08:33 EST
All known hardware that supports Intel RDT or AMD QoS is 64-bit. MMIO-based
Enhanced RDT (ERDT) monitoring requires readq()/writeq(), which are only
available on 64-bit.
32-bit x86 is maintained for legacy reasons. New CPU features are generally not
enabled for 32-bit systems, its test coverage keeps shrinking, and modern 32-bit
distributions have become rare. Discouraging the use of a 32-bit kernel is
discussed at:
https://lore.kernel.org/all/c6ab0c24-8931-4f0d-9be6-23498ab4c38b@xxxxxxxxx/
Drop 32-bit support by changing the X86_CPU_RESCTRL dependency from X86 to
X86_64.
Since X86_CPU_RESCTRL now implies X86_64, remove the redundant X86_64 dependency
from X86_CPU_RESCTRL_INTEL_AET.
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
Tested-by: Hongyu Ning <hongyu.ning@xxxxxxxxxxxxxxx>
---
v6->v7:
Replace the inaccurate "no realistic server use case" rationale with
the legacy, shrinking test coverage and rare distro reasoning.
(Reinette Chatre, Tony Luck, Dave Hansen, Borislav Petkov, Peter Zijlstra)
---
arch/x86/Kconfig | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index bdad90f210e4..6685e120cff3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -514,7 +514,7 @@ config X86_MPPARSE
config X86_CPU_RESCTRL
bool "x86 CPU resource control support"
- depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
+ depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
depends on MISC_FILESYSTEMS
select ARCH_HAS_CPU_RESCTRL
select RESCTRL_FS
@@ -537,7 +537,7 @@ config X86_CPU_RESCTRL
config X86_CPU_RESCTRL_INTEL_AET
bool "Intel Application Energy Telemetry"
- depends on X86_64 && X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
+ depends on X86_CPU_RESCTRL && CPU_SUP_INTEL && INTEL_PMT_TELEMETRY=y && INTEL_TPMI=y
help
Enable per-RMID telemetry events in resctrl.
--
2.25.1