[PATCH v14 22/24] x86/resctrl: Require 64-bit x86 for resctrl support

[Tony Luck]

Intel Application Energy Telemetry (AET) provides event counts in 64-bit
MMIO registers. For accurate results these must be read with a single
64-bit load, which is only available to 64-bit kernels, so AET support
depends on X86_64.

AET is about to become an unconditional part of x86 resctrl instead of
being selected by the separate CONFIG_X86_CPU_RESCTRL_INTEL_AET option.
resctrl can then no longer be built for 32-bit kernels.

Make resctrl depend on X86_64, in preparation for removing
CONFIG_X86_CPU_RESCTRL_INTEL_AET. This drops resctrl support from 32-bit
kernels, in line with Dave Hansen's proposal [1] to document reduced
support for 32-bit x86. Keeping support for 32-bit kernels is not
worth it. Modern systems that support resctrl almost always have more
memory than can be addressed by a 32-bit Linux kernel.

Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Link: https://lore.kernel.org/all/c6ab0c24-8931-4f0d-9be6-23498ab4c38b@xxxxxxxxx/ # [1]
---
v14:
	New commit message.
---
 arch/x86/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 15fd9ec5ecac..06b5d0c4633e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -518,7 +518,7 @@ 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
@@ -541,7 +541,7 @@ 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.
 
-- 
2.56.0