[tip: x86/cpu] x86/cpu: Remove unused !CONFIG_X86_TSC code
From: tip-bot2 for Ingo Molnar
Date: Thu Jun 11 2026 - 04:36:30 EST
The following commit has been merged into the x86/cpu branch of tip:
Commit-ID: 5c75b98aa9cd5b1725b76999d794dc72ebd7a54a
Gitweb: https://git.kernel.org/tip/5c75b98aa9cd5b1725b76999d794dc72ebd7a54a
Author: Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate: Mon, 27 Apr 2026 08:07:02 +02:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Thu, 11 Jun 2026 10:25:34 +02:00
x86/cpu: Remove unused !CONFIG_X86_TSC code
Now that the Kconfig space always enables CONFIG_X86_TSC (on x86),
remove !CONFIG_X86_TSC code from the x86 arch code.
We still keep the Kconfig option to catch any eventual code still
pending in maintainer or non-mainline trees, plus some drivers
have raw TSC timestamping hacks that use CONFIG_X86_TSC.
It's also still possible to disable TSC support runtime.
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ahmed S . Darwish <darwi@xxxxxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: H . Peter Anvin <hpa@xxxxxxxxx>
Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250425084216.3913608-13-mingo@xxxxxxxxxx
---
arch/x86/include/asm/timex.h | 3 +--
arch/x86/include/asm/trace_clock.h | 8 --------
arch/x86/include/asm/tsc.h | 13 +------------
arch/x86/kernel/Makefile | 4 ++--
arch/x86/kernel/i8253.c | 2 +-
arch/x86/kernel/tsc.c | 13 -------------
6 files changed, 5 insertions(+), 38 deletions(-)
diff --git a/arch/x86/include/asm/timex.h b/arch/x86/include/asm/timex.h
index 956e414..6e57e3c 100644
--- a/arch/x86/include/asm/timex.h
+++ b/arch/x86/include/asm/timex.h
@@ -7,8 +7,7 @@
static inline unsigned long random_get_entropy(void)
{
- if (!IS_ENABLED(CONFIG_X86_TSC) &&
- !cpu_feature_enabled(X86_FEATURE_TSC))
+ if (!cpu_feature_enabled(X86_FEATURE_TSC))
return random_get_entropy_fallback();
return rdtsc();
}
diff --git a/arch/x86/include/asm/trace_clock.h b/arch/x86/include/asm/trace_clock.h
index 7061a56..1efab28 100644
--- a/arch/x86/include/asm/trace_clock.h
+++ b/arch/x86/include/asm/trace_clock.h
@@ -5,17 +5,9 @@
#include <linux/compiler.h>
#include <linux/types.h>
-#ifdef CONFIG_X86_TSC
-
extern u64 notrace trace_clock_x86_tsc(void);
# define ARCH_TRACE_CLOCKS \
{ trace_clock_x86_tsc, "x86-tsc", .in_ns = 0 },
-#else /* !CONFIG_X86_TSC */
-
-#define ARCH_TRACE_CLOCKS
-
-#endif
-
#endif /* _ASM_X86_TRACE_CLOCK_H */
diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 4f7f09f..4d2d2f2 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -76,8 +76,7 @@ extern void disable_TSC(void);
static inline cycles_t get_cycles(void)
{
- if (!IS_ENABLED(CONFIG_X86_TSC) &&
- !cpu_feature_enabled(X86_FEATURE_TSC))
+ if (!cpu_feature_enabled(X86_FEATURE_TSC))
return 0;
return rdtsc();
}
@@ -94,25 +93,15 @@ extern unsigned long native_calibrate_tsc(void);
extern unsigned long long native_sched_clock_from_tsc(u64 tsc);
extern int tsc_clocksource_reliable;
-#ifdef CONFIG_X86_TSC
extern bool tsc_async_resets;
-#else
-# define tsc_async_resets false
-#endif
/*
* Boot-time check whether the TSCs are synchronized across
* all CPUs/cores:
*/
-#ifdef CONFIG_X86_TSC
extern bool tsc_store_and_check_tsc_adjust(bool bootcpu);
extern void tsc_verify_tsc_adjust(bool resume);
extern void check_tsc_sync_target(void);
-#else
-static inline bool tsc_store_and_check_tsc_adjust(bool bootcpu) { return false; }
-static inline void tsc_verify_tsc_adjust(bool resume) { }
-static inline void check_tsc_sync_target(void) { }
-#endif
extern int notsc_setup(char *);
extern void tsc_save_sched_clock_state(void);
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 47a32f5..31f46fd 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -108,7 +108,7 @@ apm-y := apm_32.o
obj-$(CONFIG_APM) += apm.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_SMP) += smpboot.o
-obj-$(CONFIG_X86_TSC) += tsc_sync.o
+obj-y += tsc_sync.o
obj-$(CONFIG_SMP) += setup_percpu.o
obj-$(CONFIG_X86_MPPARSE) += mpparse.o
obj-y += apic/
@@ -117,7 +117,7 @@ obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
obj-$(CONFIG_FUNCTION_TRACER) += ftrace_$(BITS).o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
-obj-$(CONFIG_X86_TSC) += trace_clock.o
+obj-y += trace_clock.o
obj-$(CONFIG_TRACING) += trace.o
obj-$(CONFIG_RETHOOK) += rethook.o
obj-$(CONFIG_VMCORE_INFO) += vmcore_info_$(BITS).o
diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c
index cb9852a..0b99103 100644
--- a/arch/x86/kernel/i8253.c
+++ b/arch/x86/kernel/i8253.c
@@ -31,7 +31,7 @@ struct clock_event_device *global_clock_event;
*/
static bool __init use_pit(void)
{
- if (!IS_ENABLED(CONFIG_X86_TSC) || !boot_cpu_has(X86_FEATURE_TSC))
+ if (!boot_cpu_has(X86_FEATURE_TSC))
return true;
/* This also returns true when APIC is disabled */
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index c5110eb..ce10ae4 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -298,30 +298,17 @@ notrace u64 sched_clock(void)
preempt_enable_notrace();
return now;
}
-
int check_tsc_unstable(void)
{
return tsc_unstable;
}
EXPORT_SYMBOL_GPL(check_tsc_unstable);
-#ifdef CONFIG_X86_TSC
int __init notsc_setup(char *str)
{
mark_tsc_unstable("boot parameter notsc");
return 1;
}
-#else
-/*
- * disable flag for tsc. Takes effect by clearing the TSC cpu flag
- * in cpu/common.c
- */
-int __init notsc_setup(char *str)
-{
- setup_clear_cpu_cap(X86_FEATURE_TSC);
- return 1;
-}
-#endif
__setup("notsc", notsc_setup);
enum {