On Wed, 19 Aug 2026 09:24:21 +0200 Thomas Weißschuh
<[email protected]> wrote:
> The removal of the architecture-specific asm/timex.h was meant to fall
> back to asm-generic/timex.h. However on UML, the host architecture
> headers are earlier on the include path and therefore asm/timex.h from
> the host architecture is used.
> On x86 that header in turn requires the generation of cpufeaturemasks.h,
> which is not set up for UML and the build fails.
>
> In file included from ../arch/x86/include/asm/tsc.h:9,
> from ../arch/x86/include/asm/timex.h:6,
> from ../include/linux/timex.h:67,
> from ../include/linux/time32.h:13,
> from ../include/linux/time.h:60,
> from ../include/linux/jiffies.h:10,
> from ../include/linux/ktime.h:25,
> from ../include/linux/timer.h:6,
> from ../include/linux/uprobes.h:18,
> from ../include/linux/mm_types.h:16,
> from ../include/linux/mmzone.h:22,
> from ../include/linux/gfp.h:7,
> from ../include/linux/slab.h:17,
> from ../include/linux/crypto.h:18,
> from ../arch/um/kernel/asm-offsets.c:6:
> arch/x86/include/asm/tsc.h: In function ‘get_cycles’:
> arch/um/include/asm/cpufeature.h:52:39: error: implicit declaration of
> function ‘DISABLED_MASK_BIT_SET’ [-Wimplicit-function-declaration]
> 52 | (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0
> : _static_cpu_has(bit))
> | ^~~~~~~~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro
> ‘cpu_feature_enabled’
> 79 | if (!cpu_feature_enabled(X86_FEATURE_TSC))
> | ^~~~~~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:115:17: error: implicit declaration of
> function ‘_static_cpu_has’ [-Wimplicit-function-declaration]
> 115 | _static_cpu_has(bit) \
> | ^~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro
> ‘_static_cpu_has’
> 52 | (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0
> : _static_cpu_has(bit))
> |
> ^~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro
> ‘cpu_feature_enabled’
> 79 | if (!cpu_feature_enabled(X86_FEATURE_TSC))
> | ^~~~~~~~~~~~~~~~~~~
> arch/um/include/asm/cpufeature.h:115:17: note: ‘_static_cpu_has’ is a
> function-like macro and might be used incorrectly
> arch/um/include/asm/cpufeature.h:52:72: note: in expansion of macro
> ‘_static_cpu_has’
> 52 | (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0
> : _static_cpu_has(bit))
> |
> ^~~~~~~~~~~~~~~
> arch/x86/include/asm/tsc.h:79:14: note: in expansion of macro
> ‘cpu_feature_enabled’
> 79 | if (!cpu_feature_enabled(X86_FEATURE_TSC))
> | ^~~~~~~~~~~~~~~~~~~
>
> The x86-specific timex.h also doesn't make sense on UML in general.
>
> Reintroduce the UML-specific asm/timex.h and add a comment to document
> its necessity.
I got the same issue, and confirmed this patch fixes it on my setup. Thank you
for sharing this patch.
>
> Fixes: 3ed403bbc967 ("treewide: Remove CLOCK_TICK_RATE")
> Signed-off-by: Thomas Weißschuh <[email protected]>
Tested-by: SJ Park <[email protected]>
Thanks,
SJ
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