Re: [PATCH] x86/Kconfig: Fix dependency for X86_DEBUG_FPU

From: Ingo Molnar
Date: Thu Apr 10 2025 - 02:34:13 EST



* Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:

> Yes it is vanilla

Thx.

> > More importantly, X86_REQUIRED_FEATURE_FPU *does not exist* in the
> > vanilla v6.14 kernel, it's a new v6.15 feature. So this part of
> > your changelog totally doesn't apply to a v6.14 kernel:
>
> I started with vanilla 6.14 kernel running oldconfig on it. In this
> case if X86_DEBUG_FPU is enabled in the oldconfig, should the config
> generated for 6.15 add X86_REQUIRED_FEATURE_FPU.
>
> It appears there is a dependency between X86_DEBUG_FPU and the newly
> added X86_REQUIRED_FEATURE_FPU

Could you send the v6.15-rc1 config that has this missing dependency?

Because if I put the config you sent through 'make oldconfig' and
accept all default suggestions, the X86_REQUIRED_FEATURE_FPU dependency
is present:

starship:~/tip> grep _FPU .config
CONFIG_X86_REQUIRED_FEATURE_FPU=y
CONFIG_ARCH_HAS_KERNEL_FPU_SUPPORT=y
CONFIG_X86_DEBUG_FPU=y
# CONFIG_TEST_FPU is not set

... and the build succeeds:

OBJCOPY arch/x86/boot/setup.bin
BUILD arch/x86/boot/bzImage
Kernel: arch/x86/boot/bzImage is ready (#4)

Ie. I cannot reproduce the build failure with the config you provided.

Thanks,

Ingo