* Shuah Khan <skhan@linuxfoundation.org> wrote:

> Compile fails when X86_DEBUG_FPU is enabled and X86_REQUIRED_FEATURE_FPU is
> disabled. Add explicit dependency on X86_REQUIRED_FEATURE_FPU to fix it.
> 
> ../arch/x86/kernel/fpu/regset.c:411:(.text+0x4cf2f): undefined reference to `fpregs_soft_get'
> ld: vmlinux.o: in function `fpregs_set':
> ../arch/x86/kernel/fpu/regset.c:445:(.text+0x4d0da): undefined reference to `fpregs_soft_set'
> ld: vmlinux.o: in function `copy_fpstate_to_sigframe':
> ../arch/x86/kernel/fpu/signal.c:197:(.text+0x4da98): undefined reference to `fpregs_soft_get'
> 

So I cannot reproduce this build failure on either v6.14 or v6.15-rc1:

  starship:~/tip> git describe
  v6.15-rc1

  starship:~/tip> grep -E 'X86_32=|M486SX=|X86_REQUIRED_FEATURE|X86_DEBUG_FPU' .config
  CONFIG_X86_32=y
  CONFIG_M486SX=y
  CONFIG_X86_REQUIRED_FEATURE_ALWAYS=y
  CONFIG_X86_DEBUG_FPU=y

  starship:~/tip> make -j128 ARCH=i386 bzImage modules

  ...
  Kernel: arch/x86/boot/bzImage is ready  (#5)

> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
> ---
> 6.14 compile worked without X86_REQUIRED_FEATURE_FPU enabled. Might be a
> new dependency. Enabling X86_REQUIRED_FEATURE_FPU fixed it for me on my
> test system.

So vanilla v6.14 does not have X86_REQUIRED_FEATURE Kconfig flags, at 
all:

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

Because X86_REQUIRED_FEATURE_FPU is a new v6.15-rc1 feature, introduced 
via:

  3d37d9396eb3 ("x86/cpufeatures: Add {REQUIRED,DISABLED} feature configs")

I have no doubt you are seeing this build failure - but I think there 
might be some other .config detail required to reproduce it, not 
mentioned in your changelog. Could you please send the config you used?

Thanks,

	Ingo