Re: [PATCH 1/6] riscv: hwprobe: Report FP extensions only when available

[guodong . xu]

Hi Radim,

On 2026-10-07 09:46, Radim Krčmář wrote:
> 2026-10-06T16:54:53-07:00, Charlie Jenkins <thecharlesjenkins@xxxxxxxxx>:
> > The vector Kconfig is gated on FPU=y so the vector instructions can't
> > ever be enabled when FPU=n.
>
> Right, I'll make the commit message clearer in v2.
> (Zve32x and hence has_vector() can technically exist without CONFIG_FPU,
> so future implementations might require use to remove the dependency.)

Do you mean dropping "depends on FPU" from RISCV_ISA_V? Today it reads
arch/riscv/Kconfig:

  config RISCV_ISA_V
          bool "Vector extension support"
          depends on TOOLCHAIN_HAS_V
          depends on FPU

Today that dependency also gates Zve32x, Zve64x, Zvbb, Zvbc and the Zvk*,
none of these touches floating-point state, but they are all being gated
by CONFIG_FPU, that seems not correct.

I noticed that the _validate() callbacks in today's cpufeature.c for these
non-F (non-D) related extensions are checked against V only, but that
doesn't change the fact that CONFIG_RISCV_ISA_V depends on CONFIG_FPU
(from a commit 3 years ago) in Kconfig.

I would agree with you that should be fixed.

BR,
Guodong