Messages in this thread | | | From | George Pee <> | Date | Fri, 9 Sep 2022 08:35:07 -0500 | Subject | Re: [PATCH] Report support for optional ARMv8.2 half-precision floating point extension |
| |
The use case is really being able to tell, from userspace on a 32-bit kernel, if FPHP is supported. It's really just reporting for convenience.
It wasn't clear to me why HWCAP2 was used in some cases and not others. I can add FPHP to HWCAP2 if that's the right thing to do here.
On Fri, Sep 9, 2022 at 6:39 AM Catalin Marinas <catalin.marinas@arm.com> wrote: > > On Thu, Sep 01, 2022 at 09:13:05AM -0500, george pee wrote: > > Report as fphp to be consistent with arm64 > > Do you have a use-case as well? It may help deciding what to do with > this. > > > diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h > > index 990199d8b7c6..f975845ce5d3 100644 > > --- a/arch/arm/include/uapi/asm/hwcap.h > > +++ b/arch/arm/include/uapi/asm/hwcap.h > > @@ -28,6 +28,7 @@ > > #define HWCAP_IDIV (HWCAP_IDIVA | HWCAP_IDIVT) > > #define HWCAP_LPAE (1 << 20) > > #define HWCAP_EVTSTRM (1 << 21) > > +#define HWCAP_FPHP (1 << 22) > > I think with ARMv8 features on the arm32 kernel we tend to add them to > HWCAP2_*. With such change: > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> > > I'll leave the decision to Russell on whether he wants this merged. An > argument may be that people still want to run 32-bit user-space and even > if they use am arm64 kernel, we can't add a COMPAT_HWCAP2_FPHP until we > have the arm32 counterpart. An alternative may be to only add the uapi > definition under arch/arm but without any functionality (so never > exposed to user). The arm64 kernel could expose it to compat tasks. > > So, if Russell is ok with any of the options above, please also add the > compat arm64 support ;). > > -- > Catalin
| |