From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA8A1ECAAA1 for ; Fri, 9 Sep 2022 11:40:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230150AbiIILkQ (ORCPT ); Fri, 9 Sep 2022 07:40:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231318AbiIILjl (ORCPT ); Fri, 9 Sep 2022 07:39:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA7871CD for ; Fri, 9 Sep 2022 04:39:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4531961FC5 for ; Fri, 9 Sep 2022 11:39:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 066AFC433D7; Fri, 9 Sep 2022 11:39:19 +0000 (UTC) Date: Fri, 9 Sep 2022 12:39:16 +0100 From: Catalin Marinas To: george pee Cc: Russell King , "Russell King (Oracle)" , "Kirill A. Shutemov" , Austin Kim , Ard Biesheuvel , Mike Rapoport , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Report support for optional ARMv8.2 half-precision floating point extension Message-ID: References: <20220901141307.2361752-1-georgepee@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220901141307.2361752-1-georgepee@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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