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 36CC8C433EF for ; Thu, 14 Apr 2022 12:02:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242987AbiDNMFN (ORCPT ); Thu, 14 Apr 2022 08:05:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242991AbiDNMFL (ORCPT ); Thu, 14 Apr 2022 08:05:11 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 689F5B1DF; Thu, 14 Apr 2022 05:02:45 -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 ams.source.kernel.org (Postfix) with ESMTPS id D557DB82930; Thu, 14 Apr 2022 12:02:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B367FC385A8; Thu, 14 Apr 2022 12:02:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1649937762; bh=8YmqxUbtiJbDtgg9GE40m6V0ysQjrfb2uFIJyqmLqcI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aKValRNE2RLplvHpyVdwwRamA2mKT9aTVateGdX2HoLuZagE+G5FXLXpoloKmXPbc KVcuRq8V300NSWnoEGf6cvmsE4BqP1NXaJByx2krhez2MA1Oy7bAm75yZfWB6aBzDC hhTt2T3U6iFMcRW8C0KqLm7viGUqoODEvf7GHSHHB70Y4oBfWnXE21MP0EgUdIP12l zXMikHwRkRM686lIKdSKRHxDwSm3ecQ8kQUCDJ64PrExOI/5gRyhSpZx9AmsODJr59 8hzn2ih++hcfstxAffxw1tsagWoKan4Zd9IgQPztZOtsq1V897DYuz9fXnw14X+Dfn B3o36TDjK/DLw== Date: Thu, 14 Apr 2022 13:02:35 +0100 From: Mark Brown To: Tianjia Zhang Cc: Will Deacon , Catalin Marinas , Jonathan Corbet , Marc Zyngier , Joey Gouly , Vincenzo Frascino , Arnd Bergmann , Anshuman Khandual , Fuad Tabba , Mark Rutland , Vladimir Murzin , James Morse , Suzuki K Poulose , Mathieu Poirier , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64/sme: Add hwcap for Scalable Matrix Extension Message-ID: References: <20220414115544.36204-1-tianjia.zhang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="+rYMHzJdtMjheiS/" Content-Disposition: inline In-Reply-To: <20220414115544.36204-1-tianjia.zhang@linux.alibaba.com> X-Cookie: Available while quantities last. Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --+rYMHzJdtMjheiS/ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Apr 14, 2022 at 07:55:44PM +0800, Tianjia Zhang wrote: > Allow userspace to detect support for SME (Scalable Matrix Extension) > by providing a hwcap for it, using the official feature name FEAT_SME, > declared in ARM DDI 0487H.a specification. There's already a hwcap for the core feature and all the subfeatures added as part of the series I've been posting for SME: https://lore.kernel.org/linux-arm-kernel/20220408114328.1401034-1-broonie@kernel.org/ Why add something independently, especially given that there is no way for userspace to do anything constructive with the feature without the rest of the kernel support? Any attempt to use SME instructions without kernel support will trap and generate a SIGILL even if the feature is present in hardware. Do you have a system with SME that you're trying to use? Review/testing on the current series would be appreciated. --+rYMHzJdtMjheiS/ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmJYDVoACgkQJNaLcl1U h9C6fwf/dCBmg/zhXRJuqkE6TkDJhHFIVir86wHs+dD172jNkEN03cI131CuQrlc rot+y4RI9226F9cCcLAdUmywlicGsMbHujJyKF2C0oG5MoKZ6FuiR4Z3RNymubzE oE7BQZ7iHR3hHZF1mkH9pYkuUm4by/jnGwurrxN5oUpum1p1+CsyWWPuytdMRfBh n3vf+v1Su7WvNZCmwOu7geR+JysQnVTOEzgU9VSnkUU2sDLUaADc1LXEvNGl3Wmr 6i8V27uiy3DmzdNH7PU4J7m/Uv3ANOS4K+mkzS0SOkEa0MmvgxIiJtgDQupe6XsG 9B+81gF30PY0rmuIQe2l3iG91D1BPg== =dqIZ -----END PGP SIGNATURE----- --+rYMHzJdtMjheiS/--