From patchwork Tue Nov 29 14:47:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Conor Dooley X-Patchwork-Id: 629269 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 DA960C4167B for ; Tue, 29 Nov 2022 14:51:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234100AbiK2OvV (ORCPT ); Tue, 29 Nov 2022 09:51:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230391AbiK2OvS (ORCPT ); Tue, 29 Nov 2022 09:51:18 -0500 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.153.233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D083BAD; Tue, 29 Nov 2022 06:51:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1669733477; x=1701269477; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=CX12l/BYcHckW0nxt5dW6uGaSf9bcCVSRsIUm2MrbaY=; b=DA7JrLVpepXpqVe7J3e2kwZ+2bgGr0OHLrpTZxiKLMLF79BDOa4stEqY I8B2ZS8uBISd6Z0UqtscpECyUSiJcZAItm+PRAGz7A3DTBy3tf6r4+5ZQ SIxG3jkIfvUBkTTMwlcmtSbM8qqeO66s1Ua5DS2ANj6uuX0TndFDDM49f N8YbB11V68H0m7QlHoOxap31wAWajstPyc+lCepwE7XgJ3/7G2LnRVpyn FSe3tfWz6kaBrc3YHQgGq8SmmK2IqTfFZlHfh1zqnHtxm7S/9qqg9d95W Oacz2NlwhR1DWxiJhHbM5Sqwyeg9D+Hq3ANE0czNXepfLAGNZT053nBqU A==; X-IronPort-AV: E=Sophos;i="5.96,203,1665471600"; d="scan'208";a="190983230" Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa5.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 29 Nov 2022 07:51:17 -0700 Received: from chn-vm-ex03.mchp-main.com (10.10.85.151) by chn-vm-ex01.mchp-main.com (10.10.85.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.12; Tue, 29 Nov 2022 07:51:15 -0700 Received: from wendy.microchip.com (10.10.115.15) by chn-vm-ex03.mchp-main.com (10.10.85.151) with Microsoft SMTP Server id 15.1.2507.12 via Frontend Transport; Tue, 29 Nov 2022 07:51:13 -0700 From: Conor Dooley To: CC: Conor Dooley , , , , , , , , , , , Subject: [RFC 1/2] RISC-V: clarify ISA string ordering rules in cpu.c Date: Tue, 29 Nov 2022 14:47:42 +0000 Message-ID: <20221129144742.2935581-2-conor.dooley@microchip.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org While the list of rules may have been accurate when created, it now lacks some clarity in the face of isa-manual updates. Specifically: - there is no mention here of a distinction between regular 'Z' extensions which are "Additional Standard Extensions" and "Zxm" extensions which are "Standard Machine-Level Extensions" - there is also no explicit mention of where either should be sorted in the list - underscores are only required between two *multi-letter* extensions but the list of rules implies that this is required between a multi-letter extension and any other extension. IOW "rv64imafdzicsr_zifencei" is a valid string Attempt to clean up the list of rules, by adding information on the above & sprinkling in some white space for readability. Signed-off-by: Conor Dooley --- arch/riscv/kernel/cpu.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c index 852ecccd8920..5e42c92a8456 100644 --- a/arch/riscv/kernel/cpu.c +++ b/arch/riscv/kernel/cpu.c @@ -120,20 +120,32 @@ device_initcall(riscv_cpuinfo_init); .uprop = #UPROP, \ .isa_ext_id = EXTID, \ } + /* * Here are the ordering rules of extension naming defined by RISC-V * specification : - * 1. All extensions should be separated from other multi-letter extensions - * by an underscore. + * + * 1. All multi-letter extensions should be separated from other multi-letter + * extensions by an underscore. + * * 2. The first letter following the 'Z' conventionally indicates the most * closely related alphabetical extension category, IMAFDQLCBKJTPVH. - * If multiple 'Z' extensions are named, they should be ordered first - * by category, then alphabetically within a category. + * 'Z' extensions should be sorted after single-letter extensions and before + * any higher-privileged extensions. + * If multiple 'Z' extensions are named, they should be ordered first by + * category, then alphabetically within a category. + * * 3. Standard supervisor-level extensions (starts with 'S') should be * listed after standard unprivileged extensions. If multiple * supervisor-level extensions are listed, they should be ordered * alphabetically. - * 4. Non-standard extensions (starts with 'X') must be listed after all + * + * 4 Standard machine-level extensions (starts with 'Zxm') should be + * listed after any lower-privileged, standard extensions. If multiple + * machine-level extensions are listed, they should be ordered + * alphabetically. + * + * 5. Non-standard extensions (starts with 'X') must be listed after all * standard extensions. They must be separated from other multi-letter * extensions by an underscore. */