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 phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 21EFCCAC5A0 for ; Thu, 18 Sep 2025 12:07:37 +0000 (UTC) Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id A0DE083287; Thu, 18 Sep 2025 14:07:35 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=fail (p=reject dis=none) header.from=andestech.com Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Received: by phobos.denx.de (Postfix, from userid 109) id A0A0D83287; Thu, 18 Sep 2025 14:07:34 +0200 (CEST) Received: from Atcsqr.andestech.com (60-248-80-70.hinet-ip.hinet.net [60.248.80.70]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by phobos.denx.de (Postfix) with ESMTPS id 9A75083285 for ; Thu, 18 Sep 2025 14:07:31 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=fail (p=reject dis=none) header.from=andestech.com Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=ycliang@andestech.com Received: from mail.andestech.com (ATCPCS34.andestech.com [10.0.1.134]) by Atcsqr.andestech.com with ESMTPS id 58IC77Th088722 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=OK); Thu, 18 Sep 2025 20:07:07 +0800 (+08) (envelope-from ycliang@andestech.com) Received: from swlinux02 (10.0.15.183) by ATCPCS34.andestech.com (10.0.1.134) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Thu, 18 Sep 2025 20:07:07 +0800 Date: Thu, 18 Sep 2025 20:07:05 +0800 From: Leo Liang To: Yao Zi CC: Rick Chen , Tom Rini , "Chia-Wei, Wang" , Simon Glass , Subject: Re: [PATCH v2 1/3] riscv: Add Kconfig options to distinguish Zaamo and Zalrsc Message-ID: References: <20250902081932.21103-1-ziyao@disroot.org> <20250902081932.21103-2-ziyao@disroot.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250902081932.21103-2-ziyao@disroot.org> User-Agent: Mutt/2.2.10 (e0e92c31) (2023-03-25) X-Originating-IP: [10.0.15.183] X-ClientProxiedBy: ATCPCS33.andestech.com (10.0.1.100) To ATCPCS34.andestech.com (10.0.1.134) X-DKIM-Results: atcpcs34.andestech.com; dkim=none; X-DNSRBL: X-MAIL: Atcsqr.andestech.com 58IC77Th088722 X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.39 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.8 at phobos.denx.de X-Virus-Status: Clean On Tue, Sep 02, 2025 at 08:19:30AM +0000, Yao Zi wrote: > Ratified on Apr. 2024, the original RISC-V "A" extension is now split > into two separate extensions, "Zaamo" for atomic operations and "Zalrsc" > for load-reserved/store-conditional instructions. > > For now, we've already seen real-world designs implement the Zalrsc > extension only[2]. As U-Boot mainly runs with only one HART, we could > easily support these designs by not using AMO instructions in the > hard-written assembly if necessary, for which this patch introduces two > new Kconfig options to indicate the availability of "Zaamo" and "Zalrsc". > > Note that even with this patch, "A" extension is specified in the ISA > string passed to the compiler as long as one of "Zaamo" or "Zalrsc" is > available, since they're only recognized with a quite recent version of > GCC/Clang. The compiler usually doesn't automatically generate atomic > instructions unless the source explicitly instructs it to do so, thus > this should be safe. > > Link: https://github.com/riscv/riscv-zaamo-zalrsc/commit/d94c64c63e9120d56bdeb540caf2e5dae60a8126 # [1] > Link: https://lore.kernel.org/u-boot/20250729162035.209849-9-uros.stajic@htecgroup.com/ # [2] > Signed-off-by: Yao Zi > --- > arch/riscv/Kconfig | 17 +++++++++++++++++ > arch/riscv/Makefile | 7 ++++++- > 2 files changed, 23 insertions(+), 1 deletion(-) Reviewed-by: Leo Yu-Chi Liang