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 617F4C87FD2 for ; Sun, 3 Aug 2025 01:24:35 +0000 (UTC) Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id 9F28483CDF; Sun, 3 Aug 2025 03:24:33 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=fail (p=none dis=none) header.from=gentoo.org 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 EC79983CE3; Sun, 3 Aug 2025 03:24:31 +0200 (CEST) Received: from smtp.gentoo.org (mail.gentoo.org [IPv6:2001:470:ea4a:1:5054:ff:fec7:86e4]) (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 6DAAA83C91 for ; Sun, 3 Aug 2025 03:24:29 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=fail (p=none dis=none) header.from=gentoo.org Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=dlan@gentoo.org Received: from localhost (unknown [116.232.147.33]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange secp256r1 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dlan) by smtp.gentoo.org (Postfix) with ESMTPSA id 8B05833BE32; Sun, 03 Aug 2025 01:24:26 +0000 (UTC) Date: Sun, 3 Aug 2025 09:24:22 +0800 From: Yixun Lan To: Yao Zi Cc: Rick Chen , Leo , Tom Rini , "Chia-Wei, Wang" , Simon Glass , u-boot@lists.denx.de Subject: Re: [PATCH 1/2] riscv: Add Kconfig options to distinguish Zaamo and Zalrsc Message-ID: <20250803012422-GYA937575@gentoo> References: <20250802092155.40915-1-ziyao@disroot.org> <20250802092155.40915-2-ziyao@disroot.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250802092155.40915-2-ziyao@disroot.org> 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 Hi Yao, On 09:21 Sat 02 Aug , 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 ++++++- > configs/ibex-ast2700_defconfig | 3 ++- > 3 files changed, 25 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 8c6feae5735..b1c2d657e99 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -339,10 +339,27 @@ endmenu > > config RISCV_ISA_A > bool "Standard extension for Atomic Instructions" > + depends on RISCV_ISA_ZAAMO && RISCV_ISA_ZALRSC > default y > help > Adds "A" to the ISA string passed to the compiler. > > +config RISCV_ISA_ZAAMO > + bool "Standard extension for Atomic Memory Operations" > + default y > + help > + Indicates the platform supports Zaamo extension for atomic memory > + operations. Assembly routines won't use AMO instructions if set > + to n. > + > +config RISCV_ISA_ZALRSC > + bool "Standard extension for LR/SC instructions" > + default y > + help > + Indicates the platform supports Zalrsc extension for load-reserved > + and store-conditional instructions. Assembly rutines won't use > + LR/SC instructions if set to n. > + > config RISCV_ISA_ZICBOM > bool "Zicbom support" > depends on !SYS_DISABLE_DCACHE_OPS > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > index 6f80f4a7108..fdda6da1df3 100644 > --- a/arch/riscv/Makefile > +++ b/arch/riscv/Makefile > @@ -11,7 +11,12 @@ ifeq ($(CONFIG_ARCH_RV32I),y) > ARCH_BASE = rv32im > ABI_BASE = ilp32 > endif > -ifeq ($(CONFIG_RISCV_ISA_A),y) > +# GCC starts to recognize "Zaamo" and "Zalrsc" from version 15, which is quite > +# recent. We don't bother checking the exact compiler version, but pass "A" > +# extension for -march as long as one of "Zaamo" or "Zalrsc" is available. > +ifeq ($(findstring y,$(CONFIG_RISCV_ISA_A) \ > + $(CONFIG_RISCV_ISA_ZAAMO) \ > + $(CONFIG_RISCV_ISA_ZALRSC)),y) > ARCH_A = a > endif > ifeq ($(CONFIG_RISCV_ISA_F),y) > diff --git a/configs/ibex-ast2700_defconfig b/configs/ibex-ast2700_defconfig > index f088aec8716..eb5cab43645 100644 > --- a/configs/ibex-ast2700_defconfig > +++ b/configs/ibex-ast2700_defconfig > @@ -23,7 +23,8 @@ CONFIG_SYS_MEM_TOP_HIDE=0x10000000 > CONFIG_BUILD_TARGET="" > CONFIG_TARGET_ASPEED_AST2700_IBEX=y > # CONFIG_RISCV_ISA_F is not set > -# CONFIG_RISCV_ISA_A is not set > +# CONFIG_RISCV_ISA_ZAAMO is not set > +# CONFIG_RISCV_ISA_ZALRSC is not set this is confusing, while in this patchset it actually equal to : # CONFIG_RISCV_ISA_ZAAMO is not set CONFIG_RISCV_ISA_ZALRSC=y also I believe changes for configs/ibex-ast2700_defconfig should go as an independent patch, please separate it > # CONFIG_SPL_SMP is not set > CONFIG_XIP=y > CONFIG_SPL_XIP=y > -- > 2.50.1 > -- Yixun Lan (dlan)