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a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1781511672; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rEMFmt8TpTChnVBW1oINDFeDbvwK5qg/ts+tVGLgFE4=; b=O+0Zf1Kede23tZObEsMJ500IJAklAJhZ+rH6jDgDQ4dByMfbiL+1pzWP+jhl5Jku6rSNct 9FCDpgX/Ke/Q7KDHXQ1aD4L+BjHTC76BOzI6nXd7vXQyBfVcXvka7uuApKclSKfaw9RZ44 tjjo9EssNNiP+RJ10KsRg6z6VpVOe8E= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1781511672; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rEMFmt8TpTChnVBW1oINDFeDbvwK5qg/ts+tVGLgFE4=; b=5uKPv/xxuYQO7zwWyAaQ6rr3x7B1IywxUSWbY2LfgbvIx9vVzIzJMmYGh7Swr7O/3sIpOv Np6H4wb7ewmD24Cw== Received: by hawking.suse.de (Postfix, from userid 17005) id 6B1124A056F; Mon, 15 Jun 2026 10:21:12 +0200 (CEST) From: Andreas Schwab To: Zhanpeng Zhang Cc: Tomasz Jeznach , Joerg Roedel , Will Deacon , Robin Murphy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , iommu@lists.linux.dev, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Xu Lu , cuiyunhui@bytedance.com, yuanzhu@bytedance.com Subject: Re: [PATCH v1] iommu/riscv: Support 32-bit register accesses In-Reply-To: <20260615064855.90316-1-zhangzhanpeng.jasper@bytedance.com> (Zhanpeng Zhang's message of "Mon, 15 Jun 2026 14:48:55 +0800") References: <20260615064855.90316-1-zhangzhanpeng.jasper@bytedance.com> Date: Mon, 15 Jun 2026 10:21:12 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Flag: NO X-Spamd-Result: default: False [-4.18 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.18)[-0.910]; MIME_GOOD(-0.10)[text/plain]; RCVD_NO_TLS_LAST(0.10)[]; RCPT_COUNT_TWELVE(0.00)[15]; RCVD_COUNT_ONE(0.00)[1]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; R_RATELIMIT(0.00)[from(RLajr16mudzow8bnf6sy)]; FROM_HAS_DN(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:mid,hawking.suse.de:helo] X-Spam-Level: X-Spam-Score: -4.18 On Jun 15 2026, Zhanpeng Zhang wrote: > +config RISCV_IOMMU_32BIT_ACCESS > + bool "Use 32-bit accesses for RISC-V IOMMU registers" > + depends on RISCV_IOMMU > + help > + Say Y when the RISC-V IOMMU MMIO window cannot be accessed > + using naturally aligned 64-bit loads and stores. > + > + When enabled, 64-bit IOMMU registers are accessed as paired > + 32-bit MMIO operations. This option does not describe an RV32 > + kernel or a 32-bit IOMMU architecture. What is the expected setting in a generic kernel? -- Andreas Schwab, SUSE Labs, schwab@suse.de GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different." 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F178DCD98DE for ; Mon, 15 Jun 2026 08:21:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:References :In-Reply-To:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=BdDGQYV3YPg2beVR07hbc8ReJWR2FBkh6h5e1J5ox6w=; b=W3pv+5wGQtKywt JIfG1gyX3imYNBCpB24Ky0VepXVuos5mJFrSXLbZJoeHDvoaQYE2dWqBF+2bfXhKHyt9yBKvqNbaz jm3/Uo0k+aGU4K3HrAdG4GJG9K0nIGeATZbIzfuFl9g+hGsJwvp0v6JZ6ciwVSfq1jDDf3zJLrnHo 57Q9Tj4tOD4dfQwsEcSaeOxW1nMKcQ1g+dQE6GQigZlKnsdRBb7/ulzG0+1uy0qxVG7Mq6Rg0wTm4 RX7VaOBM80313HIWWMVH1Cv8y/H6dp6muNI8965jSWVHUFj2JwxSLaFZKrmNHSLxwElwWWoB48xf9 LPlsxKkj6Y6aieiGvhfQ==; 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t=1781511672; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rEMFmt8TpTChnVBW1oINDFeDbvwK5qg/ts+tVGLgFE4=; b=5uKPv/xxuYQO7zwWyAaQ6rr3x7B1IywxUSWbY2LfgbvIx9vVzIzJMmYGh7Swr7O/3sIpOv Np6H4wb7ewmD24Cw== Received: by hawking.suse.de (Postfix, from userid 17005) id 6B1124A056F; Mon, 15 Jun 2026 10:21:12 +0200 (CEST) From: Andreas Schwab To: Zhanpeng Zhang Cc: Tomasz Jeznach , Joerg Roedel , Will Deacon , Robin Murphy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , iommu@lists.linux.dev, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Xu Lu , cuiyunhui@bytedance.com, yuanzhu@bytedance.com Subject: Re: [PATCH v1] iommu/riscv: Support 32-bit register accesses In-Reply-To: <20260615064855.90316-1-zhangzhanpeng.jasper@bytedance.com> (Zhanpeng Zhang's message of "Mon, 15 Jun 2026 14:48:55 +0800") References: <20260615064855.90316-1-zhangzhanpeng.jasper@bytedance.com> Date: Mon, 15 Jun 2026 10:21:12 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 X-Spamd-Result: default: False [-4.18 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.18)[-0.910]; MIME_GOOD(-0.10)[text/plain]; RCVD_NO_TLS_LAST(0.10)[]; RCPT_COUNT_TWELVE(0.00)[15]; RCVD_COUNT_ONE(0.00)[1]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; R_RATELIMIT(0.00)[from(RLajr16mudzow8bnf6sy)]; FROM_HAS_DN(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:mid,hawking.suse.de:helo] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260615_012118_061467_D4490B3D X-CRM114-Status: UNSURE ( 7.65 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Jun 15 2026, Zhanpeng Zhang wrote: > +config RISCV_IOMMU_32BIT_ACCESS > + bool "Use 32-bit accesses for RISC-V IOMMU registers" > + depends on RISCV_IOMMU > + help > + Say Y when the RISC-V IOMMU MMIO window cannot be accessed > + using naturally aligned 64-bit loads and stores. > + > + When enabled, 64-bit IOMMU registers are accessed as paired > + 32-bit MMIO operations. This option does not describe an RV32 > + kernel or a 32-bit IOMMU architecture. What is the expected setting in a generic kernel? -- Andreas Schwab, SUSE Labs, schwab@suse.de GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different." _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv