From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4EC682F7F09 for ; Mon, 15 Jun 2026 08:21:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781511676; cv=none; b=UY0OfDkf4jh9JuHwyCOJ5dxSdkYW1sTkKXxM1OKP/jNEr0gfts5tT81fL/vno5j5VdLIm6u7pR7gjFzw20fLe2exbAdnDIF6zRtaXrafovgvYhVCkaTsGnF5STD+Ax8FC6vbRpIQGcV7LyVCcdKyxEs0jIAaRL7/pPJ0hX8qCQM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781511676; c=relaxed/simple; bh=H9RcXIwiWUq0JGOm1ZTKIwPAmScmxjyBR0Kh6TUjioM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=ZuoqesSPMSRvlEfxvFsKIiktfApCdFaM5O2DduVmZkwhKA0+RgKPfdzjU3Jyvq7VpOXwl2ilMAM4Kvaj5bgWsIz0qM3chkxlvY9Xf6pLYNuJqYHeHqHWtDwdUntbyhJhevT2M0y26J3mmv6dBSfivBbhXoDqKIi1jj1hjNYxXV0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de; spf=pass smtp.mailfrom=suse.de; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=00SmjGQe; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=IGSmQ3dH; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=O+0Zf1Ke; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=5uKPv/xx; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="00SmjGQe"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="IGSmQ3dH"; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="O+0Zf1Ke"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="5uKPv/xx" Received: from hawking.suse.de (unknown [10.168.4.11]) by smtp-out2.suse.de (Postfix) with ESMTP id 7C99475B27; Mon, 15 Jun 2026 08:21:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1781511673; 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=00SmjGQekfRMI2a4nPcidhWzQO4m7IPrhZVXXZ0pHvCBq6N+LYKe+xTzr6SqlGjjBSxsKY piMJRE7l+TfaiHmiLnJzWeNmoQ01935RbFgf1Dxiwf89ZGkVNdHrPuG33qPFgDl/rzIpHT t5PLj79/U0jmo9OBm7kkSZvzf0sWzZw= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1781511673; 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=IGSmQ3dHMCSQ8Bt17qqsNwVWBKpei51aqPvK5cvI2gH0E69XOCIL7uqt+waacWYJ+Pwlmo zGOao01C0axraCBA== Authentication-Results: smtp-out2.suse.de; none DKIM-Signature: v=1; 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: linux-kernel@vger.kernel.org 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."