From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9750E19E7DB for ; Thu, 25 Jul 2024 17:46:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721929580; cv=none; b=hdvRtUqZMnD3LY7MtdCIiH9U2VeBPgP48znTl4x8+jiZKQ83wfe3nOayAmXc53B2KAiDQScWgyUIKKhhBy2SCMOaGxQib/qvNSTo4MafPtxlSRPPU8DAALhMVpyZdU9JOK1iaNctALYaYSnpo0m4H3LD6x2iLXDuq/uxxIXSNL4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721929580; c=relaxed/simple; bh=GMwDt/ChBOUZDWsSheWZPzKHXlsm6eS7M3CCDHwPsdk=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=O06wA8vYn/QG/R/UTfuRNQU0fo8NL6ug9IXYyNbqFuMZFZD84jaNgNQ9QsEMHNqtrv4K+4P4rDx/KHeHTeq/nUdkMLpu02zn22MvkR43xkcoP2e3p/0Hj8zq1Y0zMZgW4//m6AcSsBa2hGMv4q2X1vOQA+rhKT91yOT6dkSeXls= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BEh76sq7; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BEh76sq7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1721929577; h=from:from:reply-to:subject:subject: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=tL9pmqSf/aNDfhH/ueAeonuzBcQhvBuggsfkfiNu6zI=; b=BEh76sq7NVpG+7V5DiBanEWEB/+QJ3xk+ZDkoxGxme7EbrVoDp910RP2B0+AbFzxKDE2xu f0LrnMXegqznFKZDGZ11XxV2XN2ASzG4K4YxnG5izx+97hx/TLui8K3lsrls9HAaj3SMue zv2zRNn8O6oKh4IPtWjpbAZosP4fxgY= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-74-s8YB37UjO-KU1XHKZ3vbuw-1; Thu, 25 Jul 2024 13:46:15 -0400 X-MC-Unique: s8YB37UjO-KU1XHKZ3vbuw-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 92BF31955D45; Thu, 25 Jul 2024 17:46:13 +0000 (UTC) Received: from file1-rdu.file-001.prod.rdu2.dc.redhat.com (unknown [10.11.5.21]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 909461955D48; Thu, 25 Jul 2024 17:46:12 +0000 (UTC) Received: by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix, from userid 12668) id 8283430C1C17; Thu, 25 Jul 2024 17:46:11 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix) with ESMTP id 7EF523FD4B; Thu, 25 Jul 2024 19:46:11 +0200 (CEST) Date: Thu, 25 Jul 2024 19:46:11 +0200 (CEST) From: Mikulas Patocka To: James Bottomley cc: John David Anglin , John David Anglin , Helge Deller , linux-parisc@vger.kernel.org Subject: Re: ARCH_DMA_MINALIGN on PA-RISC In-Reply-To: <3b09e01e90d144043934eafed8b9c70da3b754b4.camel@HansenPartnership.com> Message-ID: References: <93fcf9-f61b-7620-b5f1-d44449d280c9@redhat.com> <54cb80b8-9c89-4b61-b1cd-1e626daf6719@bell.net> <3b09e01e90d144043934eafed8b9c70da3b754b4.camel@HansenPartnership.com> Precedence: bulk X-Mailing-List: linux-parisc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="185210117-88892401-1721929571=:461109" X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --185210117-88892401-1721929571=:461109 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Thu, 25 Jul 2024, James Bottomley wrote: > > > #define ARCH_DMA_MINALIGN       (128) > > > #define ARCH_KMALLOC_MINALIGN   (8) > > > > > > L1_CACHE_BYTES is 64 on arm64. > > > > > > Possibly, the same can occur on parisc. > > > > > > Dave > > > > L1_CACHE_BYTES is a performance hint that is used to avoid cache line > > ping-pong when multiple CPUs modify nearby data. > > > > ARCH_DMA_MINALIGN is the biggest possible cache line size to avoid > > DMA data corruption. As there are some arm64 machines with 128-byte > > cache line, arm64 has to define it to 128. > > > > James said that the L2 cache on PA8800/8900 is coherent with PCI. So, > > I think that ARCH_DMA_MINALIGN should be 64 (is that the L1 cache > > line size on PA8800/8900?). > > By default, if unset, ARCH_DMA_MINALIGN defaults to alignof(long long), > so it is already 64 on parisc. > > James No, alignof(long long) is 8 :-) Mikulas --185210117-88892401-1721929571=:461109--