From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 9BA331411E4; Thu, 18 Apr 2024 14:28:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713450534; cv=none; b=aughiVwx1mu72oPn4tLiYLxMZ0+a9bdNfIgKdW7jwsVIfBNlc3VN+VFSV0oiBItaxM8jIS8o48pXE4YNLFDOJCU++U9fIkRpbgyA+6VuxwqwcRdHvajVozfYjPfjmqV9mD2aE43gLwFz9+jzrD0R60+Wnu3IlSFUtNpMgAKC5+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713450534; c=relaxed/simple; bh=g9aW0yKi9LhdVrspFApEnJlHcPlnA4Sbkv91eE43FPA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dhcXiaNPGs2QcK45mgJc6571woVjFh+c6NKrQ2rPm08dJFq1HIJhRKumsvXC+ow8Cq6SFN+c4UalNpPhGW/UkERuzxIsYAq9JoyrYI1JDrKILC1K/LJpBQwNhJZ/SqCrJJiTdKpKI0Avq7toJC0ytCp9VF16Wv9oWYcPHp/WRnE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=ewajqedC; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ewajqedC" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=KiB0o+jVhF1CLQhKFyf/81T8bBmdPfULP1ceIgm0uGE=; b=ewajqedCwqccTk//ZCZ6mL8nMd Ypd11wlsChKGQ6szQ8gHTJ0hi6c4n6JPgyP9F/b35SQaHEyfMw/dc5NfXBAhHQ1YsEwKgWfbvG4sa lL7etxyLAcdBPK1A+0mxS+ofBQWL/UrfOfwPcFREmtBtGlrTLHfdRSwIL+jT1bEaFhEi3jWRKnSwy LIKFW2BO28AXFiStWq8EGEv5PewRFbdE+HfWYfI3XPy/yrA0eyZE64eiX1ex/JjtQeyI6an3FeMlo Q+9JoqvmHYO0dxEw3c4Oqnp9SfQzRpiwpT5Gfk/a7/W17VP2XUjjgTq9kWBmDHpA2KBK+nYSu1pfM vKbjMW+g==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rxSki-00000005W7K-0uVU; Thu, 18 Apr 2024 14:28:40 +0000 Date: Thu, 18 Apr 2024 15:28:40 +0100 From: Matthew Wilcox To: mhklinux@outlook.com Cc: robin.murphy@arm.com, joro@8bytes.org, will@kernel.org, hch@lst.de, m.szyprowski@samsung.com, corbet@lwn.net, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, petr@tesarici.cz, roberto.sassu@huaweicloud.com Subject: Re: [PATCH 1/1] Documentation/core-api: Add swiotlb documentation Message-ID: References: <20240418135213.426671-1-mhklinux@outlook.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240418135213.426671-1-mhklinux@outlook.com> On Thu, Apr 18, 2024 at 06:52:13AM -0700, mhkelley58@gmail.com wrote: > There's currently no documentation for the swiotlb. Add documentation > describing usage scenarios, the key APIs, and implementation details. > Group the new documentation with other DMA-related documentation. This is really well written. Thank you. One minor nit below. > +Usage Scenarios > +--------------- > +The swiotlb was originally created to handle DMA for devices > +with addressing limitations. As physical memory sizes grew > +beyond 4 Gbytes, some devices could only provide 32-bit DMA > +addresses. By allocating bounce buffer memory below the 4 Gbyte I'd prefer GiB to Gbytes; we might also prefer GB, Gigabyte or Gibibyte, but Gbytes seems wrong. You've written a lot here, and I'm not an expert on swiommu, but nothing else leapt out at me.