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 X-Spam-Level: X-Spam-Status: No, score=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EF90C31E45 for ; Thu, 13 Jun 2019 17:16:35 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2EFE52053B for ; Thu, 13 Jun 2019 17:16:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2EFE52053B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=rowland.harvard.edu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 05A5A12D4; Thu, 13 Jun 2019 17:16:35 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id C92AB119E for ; Thu, 13 Jun 2019 17:16:33 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from iolanthe.rowland.org (iolanthe.rowland.org [192.131.102.54]) by smtp1.linuxfoundation.org (Postfix) with SMTP id 39F1E82F for ; Thu, 13 Jun 2019 17:16:33 +0000 (UTC) Received: (qmail 4216 invoked by uid 2102); 13 Jun 2019 13:16:32 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 13 Jun 2019 13:16:32 -0400 Date: Thu, 13 Jun 2019 13:16:32 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Christoph Hellwig , Valentina Manea , Shuah Khan Subject: Re: How to resolve an issue in swiotlb environment? In-Reply-To: <20190613073900.GC12093@lst.de> Message-ID: MIME-Version: 1.0 Cc: Linux-Renesas , "linux-usb@vger.kernel.org" , Oliver Neukum , "linux-block@vger.kernel.org" , "iommu@lists.linux-foundation.org" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Thu, 13 Jun 2019, Christoph Hellwig wrote: > On Wed, Jun 12, 2019 at 10:43:11AM -0400, Alan Stern wrote: > > Would it be okay to rely on the assumption that USB block devices never > > have block size < 512? (We could even add code to the driver to > > enforce this, although refusing to handle such devices at all might be > > worse than getting an occasional error.) > > sd.c only supports a few specific sector size, and none of them is > < 512 bytes: > > if (sector_size != 512 && > sector_size != 1024 && > sector_size != 2048 && > sector_size != 4096) { > ... > sdkp->capacity = 0; Great! So all we have to do is fix vhci-hcd. Then we can remove all the virt_boundary_mask stuff from usb-storage and uas entirely. (I'm assuming wireless USB isn't a genuine issue. As far as I know, it is pretty much abandoned at this point.) Valentina and Shua: Adding SG support to vhci-hcd shouldn't be too hard. It ought to be possible even without changing the network protocol. Alan Stern _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu