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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4F8EC433EF for ; Tue, 9 Nov 2021 00:09:27 +0000 (UTC) Received: from phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DA941610E8 for ; Tue, 9 Nov 2021 00:09:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DA941610E8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.denx.de Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id 5359283653; Tue, 9 Nov 2021 01:09:24 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Authentication-Results: phobos.denx.de; dkim=pass (1024-bit key; unprotected) header.d=chromium.org header.i=@chromium.org header.b="le5ukrJt"; dkim-atps=neutral Received: by phobos.denx.de (Postfix, from userid 109) id 9451083830; Tue, 9 Nov 2021 01:09:22 +0100 (CET) Received: from mail-ua1-x936.google.com (mail-ua1-x936.google.com [IPv6:2607:f8b0:4864:20::936]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits)) (No client certificate requested) by phobos.denx.de (Postfix) with ESMTPS id 8F1838364F for ; Tue, 9 Nov 2021 01:09:17 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=sjg@google.com Received: by mail-ua1-x936.google.com with SMTP id t13so19725893uad.9 for ; Mon, 08 Nov 2021 16:09:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=FGxmWLImEPNcWgCMjUhCo8aYR9bKJOolcaUttU3Ucxc=; b=le5ukrJtZMbP/nO7jcXSmjK3O/EfP840Qlhx3xNUf51cNDsbIgZNB9XVduEgkbSI7P 6v/GyaWXCZ0oeqrKbSH5p2J6K8dFukQMicKSuNB7sZJs3R5fcDNiR716v7TGszfWt1SM w/yS58Il5njCI1wsXipYrThaqK4jpvi+mU0b4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=FGxmWLImEPNcWgCMjUhCo8aYR9bKJOolcaUttU3Ucxc=; b=Y9Ajhdh9m9MYWnXmWWbrPVyQR3I9sYSII8uEzfr9JhFJHJbwckrHt1z3FTKtUWX3Gz RHQb/dkKC6UxNh9/wx1xESAMBEwywMtcg0RfhnByuRgqgcFwRusCDIMa/GKSRehB6UB1 1YiIJjQ0/nqNExvFKFDZSRFTOCtw38T7JzZiBci9JSib1e35qudhQgH2yEkXfH7nPhjS 63eV9bqyNghxTNjV69x92OCPydshh2ADkGOLhkUANV/pqXJ7xATzQNExHxhh+hIHkbAd W4Oku6NCF0Kfw3CtYqpjVzabc/opX8Fb9UtHfabcT5XLlWBVgHMjW8R9erzivjWd5yAv e/dA== X-Gm-Message-State: AOAM531J9gshPTUIpK6w5FIarXj9cJhS1wLUvsLajgSo6qka+BhRqV3D dhBTwLnOyajI2pELadlP5EaLpqpiprPktgQkOsiXvg== X-Google-Smtp-Source: ABdhPJzV/R2LZxj/GhcSHFbWLqfvYZNthSiGJvC5E7OM92ZLRmXPhOFOQkXH7Eo/teKhBR3JOb92b62U0REeBR/8cXk= X-Received: by 2002:a05:6102:21a3:: with SMTP id i3mr4779148vsb.8.1636416555790; Mon, 08 Nov 2021 16:09:15 -0800 (PST) MIME-Version: 1.0 References: <20211101003600.GB25300@laputa> <20211101015155.GC25300@laputa> <3b96557b-ff89-19e0-e250-200dc19eb93d@gmx.de> <20211105024929.GD27316@laputa> <20211108044637.GD16401@laputa> In-Reply-To: From: Simon Glass Date: Mon, 8 Nov 2021 17:09:04 -0700 Message-ID: Subject: Re: [RFC 07/22] dm: blk: add UCLASS_PARTITION To: Ilias Apalodimas Cc: AKASHI Takahiro , Heinrich Schuchardt , Tom Rini , U-Boot Mailing List , Alex Graf Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.34 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.2 at phobos.denx.de X-Virus-Status: Clean Hi, On Mon, 8 Nov 2021 at 11:45, Ilias Apalodimas wrote: > > Hi chiming in a little late but > > On Mon, 8 Nov 2021 at 06:46, AKASHI Takahiro = wrote: > > > > On Fri, Nov 05, 2021 at 10:12:16AM -0600, Simon Glass wrote: > > > Hi Takahiro, > > > > > > On Thu, 4 Nov 2021 at 20:49, AKASHI Takahiro wrote: > > > > > > > > On Thu, Nov 04, 2021 at 08:02:05PM -0600, Simon Glass wrote: > > > > > Hi, > > > > > > > > > > On Tue, 2 Nov 2021 at 01:43, Heinrich Schuchardt wrote: > > > > > > > > > > > > > > > > > > > > > > > > On 11/1/21 03:14, Simon Glass wrote: > > > > > > > Hi Takahiro, > > > > > > > > > > > > > > On Sun, 31 Oct 2021 at 19:52, AKASHI Takahiro > > > > > > > wrote: > > > > > > >> > > > > > > >> On Sun, Oct 31, 2021 at 07:15:17PM -0600, Simon Glass wrote: > > > > > > >>> Hi Takahiro, > > > > > > >>> > > > > > > >>> On Sun, 31 Oct 2021 at 18:36, AKASHI Takahiro > > > > > > >>> wrote: > > > > > > >>>> > > > > > > >>>> On Sat, Oct 30, 2021 at 07:45:14AM +0200, Heinrich Schucha= rdt wrote: > > > > > > >>>>> > > > > > > >>>>> > > > > > > >>>>> Am 29. Oktober 2021 23:17:56 MESZ schrieb Simon Glass : > > > > > > >>>>>> Hi, > > > > > > >>>>>> > > > > > > >>>>>> On Fri, 29 Oct 2021 at 13:26, Heinrich Schuchardt wrote: > > > > > > >>>>>>> > > > > > > >>>>>>> > > > > > > >>>>>>> > > > > > > >>>>>>> Am 29. Oktober 2021 08:15:56 MESZ schrieb AKASHI Takahi= ro : > > > > > > >>>>>>>> On Fri, Oct 29, 2021 at 06:57:24AM +0200, Heinrich Sch= uchardt wrote: > > > > > > >>>>>>>>> > > > > > > >>>>>>>>> > > > > > > >>>>>>>>>> I agree with Heinrich that we are better to leave BL= K as it is, both > > > > > > >>>>>>>>>> in name and meaning. I think maybe I am missing the = gist of your > > > > > > >>>>>>>>>> argument. > > > > > > >>>>>>>>>> > > > > > > >>>>>>>>>> If we use UCLASS_PART, for example, can we have that= refer to both s/w > > > > > > >>>>>>>>>> and h/w partitions, as Herinch seems to allude to be= low? What would > > > > > > >>>>>>>>>> the picture look like the, and would it get us close= r to agreement? > > > > > > >>>>>>>>> > > > > > > >>>>>>>>> In the driver model: > > > > > > >>>>>>>>> > > > > > > >>>>>>>>> A UCLASS is a class of drivers that share the same in= terface. > > > > > > >>>>>>>>> A UDEVICE is a logical device that belongs to exactly= one UCLASS and is > > > > > > >>>>>>>>> accessed through this UCLASS's interface. > > > > > > >>>>>>>> > > > > > > >>>>>>>> Please be careful about "accessed through" which is a = quite confusing > > > > > > >>>>>>>> expression. I don't always agree with this view. > > > > > > >>>>>>>> > > > > > > >>>>>>>>> A hardware partition is an object that exposes only a= single interface > > > > > > >>>>>>>>> for block IO. > > > > > > >>>>>>>>> > > > > > > >>>>>>>>> A software partition is an object that may expose two= interfaces: one > > > > > > >>>>>>>>> for block IO, the other for file IO. > > > > > > >>>>>>>> > > > > > > >>>>>>>> Are you talking about UEFI world or U-Boot? > > > > > > >>>>>>>> Definitely, a hw partitions can provide a file system > > > > > > >>>>>>>> if you want. > > > > > > >>>>>>>> It's a matter of usage. > > > > > > >>>>>>>> > > > > > > >>>>>>>> I remember that we had some discussion about whether b= lock devices > > > > > > >>>>>>>> on UEFI system should always have a (sw) partition tab= le or not. > > > > > > >>>>>>>> But it is a different topic. > > > > > > >>>>>>>> > > > > > > >>>>>>>>> The UEFI model does not have a problem with this beca= use on a handle you > > > > > > >>>>>>>>> can install as many different protocols as you wish. = But U-Boot's driver > > > > > > >>>>>>>>> model only allows a single interface per device. Up t= o now U-Boot has > > > > > > >>>>>>>>> overcome this limitation by creating child devices fo= r the extra interfaces. > > > > > > >>>>>>>> > > > > > > >>>>>>>>> We have the following logical levels: > > > > > > >>>>>>>>> > > > > > > >>>>>>>>> Controller | Block device | Software Partition| = File system > > > > > > >>>>>>>>> ----------------+--------------+-------------------+-= ----------- > > > > > > >>>>>>>>> NVMe Drive | Namespace | Partition 1..n | = FAT, EXT4 > > > > > > >>>>>>>>> ATA Controller | ATA-Drive | | > > > > > > >>>>>>>>> SCSI Controller | LUN | | > > > > > > >>>>>>>>> MMC Controller | HW-Partition | | > > > > > > >>>>>>>>> MMC Controller | SD-Card | | > > > > > > >>>>>>>>> USB-Node | USB-Drive | | > > > > > > >>>>>>>>> > > > > > > >>>>>>>>> In the device tree this could be modeled as: > > > > > > >>>>>>>>> > > > > > > >>>>>>>>> |-- Controller (UCLASS_CTRL) > > > > > > >>>>>>>>> | |-- Block device / HW Partition (UCLASS_BLK) (A) > > > > > > >>>>>>>>> | | |-- Partition table (UCLASS_PARTITION_TABLE) (B) > > > > > > >>>>>>>>> | | |-- Software Partition (UCLASS_BLK) > > > > > > >>>>>>>>> | | |-- File system (UCLASS_FS) > > > > > > >>>>>>>>> | | > > > > > > >>>>>>>>> | |-- Block device (UCLASS_BLK) > > > > > > >>>>>>>>> | |-- File system (UCLASS_FS) > > > > > > >>>>>>>> > > > > > > >>>>>>>> I don't know why we expect PARTITION_TABLE and FS to a= ppear in DM tree. > > > > > > >>>>>>>> What is the benefit? > > > > > > >>>>>>>> (A) and (B) always have 1:1 relationship. > > > > > > >>>>>>> > > > > > > >>>>>>> No. You can have a bare device without a partition tabl= e. > > > > > > >>>>>> > > > > > > >>>>>> I can have a DOS partition that covers the whole device,= without a > > > > > > >>>>>> partition table. This is supported in U-Boot and Linux. > > > > > > >>>>>> > > > > > > >>>>>>> > > > > > > >>>>>>> We have several partition table drivers: DOS, GPT, OSX,= ... . In future we should also have one for the NOR Flash partitions. All = of these drivers have a common interface. As the partition table type is mo= stly independent of the block device type we should use separate uclasses a= nd udevices. > > > > > > >>>>>>> > > > > > > >>>>>>>> I also remember that you claimed that not all efi obje= cts(handles and > > > > > > >>>>>>>> protocols like SIMPE_FILE_SYSTEM_PROTOCOL) need to hav= e corresponding > > > > > > >>>>>>>> U-Boot counterparts in our 2019 discussion. > > > > > > >>>>>>>> > > > > > > >>>>>>>> If we *need* PARTITION_TALBLE, why don't we have HW_PA= RTITION_TABLE, > > > > > > >>>>>>>> which should support other type of hw partitions as we= ll? > > > > > > >>>>>>> > > > > > > >>>>>>> How hardware partitions, LUNs, ATA drives are enumerate= d is specific to the type of controller while the type of software partitio= n table is independent of the block device. > > > > > > >>>>>>> > > > > > > >>>>>>>> > > > > > > >>>>>>>> |-- eMMC controller (UCLASS_MMC) > > > > > > >>>>>>>> | |-- eMMC device1 / Physical media (UCLASS_HW_PARTITI= ON_TABLE?) > > > > > > >>>>>>>> | |-- Block device / HW Partition:user data (UCLASS_= BLK) > > > > > > >>>>>>>> | | |-- Partition table (UCLASS_PARTITION_TABLE) > > > > > > >>>>>>>> | | |-- Software Partition (UCLASS_BLK) > > > > > > >>>>>>>> | | |-- File system (UCLASS_FS) > > > > > > >>>>>>>> | | > > > > > > >>>>>>>> | |-- Block device / HW Partition:boot0 (UCLASS_BLK) > > > > > > >>>>>>>> | |-- Block device / HW Partition:boot1 (UCLASS_BLK) > > > > > > >>>>>>>> ... > > > > > > >>>>>>>> | |-- eMMC device2 / Physical media (UCLASS_HW_PARTITI= ON_TABLE?) > > > > > > >>>>>>>> > > > > > > >>>>>>>> |-- scsi controller (UCLASS_SCSI) > > > > > > >>>>>>>> | |-- scsi disk / Physical media (UCLASS_HW_PARTITION_= TABLE?) > > > > > > >>>>>>>> | |-- scsi LUN1 (UCLASS_HW_PARTITION_TABLE?) > > > > > > >>>>>>>> | | |-- Partition table (UCLASS_PARTITION_TABLE) > > > > > > >>>>>>>> | | |-- Software Partition (UCLASS_BLK) > > > > > > >>>>>>>> | |-- scsi LUN2 (UCLASS_HW_PARTITION_TABLE?) > > > > > > >>>>>>>> ... > > > > > > >>>>>>>> > > > > > > >>>>>>>> (Here I ignored scsi buses/channels which make things = more complicated.) > > > > > > >>>>>>>> > > > > > > >>>>>>>> This kind of complex hierarchy doesn't benefit anybody= . > > > > > > >>>>>>> > > > > > > >>>>>>> All these levels exist already. We simply do not model = them yet in the DM way. > > > > > > >>>>>>> > > > > > > >>>>>>> The device tree depth is the outcome of the udevice exp= osing always only a single interface defined by the uclass. > > > > > > >>>>>>> > > > > > > >>>>>>> The UEFI design allows installing multiple protocol int= erfaces on a single handle. This may result in simpler device trees in some= cases. > > > > > > >>>>>> > > > > > > >>>>>> Yes, the complexity has to go somewhere. With driver mod= el I chose to > > > > > > >>>>>> have a single interface per uclass, since it is simpler = to understand, > > > > > > >>>>>> no need to request a protocol for a device, etc. > > > > > > >>>>>> > > > > > > >>>>>> Our current setup is similar to this > > > > > > >>>>>> > > > > > > >>>>>> |-- Controller (UCLASS_MMC) > > > > > > >>>>>> | |-- Block device (UCLASS_BLK) - 'usual' HW partiti= on > > > > > > >>>>>> | |-- Block device (UCLASS_BLK) - e.g. for a differe= nt HW partition* > > > > > > >>>>>> > > > > > > >>>>>> * although I don't think the MMC code actually supports = it - SCSI does though > > > > > > >>>>>> > > > > > > >>>>>> We want to add devices for the partition table and the f= ilesystem, so could do: > > > > > > >>>>>> > > > > > > >>>>>> |-- Controller (UCLASS_MMC) > > > > > > >>>>>> | |-- Block device (UCLASS_BLK) - 'usual' HW partiti= on (the whole device) > > > > > > >>>>>> | | |-- Partition table (UCLASS_PART) - DOS partition (= or EFI) > > > > > > >>>>>> | | | |-- Block device (UCLASS_BLK) - partition 1 > > > > > > >>>>>> | | | | |-- Filesystem (UCLASS_FS) - DOS filesystem > > > > > > >>>>>> | | | |-- Block device (UCLASS_BLK) - partition 2 > > > > > > >>>>>> | | | | |-- Filesystem (UCLASS_FS) - ext5 filesystem > > > > > > >>>>>> | |-- Block device (UCLASS_BLK) - e.g. for a differe= nt HW > > > > > > >>>>>> partition (the whole device) > > > > > > >>>>>> > > > > > > >>>>>> This is similar to Heinrich's, but without the top-level > > > > > > >>>>>> UCLASS_HW_PARTITION_TABLE which I am not sure is necessa= ry. > > > > > > >>>>> > > > > > > >>>>> Are further MMC hw partitions, multiple SCSI LUNs and mul= tiple NVME namespaces already treated as separate BLK devices? > > > > > > >>>> > > > > > > >>>> Yes. > > > > > > >>>> What I meant to say is that, if we don't need a partition = table 'udevice' > > > > > > >>>> for hw partitions, we don't need such a device for sw part= itions neither. > > > > > > >>>> > > > > > > >>>> Meanwhile, what about UCLASS_FS? Why do we need this? > > > > > > >>> > > > > > > >>> We don't need it for our current discussion, but if we want= to 'open' > > > > > > >>> the filesystem and keep the metadata around, rather than re= ading it > > > > > > >>> again every time we access a file, we might find it useful.= Open files > > > > > > >>> could be children of the FS uclass, perhaps, if we go a ste= p further > > > > > > >>> and create devices for them. > > > > > > >> > > > > > > >> Do you want to invent linux-like mount-point concepts or pro= cfs? > > > > > > >> I remember that you didn't want to have child nodes under BL= K devices. > > > > > > >> I'm getting confused about our goal. > > > > > > > > > > > > > > I think we are all a bit unsure. > > > > > > > > > > > > > > I think BLK devices can have children, sorry if I said the wr= ong thing > > > > > > > somewhere along the way. For example, a partition would be un= der a BLK > > > > > > > device, or a FS. > > > > > > > > > > > > > >> What should DM represent in U-Boot world? > > > > > > > > > > > > > > That is what we are trying to figure out. > > > > > > > > > > > > > > I think the minimum is to have a a way to represent partition= s (s/w > > > > > > > and hw/). As I understand it, that's what we've been discussi= ng. > > > > > > > > > > > > The discovery of hardware partitions is specific to the block d= evice > > > > > > controller SCSI/MMC/ATA/NVMe. We currently do not provide any > > > > > > manipulation commands to create hardware partitions (e.g. NVMe > > > > > > namespaces, SCSI LUNs). This is why extracting a uclass for har= dware > > > > > > partitions does not seem necessary. > > > > > > > > > > I can see the reasoning here. It might not stand the test of time= but > > > > > how about we go with it for now? For MMC hardware partition we wo= uld > > > > > just end up with multiple BLK devices, like we do with SCSI LUNs = at > > > > > present, which seems like it should work (with some code tweaks). > > > > > > > > > > > > > > > > > Software partitioning (MBR, GPT, ...) is independent of the har= boring > > > > > > block device. > > > > > > > > > > > > We already have a set of drivers for software partition tables = in disk/. > > > > > > Currently the available methods of the drivers are defined in > > > > > > U_BOOT_PART_TYPE referring to struct part_driver. > > > > > > > > > > > > Currently struct part_driver knows only the following methods: > > > > > > > > > > > > - get_info() > > > > > > - print() > > > > > > - test() > > > > > > > > > > > > These drivers should be ome a uclass. > > > > > > > > > > > > gpt.c and mbr.c allow to create and delete partitions. I think = we should add > > > > > > > > > > > > - create_partition() > > > > > > - delete_partition() > > > > > > > > > > > > to the uclass methods. > > > > > > > > > > That sounds good to me, although since it is a partition uclass, = we > > > > > can just use create() and delete(). > > > > > > > > I don't know why we need a "partition table" device in the middle > > > > of DM hierarchy. > > > > I believe that it simply makes the view of DM tree complicated > > > > without any explicit benefit. > > > > > > Well we clearly have an API here. The partition uclass can: > > > > > > - hold the partition table in dev_get_uclass_priv() > > > - support a read() operation to read the partition > > > - support create() to rewrite the partition table > > > - support delete() to overwrite/erase the partition table > > > > > > Then it means that filesystems have the partition table as a parent > > > (unless they are whole-device filesystems), which makes sense > > > > > > So that's why I like the idea. > > > > > > Other than the extra complexity, is there anything else wrong with it= ? > > > > - First of all, a partition table doesn't look like a 'device' at all. > > - Second, a partition table is just static data for block devices. > > IMO, even if we want to have this data, we can simply hold it > > as some sort of attribute of the device, or maybe as a 'tag' which > > I will introduce in the next version. > > > > -Takahiro Akashi > > > > I don't know how this affect the code, but I agree with Akashi-san > here. It's indeed useful to keep the partition table stored > somewhere, but I think not showing them as part of the device tree is > more intuitive. Well I think I'm easy either way. I just thought that Heinrich made a good case for having a partition uclass. But as Takahiro says, we can use a tag to attach the partition table to the device. But it should be attached to the device's children (the BLK device) not the media device itself, right? Regards, Simon