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 7402BC433F5 for ; Mon, 8 Nov 2021 18:45:26 +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 8ADBC61506 for ; Mon, 8 Nov 2021 18:45:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 8ADBC61506 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.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 25F7B838DD; Mon, 8 Nov 2021 19:45:23 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Authentication-Results: phobos.denx.de; dkim=pass (2048-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b="oX/fwgnl"; dkim-atps=neutral Received: by phobos.denx.de (Postfix, from userid 109) id 08D7483886; Mon, 8 Nov 2021 19:45:21 +0100 (CET) Received: from mail-yb1-xb35.google.com (mail-yb1-xb35.google.com [IPv6:2607:f8b0:4864:20::b35]) (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 C752C83886 for ; Mon, 8 Nov 2021 19:45:15 +0100 (CET) Authentication-Results: phobos.denx.de; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=ilias.apalodimas@linaro.org Received: by mail-yb1-xb35.google.com with SMTP id e136so42869665ybc.4 for ; Mon, 08 Nov 2021 10:45:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :content-transfer-encoding; bh=K/xDF2K3AnFXTqgidkDx7ntwDm/b5G2ACCzyXCtGOVI=; b=oX/fwgnlwYEqx+laafE3DA6AtZDuMMIZdu7skyBQgn9dZ7DxuNPMY3Og2vc6W7UVxd NYKa80ruoE7ULgHhgFEYidfpbTJHGQIj2vTzF/dKmfoQFklEhicxkXA+8mT1IkwJnKNu qCwNR6jBkKDDwbhQ6z+K5wdmNi/zb3j1a98qn9ckIOi4KZEJ06QC1r8MLpF5JruU0XoQ aembRBxxAWSR9DCbCNdecioy/e18Ml69jFKbaV/Y/g+VCkqEsu9QfqLedaQTPqNja9gO u5o8mirX+QJEb+u/D2L8ZPG737Ci1F3k6VEYe7VSZb1wVd/PG0oHS4mijnGzEm2uc2cz Z5gg== 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:content-transfer-encoding; bh=K/xDF2K3AnFXTqgidkDx7ntwDm/b5G2ACCzyXCtGOVI=; b=Fr1kHIq8gDHTDU4gByw0pRoQLInc8PhMR9pKdatLTJbYz5mjS4WRAolJ0Eqi6PBjJn 1opVYiMkEPv8o2sr2/IoRNvqBlf/ZUZ/ClyiuECV2sXkYkHm0WrmDPPGmSsnGO1OROaE GN3bXuX1rvwk9a7BwIdG1+RUFFyUp/O3kmCS3vl3AgkYVAvLXzoPdfxbtdHZozak8xS4 wDGRhTLOBRT5XABpCzt341qsJM8hTVaQdxMI/GTgdHdTOJ14ZKstZ2yF3Y7qVdx4407F v9N4GaG+jHuse2hQVJoz1+0/orvStkqPBXLN6gbjQGDhYWRu5w0kBBeoc1H8OCEmAHzP vPwg== X-Gm-Message-State: AOAM532BpsJYyqdYGDCfULNFT9A9Q9vUjJy+rhAq8Rr9hMEeYTSNXl99 w7eA2hTgNjuzIEeQaarqnhIk5Mf97wFqBpOVweR0Rw== X-Google-Smtp-Source: ABdhPJw6rSrnwfkoK4GONsiIJaYrKq8nvG5IXz93wPawFaYKot/WaG2zq0m2ocINqktmGzhy9A0+bOrOtF1zNWGxpIY= X-Received: by 2002:a25:8388:: with SMTP id t8mr1519117ybk.79.1636397110982; Mon, 08 Nov 2021 10:45:10 -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: <20211108044637.GD16401@laputa> From: Ilias Apalodimas Date: Mon, 8 Nov 2021 20:44:34 +0200 Message-ID: Subject: Re: [RFC 07/22] dm: blk: add UCLASS_PARTITION To: AKASHI Takahiro , Simon Glass , Heinrich Schuchardt , Tom Rini , U-Boot Mailing List , Ilias Apalodimas , 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 chiming in a little late but On Mon, 8 Nov 2021 at 06:46, AKASHI Takahiro w= rote: > > 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 Schuchard= t 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 Takahiro= : > > > > > >>>>>>>> On Fri, Oct 29, 2021 at 06:57:24AM +0200, Heinrich Schuc= hardt wrote: > > > > > >>>>>>>>> > > > > > >>>>>>>>> > > > > > >>>>>>>>>> I agree with Heinrich that we are better to leave BLK = as it is, both > > > > > >>>>>>>>>> in name and meaning. I think maybe I am missing the gi= st of your > > > > > >>>>>>>>>> argument. > > > > > >>>>>>>>>> > > > > > >>>>>>>>>> If we use UCLASS_PART, for example, can we have that r= efer to both s/w > > > > > >>>>>>>>>> and h/w partitions, as Herinch seems to allude to belo= w? What would > > > > > >>>>>>>>>> the picture look like the, and would it get us closer = to agreement? > > > > > >>>>>>>>> > > > > > >>>>>>>>> In the driver model: > > > > > >>>>>>>>> > > > > > >>>>>>>>> A UCLASS is a class of drivers that share the same inte= rface. > > > > > >>>>>>>>> A UDEVICE is a logical device that belongs to exactly o= ne UCLASS and is > > > > > >>>>>>>>> accessed through this UCLASS's interface. > > > > > >>>>>>>> > > > > > >>>>>>>> Please be careful about "accessed through" which is a qu= ite confusing > > > > > >>>>>>>> expression. I don't always agree with this view. > > > > > >>>>>>>> > > > > > >>>>>>>>> A hardware partition is an object that exposes only a s= ingle interface > > > > > >>>>>>>>> for block IO. > > > > > >>>>>>>>> > > > > > >>>>>>>>> A software partition is an object that may expose two i= nterfaces: 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 blo= ck devices > > > > > >>>>>>>> on UEFI system should always have a (sw) partition table= or not. > > > > > >>>>>>>> But it is a different topic. > > > > > >>>>>>>> > > > > > >>>>>>>>> The UEFI model does not have a problem with this becaus= e on a handle you > > > > > >>>>>>>>> can install as many different protocols as you wish. Bu= t U-Boot's driver > > > > > >>>>>>>>> model only allows a single interface per device. Up to = now U-Boot has > > > > > >>>>>>>>> overcome this limitation by creating child devices for = the extra interfaces. > > > > > >>>>>>>> > > > > > >>>>>>>>> We have the following logical levels: > > > > > >>>>>>>>> > > > > > >>>>>>>>> Controller | Block device | Software Partition| Fi= le system > > > > > >>>>>>>>> ----------------+--------------+-------------------+---= --------- > > > > > >>>>>>>>> NVMe Drive | Namespace | Partition 1..n | FA= T, 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 app= ear 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 table. > > > > > >>>>>> > > > > > >>>>>> I can have a DOS partition that covers the whole device, w= ithout 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 most= ly independent of the block device type we should use separate uclasses and= udevices. > > > > > >>>>>>> > > > > > >>>>>>>> I also remember that you claimed that not all efi object= s(handles and > > > > > >>>>>>>> protocols like SIMPE_FILE_SYSTEM_PROTOCOL) need to have = corresponding > > > > > >>>>>>>> U-Boot counterparts in our 2019 discussion. > > > > > >>>>>>>> > > > > > >>>>>>>> If we *need* PARTITION_TALBLE, why don't we have HW_PART= ITION_TABLE, > > > > > >>>>>>>> which should support other type of hw partitions as well= ? > > > > > >>>>>>> > > > > > >>>>>>> How hardware partitions, LUNs, ATA drives are enumerated = is specific to the type of controller while the type of software partition = table is independent of the block device. > > > > > >>>>>>> > > > > > >>>>>>>> > > > > > >>>>>>>> |-- eMMC controller (UCLASS_MMC) > > > > > >>>>>>>> | |-- eMMC device1 / Physical media (UCLASS_HW_PARTITION= _TABLE?) > > > > > >>>>>>>> | |-- Block device / HW Partition:user data (UCLASS_BL= K) > > > > > >>>>>>>> | | |-- 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_PARTITION= _TABLE?) > > > > > >>>>>>>> > > > > > >>>>>>>> |-- scsi controller (UCLASS_SCSI) > > > > > >>>>>>>> | |-- scsi disk / Physical media (UCLASS_HW_PARTITION_TA= BLE?) > > > > > >>>>>>>> | |-- 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 mo= re complicated.) > > > > > >>>>>>>> > > > > > >>>>>>>> This kind of complex hierarchy doesn't benefit anybody. > > > > > >>>>>>> > > > > > >>>>>>> All these levels exist already. We simply do not model th= em yet in the DM way. > > > > > >>>>>>> > > > > > >>>>>>> The device tree depth is the outcome of the udevice expos= ing always only a single interface defined by the uclass. > > > > > >>>>>>> > > > > > >>>>>>> The UEFI design allows installing multiple protocol inter= faces on a single handle. This may result in simpler device trees in some c= ases. > > > > > >>>>>> > > > > > >>>>>> Yes, the complexity has to go somewhere. With driver model= 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 partition > > > > > >>>>>> | |-- Block device (UCLASS_BLK) - e.g. for a different= 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 fil= esystem, so could do: > > > > > >>>>>> > > > > > >>>>>> |-- Controller (UCLASS_MMC) > > > > > >>>>>> | |-- Block device (UCLASS_BLK) - 'usual' HW partition= (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 different= 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 necessary= . > > > > > >>>>> > > > > > >>>>> Are further MMC hw partitions, multiple SCSI LUNs and multi= ple NVME namespaces already treated as separate BLK devices? > > > > > >>>> > > > > > >>>> Yes. > > > > > >>>> What I meant to say is that, if we don't need a partition ta= ble 'udevice' > > > > > >>>> for hw partitions, we don't need such a device for sw partit= ions neither. > > > > > >>>> > > > > > >>>> Meanwhile, what about UCLASS_FS? Why do we need this? > > > > > >>> > > > > > >>> We don't need it for our current discussion, but if we want t= o 'open' > > > > > >>> the filesystem and keep the metadata around, rather than read= ing it > > > > > >>> again every time we access a file, we might find it useful. O= pen files > > > > > >>> could be children of the FS uclass, perhaps, if we go a step = further > > > > > >>> and create devices for them. > > > > > >> > > > > > >> Do you want to invent linux-like mount-point concepts or procf= s? > > > > > >> I remember that you didn't want to have child nodes under BLK = 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 wron= g thing > > > > > > somewhere along the way. For example, a partition would be unde= r 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 partitions = (s/w > > > > > > and hw/). As I understand it, that's what we've been discussing= . > > > > > > > > > > The discovery of hardware partitions is specific to the block dev= ice > > > > > 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 hardw= are > > > > > partitions does not seem necessary. > > > > > > > > I can see the reasoning here. It might not stand the test of time b= ut > > > > how about we go with it for now? For MMC hardware partition we woul= d > > > > 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 harbo= ring > > > > > 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. Thanks /Ilias [...]