Hi Simon, On Sat, Nov 13, 2021 at 02:32:20PM -0700, Simon Glass wrote: > Hi Heinrich, > > On Sat, 13 Nov 2021 at 11:42, Heinrich Schuchardt <xypron.g...@gmx.de> wrote: > > > > Am 13. November 2021 19:14:32 MEZ schrieb Simon Glass <s...@chromium.org>: > > >Hi, > > > > > >On Mon, 8 Nov 2021 at 17:09, Simon Glass <s...@chromium.org> wrote: > > >> > > >> Hi, > > >> > > >> On Mon, 8 Nov 2021 at 11:45, Ilias Apalodimas > > >> <ilias.apalodi...@linaro.org> wrote: > > >> > > > >> > Hi chiming in a little late but > > >> > > > >> > On Mon, 8 Nov 2021 at 06:46, AKASHI Takahiro > > >> > <takahiro.aka...@linaro.org> 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 > > >> > > > <takahiro.aka...@linaro.org> 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 > > >> > > > > > <xypron.g...@gmx.de> wrote: > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > On 11/1/21 03:14, Simon Glass wrote: > > >> > > > > > > > Hi Takahiro, > > >> > > > > > > > > > >> > > > > > > > On Sun, 31 Oct 2021 at 19:52, AKASHI Takahiro > > >> > > > > > > > <takahiro.aka...@linaro.org> 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 > > >> > > > > > > >>> <takahiro.aka...@linaro.org> wrote: > > >> > > > > > > >>>> > > >> > > > > > > >>>> On Sat, Oct 30, 2021 at 07:45:14AM +0200, Heinrich > > >> > > > > > > >>>> Schuchardt wrote: > > >> > > > > > > >>>>> > > >> > > > > > > >>>>> > > >> > > > > > > >>>>> Am 29. Oktober 2021 23:17:56 MESZ schrieb Simon Glass > > >> > > > > > > >>>>> <s...@chromium.org>: > > >> > > > > > > >>>>>> Hi, > > >> > > > > > > >>>>>> > > >> > > > > > > >>>>>> On Fri, 29 Oct 2021 at 13:26, Heinrich Schuchardt > > >> > > > > > > >>>>>> <xypron.g...@gmx.de> wrote: > > >> > > > > > > >>>>>>> > > >> > > > > > > >>>>>>> > > >> > > > > > > >>>>>>> > > >> > > > > > > >>>>>>> Am 29. Oktober 2021 08:15:56 MESZ schrieb AKASHI > > >> > > > > > > >>>>>>> Takahiro <takahiro.aka...@linaro.org>: > > >> > > > > > > >>>>>>>> On Fri, Oct 29, 2021 at 06:57:24AM +0200, Heinrich > > >> > > > > > > >>>>>>>> Schuchardt 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 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 > > >> > > > > > > >>>>>>>>>> below? 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 > > >> > > > > > > >>>>>>>>> interface. > > >> > > > > > > >>>>>>>>> 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 block 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 > > >> > > > > > > >>>>>>>>> because 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 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| 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 appear 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, 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 > > >> > > > > > > >>>>>>> mostly independent of the block device type we > > >> > > > > > > >>>>>>> should use separate uclasses and udevices. > > >> > > > > > > >>>>>>> > > >> > > > > > > >>>>>>>> I also remember that you claimed that not all efi > > >> > > > > > > >>>>>>>> objects(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_PARTITION_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_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_PARTITION_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 > > >> > > > > > > >>>>>>> exposing always only a single interface defined by > > >> > > > > > > >>>>>>> the uclass. > > >> > > > > > > >>>>>>> > > >> > > > > > > >>>>>>> The UEFI design allows installing multiple protocol > > >> > > > > > > >>>>>>> interfaces on a single handle. This may result in > > >> > > > > > > >>>>>>> simpler device trees in some cases. > > >> > > > > > > >>>>>> > > >> > > > > > > >>>>>> 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 filesystem, 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 > > >> > > > > > > >>>>> multiple 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 > > >> > > > > > > >>>> partitions 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 > > >> > > > > > > >>> reading 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 > > >> > > > > > > >>> step further > > >> > > > > > > >>> and create devices for them. > > >> > > > > > > >> > > >> > > > > > > >> Do you want to invent linux-like mount-point concepts or > > >> > > > > > > >> procfs? > > >> > > > > > > >> 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 > > >> > > > > > > > wrong thing > > >> > > > > > > > somewhere along the way. For example, a partition would be > > >> > > > > > > > under 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 device > > >> > > > > > > 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 > > >> > > > > > > hardware > > >> > > > > > > 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 > > >> > > > > > would > > >> > > > > > 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 > > >> > > > > > > harboring > > >> > > > > > > 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? > > > > > >As there has been no discussion in 5 days and Takahiro is writing > > >this, let's go with no uclass for the partition table. > > > > > > > Without uclass you cannot bring the partition table drivers into th driver > > model.
This transition may be able to be done later when really necessary as long as we agree that a partition table be hold within a "raw" disk object (with a tag support). # I don't think we need it for now. > > No clue what a tag should be in the driver model. > > A tag is a way to associate data with a device. At present we do this > with varoius built-in mechanisms (priv data, uclass-priv, plat, etc.) > but with tags you can add something else. Since this discussion thread is getting too long, I would like to respin my RFC. How should I deal with your "event notification" proposal? -Takahiro Akashi > Regards, > Simon