On 2/23/26 22:24, Daniel Golle wrote:
> On Mon, Feb 23, 2026 at 10:51:09AM -0700, Simon Glass wrote:
>> Hi Daniel,
>>
>> On Thu, 19 Feb 2026 at 09:51, Daniel Golle <[email protected]> wrote:
>>> On Thu, Feb 19, 2026 at 06:09:27AM -0700, Simon Glass wrote:
>>>> Hi Daniel,
>>>>
>>>> On Mon, 16 Feb 2026 at 14:22, Daniel Golle <[email protected]> wrote:
>>>>> Add a UBI volume storage backend for the image_loader framework.
>>>>>
>>>>> image_loader_init_ubi() takes a volume name, ensures the UBI device
>>>>> is attached (auto-attaching if needed), and installs a .read() callback
>>>>> wrapping ubi_volume_read().
>>>>>
>>>>> Auto-attach works by scanning the device tree for the first MTD
>>>>> partition with compatible = "linux,ubi", then calling ubi_part() on
>>>>> that partition. The partition name is resolved using the same
>>>>> precedence as the MTD partition parser: the "label" property first,
>>>>> then "name", then the node name. Since U-Boot only supports a single
>>>>> attached UBI device at a time, only the first matching partition is
>>>>> used. If a UBI device is already attached, the auto-attach step is
>>>>> skipped.
>>>>>
>>>>> UBI handles bad-block management and wear leveling internally, so the
>>>>> read callback is a straightforward passthrough. Note that
>>>>> ubi_volume_read() returns positive errno values; the wrapper negates
>>>>> them for the image_loader convention.
>>>>>
>>>>> Gated by CONFIG_IMAGE_LOADER_UBI (depends on CMD_UBI && IMAGE_LOADER).
>>>>>
>>>>> Signed-off-by: Daniel Golle <[email protected]>
>>>>> ---
>>>>> boot/Kconfig | 8 +++
>>>>> boot/Makefile | 1 +
>>>>> boot/image-loader-ubi.c | 112 ++++++++++++++++++++++++++++++++++++++++
>>>>> include/image-loader.h | 13 +++++
>>>>> 4 files changed, 134 insertions(+)
>>>>> create mode 100644 boot/image-loader-ubi.c
>>>>>
>>>>> diff --git a/boot/Kconfig b/boot/Kconfig
>>>>> index 23848a0f57e..89832014af6 100644
>>>>> --- a/boot/Kconfig
>>>>> +++ b/boot/Kconfig
>>>>> @@ -1203,6 +1203,14 @@ config IMAGE_LOADER_MTD
>>>>> parallel NAND, etc.) using the image_loader framework.
>>>>> NAND bad blocks are skipped transparently.
>>>>>
>>>>> +config IMAGE_LOADER_UBI
>>>>> + bool "UBI volume backend for image loader"
>>>>> + depends on IMAGE_LOADER && CMD_UBI
>>>>> + help
>>>>> + Allows loading images from UBI volumes using the image_loader
>>>>> + framework. Auto-attaches the UBI device from the device tree
>>>>> + if not already attached.
>>>>> +
>>>>> config DISTRO_DEFAULTS
>>>>> bool "(deprecated) Script-based booting of Linux distributions"
>>>>> select CMDLINE
>>>>> diff --git a/boot/Makefile b/boot/Makefile
>>>>> index 1dde16db694..7d1d4a28106 100644
>>>>> --- a/boot/Makefile
>>>>> +++ b/boot/Makefile
>>>>> @@ -76,6 +76,7 @@ obj-$(CONFIG_$(PHASE_)BOOTMETH_ANDROID) +=
>>>>> bootmeth_android.o
>>>>> obj-$(CONFIG_IMAGE_LOADER) += image-loader.o
>>>>> obj-$(CONFIG_IMAGE_LOADER_BLK) += image-loader-blk.o
>>>>> obj-$(CONFIG_IMAGE_LOADER_MTD) += image-loader-mtd.o
>>>>> +obj-$(CONFIG_IMAGE_LOADER_UBI) += image-loader-ubi.o
>>>>>
>>>>> obj-$(CONFIG_$(PHASE_)BOOTMETH_VBE_ABREC) += vbe_abrec.o vbe_common.o
>>>>> obj-$(CONFIG_$(PHASE_)BOOTMETH_VBE_ABREC_FW) += vbe_abrec_fw.o
>>>>> diff --git a/boot/image-loader-ubi.c b/boot/image-loader-ubi.c
>>>>> new file mode 100644
>>>>> index 00000000000..64901a13378
>>>>> --- /dev/null
>>>>> +++ b/boot/image-loader-ubi.c
>>>>> @@ -0,0 +1,112 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0+
>>>>> +/*
>>>>> + * UBI volume backend for image_loader
>>>>> + *
>>>>> + * Copyright (C) 2026 Daniel Golle <[email protected]>
>>>>> + */
>>>>> +
>>>>> +#include <dm/ofnode.h>
>>>>> +#include <image-loader.h>
>>>>> +#include <log.h>
>>>>> +#include <malloc.h>
>>>>> +#include <mtd.h>
>>>>> +#include <ubi_uboot.h>
>>>>> +
>>>>> +struct image_loader_ubi_priv {
>>>>> + char *vol_name;
>>>>> +};
>>>>> +
>>>>> +/**
>>>>> + * ubi_auto_attach() - attach UBI if not already attached
>>>>> + *
>>>>> + * If no UBI device is currently attached, walk the device tree for the
>>>>> + * first MTD partition node with compatible = "linux,ubi", find the
>>>>> + * corresponding MTD device by matching flash_node, and attach UBI to
>>>>> + * it via ubi_part_from_mtd().
>>>>> + *
>>>>> + * Since U-Boot only supports a single attached UBI device at a time,
>>>>> + * only the first matching partition is used.
>>>>> + *
>>>>> + * Return: 0 on success or if already attached, negative errno on failure
>>>>> + */
>>>>> +static int ubi_auto_attach(void)
>>>>> +{
>>>>> + struct mtd_info *mtd;
>>>>> + ofnode node;
>>>>> +
>>>>> + /* Already attached? */
>>>>> + if (ubi_devices[0])
>>>>> + return 0;
>>>>> +
>>>>> + mtd_probe_devices();
>>>> This should be handled by your new ubi driver for your uclass.
>>>>
>>>>> +
>>>>> + ofnode_for_each_compatible_node(node, "linux,ubi") {
>>>>> + mtd_for_each_device(mtd) {
>>>>> + if (ofnode_equal(mtd->flash_node, node))
>>>>> + goto found;
>>>>> + }
>>>>> + }
>>>> Eek this is really strange. There should be a device so you can use
>>>> uclass_first_device(UCLASS_...).
>>> I carefully considered turning UBI devices into a UCLASS, but it would
>>> be a huge major rewrite of how UBI works in U-Boot, and while that would
>>> be a good thing to do, I consider far beyond the scope of supporting a
>>> boot method for OpenWrt.
>> Oh, I just assumed it supports driver model. But surely it must have a
>> UCLASS_BLK device?
> Sadly no. Neither UBI devices nor UBI volumes are block storage devices.
>
> Every UBI device does have a UCLASS_MTD parent device, but that
> obviously also doesn't uniquely identify the partition on the flash chip
> which is used as UBI device -- there can be (and sometimes are, for
> dual-boot/redundancy reasons) multiple UBI devices in different
> partitions on the same flash.
>
> What I ended up doing now is to move more of the UBI detection and
> enumeration logic into ubi_bootdev.c and have imagemap-ubi.c rely
> on getting the MTD device and partition index from there.
There are UBI based block storage emulation, see CONFIG_UBI_BLOCK
commits:
* 9daad11ad178646c288aca3615a7ba1e6039aed3 ("drivers: introduce UBI
block abstraction")
* aa5b67ce226267440e64fadc57d3a21e5842027c ("disk: support UBI partitions")
>>> Or did you mean the to-be-create UCLASS_IMAGE_MAPPER?
>> No I was talking about ubi.
>>
>> Regards,
>> Simon
