[PATCH v2 0/7] fit: dm-verity support

[Daniel Golle]

On Thu, Apr 23, 2026 at 02:59:19PM +0200, Rasmus Villemoes wrote:
> On Thu, Apr 16 2026, Daniel Golle <daniel at makrotopia.org> wrote:
> 
> > This series adds dm-verity support to U-Boot's FIT image infrastructure.
> > It is the first logical subset of the larger OpenWrt boot method series
> > posted as an RFC in February 2026 [1], extracted here for independent
> > review and merging.
> >
> > OpenWrt's firmware model embeds a read-only squashfs or erofs root
> > filesystem directly inside a uImage.FIT container as a FILESYSTEM-type
> > loadable FIT image. At boot the kernel maps this sub-image directly from
> > the underlying block device via the fitblk driver (/dev/fit0, /dev/fit1,
> 
> Can you show me where that fitblk driver lives, because I can't find
> anything like that in the linux source code. Grepping for 'fitblk' or
> 'dev/fit' turns up nothing.

The driver is currently downstream, but going to be (re-)submitted upsteam.
See below for more.

> 
> > ...), the goal is that the bootloader never even copies it to RAM.
> 
> Hm, how is that achieved? I.e., how do you load and boot the FIT image
> without loading that part, but still reading in e.g. the kernel?

The next series after this is going to suggest a way for on-demand
loading only the actually necessary FIT images from a storage backend.
See
https://github.com/u-boot/u-boot/pull/870

And see here for an end-to-end demo:
https://github.com/openwrt/openwrt/pull/22177