nor: the split layout is a uImage + squashfs, and the kernel is told nothing

[widgetii]

The split NOR layout was a FIT followed by the squashfs, which only a
FIT-capable U-Boot boots, and the kernel learned its partitions and root
from the mtdparts and root= this bootloader passed. Both move to the
kernel (OpenIPC/linux): the gk7205v200 family's device tree carries the
layout, mtdsplit divides a uImage followed by the squashfs, and the root
the split finds is taken whatever root= says. So any U-Boot that can
bootm a uImage at 0x50000 boots the layout -- the factory XM one
included -- and this one only has to stop telling the kernel otherwise.

• The split layout is recognised as a uImage at the kernel offset with
  the scan's squashfs at the next 64 KiB block after it; fixed slots put
  the squashfs at the slot boundary.
• On it, mtdparts=, root= and openipc_nor_fit= are dropped from bootargs
  (RAM only), and verify is unset so bootm checks the uImage CRC.
  kernsize/rootaddr/rootsize keep naming the fixed slots for uk/ur.
• CONFIG_OPENIPC_NOR_FIT_SPLIT becomes CONFIG_OPENIPC_NOR_SPLIT, with no
  FIT dependency; CONFIG_SHA1 leaves the four fragments. NOR images
  210-211 KB (gk7205v200/v300), down from 222.

FIT split images are no longer recognised: none were released outside
the 2026-10-17 nightly.

Tested in QEMU (qemu-hisilicon gk7205v200): the split image boots with
"mem=32M console=ttyAMA0,115200 panic=20 rootfstype=squashfs init=/init"
and "Verifying Checksum ... OK"; the fixed-slot package keeps its
mtdparts and root=/dev/mtdblock3.

On hardware: flashed on a GK7205V300 (16 MB NOR), it boots the split
uImage with "Verifying Checksum ... OK" and the same clean command line;
the kernel splits firmware from its device tree, overlay rw, majestic up.

Kernel side: OpenIPC/linux#97 (merged). Firmware side: OpenIPC/firmware#2623 (merged).

[qodo-free-for-open-source-projects]

PR Summary by Qodo

Boot split NOR firmware as uImage with kernel-managed partitions

✨ Enhancement ⚙️ Configuration changes 🕐 20-40 Minutes

AI Description

• Recognize split NOR firmware by its uImage and adjacent squashfs, enabling boot with
 uImage-capable U-Boot.
• Remove legacy partition and root arguments for split boots; retain fixed-slot upgrade settings and
 checksum verification.
• Enable the new layout on four boards without FIT or SHA1 dependencies.

Diagram

graph TD
  CFG["Board configs"] --> SCAN["NOR flash scan"] --> LAYOUT{"Split layout?"}
  LAYOUT -->|yes| SPLIT["Strip legacy args"] --> BOOT["Boot uImage"] --> LINUX["Linux rootfs"]
  LAYOUT -->|no| FIXED["Keep fixed slots"] --> BOOT

Loading

High-Level Assessment

The following are alternative approaches to this PR:

1. Keep FIT and upgrade bootloaders

• ➕ Retains FIT-based kernel and device-tree hash verification.
• ➖ Excludes factory U-Boot implementations that can boot a uImage but not FIT.
• ➖ Requires a bootloader replacement to use split firmware.

Recommendation: Prefer the uImage approach because compatibility with factory U-Boot is the central goal. Relying on the kernel's device tree for split partitions also avoids passing a layout that may be stale in saved boot arguments; review the FIT compatibility tradeoff explicitly.

Files changed (6) +116 / -116

Enhancement (1) +95 / -91

openipc.cDetect split uImage firmware and clean its boot environment +95/-91

Detect split uImage firmware and clean its boot environment

• Recognizes split firmware when the scanned squashfs follows the uImage at the next 64 KiB boundary. For split boots, removes legacy boot arguments, enables uImage CRC verification, and keeps fixed-slot addresses for upgrade commands; the fixed-layout path no longer rewrites root arguments.

common/openipc.c

Other (5) +21 / -25

KconfigDefine uImage-based split NOR support +9/-9

Define uImage-based split NOR support

• Replaces the FIT-specific option with CONFIG_OPENIPC_NOR_SPLIT and removes its FIT dependency. Documents kernel-managed partitions and the requirement for a compatible board kernel.

common/Kconfig

xm72020300_configEnable uImage split NOR on xm72020300 +3/-4

Enable uImage split NOR on xm72020300

• Selects CONFIG_OPENIPC_NOR_SPLIT instead of FIT-specific split support and removes FIT and SHA1 selections.

openipc/xm72020300_config

xm72050200_configEnable uImage split NOR on xm72050200 +3/-4

Enable uImage split NOR on xm72050200

• Selects CONFIG_OPENIPC_NOR_SPLIT instead of FIT-specific split support and removes FIT and SHA1 selections.

openipc/xm72050200_config

xm72050300_configEnable uImage split NOR on xm72050300 +3/-4

Enable uImage split NOR on xm72050300

• Selects CONFIG_OPENIPC_NOR_SPLIT instead of FIT-specific split support and removes FIT and SHA1 selections.

openipc/xm72050300_config

xm76050100_configEnable uImage split NOR on xm76050100 +3/-4

Enable uImage split NOR on xm76050100

• Selects CONFIG_OPENIPC_NOR_SPLIT instead of FIT-specific split support and removes FIT and SHA1 selections.

openipc/xm76050100_config

[qodo-free-for-open-source-projects]

Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0) 🎨 UX issues (0) 🔗 Cross-repo conflicts (0) 📜 Skill insights (0)

1. Some fixed-slot cameras lose their root ✓ Resolved

Description

nor_split_layout() treats a fixed-slot image as split when its uImage ends within the final 64 KiB
of the kernel slot, because the aligned image length then equals the slot size. On these images, the
split branch removes the fixed layout’s root= and mtdparts= arguments even though the squashfs
is at the normal fixed-slot boundary.

Code

common/openipc.c[554]

+  return rootfs_off == kernel_off + ALIGN(image_get_image_size(&hdr), 0x10000);

Evidence

The fixed layouts put the rootfs 2 MiB or 3 MiB after the kernel. A uImage length in the last 64 KiB
of either slot rounds up to exactly that offset, satisfying the new split test; that branch then
deletes the default arguments identifying the fixed root and partitions.

common/openipc.c[546-555]
common/openipc.c[509-535]
common/openipc.c[631-678]
include/configs/openipc-common.h[169-169]
include/configs/openipc-common.h[183-185]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
A fixed-slot uImage that fills all but the final 64 KiB of its kernel slot satisfies the new split-layout test. The split branch then removes the root and partition arguments required by that fixed layout.
## Fix Focus Areas
- common/openipc.c[546-555]
- common/openipc.c[631-678]
## Recommended Fix
Do not infer a split layout solely from equality between the aligned uImage length and a fixed-slot rootfs offset. Add a reliable distinguishing check before stripping boot arguments, and test uImages ending in the last 64 KiB of both supported fixed kernel slots.

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