Armbian-install script fixes

[JohnTheCoolingFan]

Description

1. Set rootfstype in armbianEnv.txt in the boot from mtd, system on sata/nvme scenario
2. Add check for btrfs command when the btrfs filesystem is selected, and prompt the user whether to install it or not.

The first fix is an attempt to fix AR-2556 (armbian/config#233) but the original issue doesn't provide a way to reproduce, so i cannot verify if this does actually solve the issue. There's no mention of what boot method is used and where the root partition is installed to. If the rootfstype in /boot/armbianEnv.txt has no effect in the "boot from MTD" scenario, it could be excluded from this PR.

The btrfs check was introduced to make it more obvious what the issue is when the user select btrfs root and btrfs-progs package is not installed, as the script would only fail on "Partition too small" with Available: <empty string> MB as the message.

For the btrfs check, I have several points I'd like to get opinions on:

1. Is a dialog needed in the first place? Or should the script just install btrfs-progs if the user selected a btrfs filesystem?
2. Should the dialog stop the install process if the user denied installation?

How Has This Been Tested?

On Radxa Rock 5B+ with a sata ssd

• armbian-install with boot from MTD, selecting btrfs filesystem type and checking /boot/armbianEnv.txt in the resulting partition for rootfstype=btrfs
• armbian-install, selecting btrfs filesystem type for the root partition with and without btrfs-progs installed

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

[coderabbitai]

Walkthrough

The PR changes packages/bsp/common/usr/bin/armbian-install. For MTD boot paths, the script now sets or appends a rootfstype=<chosen filesystem> line in armbianEnv.txt in addition to updating rootdev. In format_disk, when the user selects btrfs and mkfs.btrfs is missing, the script prompts to run apt update/apt install btrfs-progs; it proceeds if the user agrees and verifies the binary exists, otherwise exits with an error code.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• Install to nvme: place root volume to separate subvolume on btrfs  #8108 — Also modifies btrfs handling in packages/bsp/common/usr/bin/armbian-install; overlaps with this PR’s changes to btrfs/rootfstype handling.

Suggested reviewers

• igorpecovnik

Pre-merge checks and finishing touches

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title Check	❓ Inconclusive	The PR title "Armbian-install script fixes" is related to the changeset but is overly generic and does not clearly highlight the primary modifications (setting rootfstype for MTD boot and adding a btrfs-progs check/install prompt), so it is inconclusive under the project's title guidelines.	Rename the title to a concise, specific line such as "armbian-install: set rootfstype for MTD boot and prompt to install btrfs-progs" so reviewers can quickly see the primary changes.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues Check	✅ Passed	The changes implement the coding objectives from AR-2556 by writing rootfstype into /boot/armbianEnv.txt for the MTD boot path and by adding a btrfs-progs presence check with an interactive install flow, which addresses missing tooling and improves diagnostics; however the author could not fully verify the runtime effect on boot and a reviewer requested testing with btrfs as a kernel module, so follow-up verification is recommended before closing the linked issue.
Out of Scope Changes Check	✅ Passed	All modifications are confined to the armbian-install script and directly relate to setting rootfstype or handling btrfs tooling; there are no unrelated file changes or functionality outside the linked issue objectives, so there are no out-of-scope changes.
Description Check	✅ Passed	The description documents the two code changes, motivation, test steps performed, and open reviewer questions, so it is directly related to the changeset and satisfies this lenient check.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment

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📥 Commits

Reviewing files that changed from the base of the PR and between be30ae2 and 6efe6ca.

📒 Files selected for processing (1)

• packages/bsp/common/usr/bin/armbian-install (2 hunks)

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/bsp/common/usr/bin/armbian-install

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[coderabbitai]

Actionable comments posted: 2

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

Disabled knowledge base sources:

• Jira integration is disabled by default for public repositories

You can enable these sources in your CodeRabbit configuration.

📥 Commits

Reviewing files that changed from the base of the PR and between 5c273e2 and be30ae2.

📒 Files selected for processing (1)

• packages/bsp/common/usr/bin/armbian-install (2 hunks)

🧰 Additional context used

🧠 Learnings (3)

📓 Common learnings

Learnt from: tabrisnet
PR: armbian/build#0
File: :0-0
Timestamp: 2025-08-30T06:56:33.372Z
Learning: In Armbian kernel configuration, the BTRFS configuration logic preserves existing settings (whether built-in 'y' or module 'm') and only sets BTRFS_FS to module when it was previously disabled or not set, achieving "allow but not require" flexibility while maintaining backward compatibility.

📚 Learning: 2025-09-01T06:11:43.476Z

Learnt from: wei633
PR: armbian/build#8557
File: config/bootscripts/boot-xpressreal-t3.cmd:0-0
Timestamp: 2025-09-01T06:11:43.476Z
Learning: In Armbian boot scripts without initramfs support, UUID= and LABEL= style device paths cannot be used for rootdev as they require initramfs to resolve during boot. Only direct device paths (/dev/mmcblkXpY) or PARTUUID= references (which U-Boot can resolve) will work.

Applied to files:

• packages/bsp/common/usr/bin/armbian-install

📚 Learning: 2025-06-04T23:45:38.860Z

Learnt from: djurny
PR: armbian/build#8272
File: config/bootscripts/boot-mvebu.cmd:182-186
Timestamp: 2025-06-04T23:45:38.860Z
Learning: In config/bootscripts/boot-mvebu.cmd, the `fdtfile` variable is mandatory for booting and is pre-set by U-Boot, but can be overridden via armbianEnv.txt. If `fdtfile` is empty, the subsequent device tree file search logic will eventually fail and trigger the critical error "Cannot find DT!" with proper error handling.

Applied to files:

• packages/bsp/common/usr/bin/armbian-install

[tabrisnet]

this isn't a blocker, just a request: can you test if this boots with btrfs built as a module, in re #8561 (comment)
and let me know?
I do expect it will work, but it'd be great to have confirmation vs #8561 (comment)

[JohnTheCoolingFan]

@tabrisnet unfortunately, I can't get the board to boot from MTD even with ext4. It's an issue I am also going to try and find the cause of. But right now I can probably only reproduce the boot from SD, root on sata case. If that's enough, I can try it.

[tabrisnet]

@tabrisnet unfortunately, I can't get the board to boot from MTD even with ext4. It's an issue I am also going to try and find the cause of. But right now I can probably only reproduce the boot from SD, root on sata case. If that's enough, I can try it.

sounds reasonable; please be sure to mention which FS are on boot & on root, esp in re this post.
Note that the u-boot Kconfig mentioned is a hair misleading, CMD_BTRFS isn't likely the operative part but rather FS_BTRFS. otoh, CMD_BTRFS implies FS_BTRFS so it's not incorrect.

[JohnTheCoolingFan]

Finally managed to install and boot, had to reconfigure u-boot.

Setting rootfstype is important with boot from MTD, which is what this PR fixes too.

Building a custom kernel to make btrfs a module.

[JohnTheCoolingFan]

@tabrisnet boots with root as btrfs, btrfs as module, no separate boot partition:

CONFIG_BTRFS_FS=m
CONFIG_BTRFS_FS_POSIX_ACL=y
# CONFIG_BTRFS_FS_RUN_SANITY_TESTS is not set
# CONFIG_BTRFS_DEBUG is not set
# CONFIG_BTRFS_ASSERT is not set
# CONFIG_BTRFS_EXPERIMENTAL is not set
# CONFIG_BTRFS_FS_REF_VERIFY is not set

[tabrisnet]

woohoo 🥳 🎉 Thank you for confirming. I've been on a bit of a "modulize all the things" kick in the Armbian kernel build system, and this is good info for some of the misgivings I had and was given by other maintainers. Mind you, my rule has been: either inessential to boot or inessential for basic functionality of the system/board; with a heavy focus on "will 90% of users use this functionality, or will making this thing a module adversely affect users of the board". Next question I need to solve: how much does zstd module [de]compression [on disc or in the initramfs] slow down boot on low end SOCs like the H5 or S905x. Sent from myPhone.