config: boards: pocketbeagle2: Add current-rt branch

[Ayush1325]

Description

Using RT kernel is a common thing on pocketbeagle 2. So add current-rt branch similar to what is being done for the base k3 family.

The current-rt config is just current config + PREEMPT_RT enabled.

How Has This Been Tested?

• First run setup and uname on PocketBeagle 2 rev A0.

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
• Any dependent changes have been merged and published in downstream modules

[coderabbitai]

Walkthrough

This change refactors the PocketBeagle 2 board configuration by introducing a helper function to centralize kernel and u-boot branch declarations. The previous function for handling the "current" branch override is replaced with a wrapper that calls this new helper, and support is added for a "current-rt" branch variant through a similar function. The "edge" branch function remains unchanged. Additionally, a new kernel configuration file for the "linux-k3-beagle-current-rt" variant is added, enabling a wide range of features, drivers, and subsystems for ARM64 with real-time preemption and K3 platform support.

Possibly related PRs

• Add current branch for PocketBeagle 2 #8370: Refactors and consolidates kernel and u-boot branch override functions for PocketBeagle 2, adding a helper function and support for the "current-rt" branch variant in the same configuration file.
• ti: config: kernel: Add current RT config file #8280: Adds a new "current-rt" kernel configuration file and integrates it into the TI K3 kernel build system, directly related to handling the "current-rt" kernel branch variant in board and kernel configuration files.

Suggested labels

08, Needs review, size/large, Hardware

Suggested reviewers

• igorpecovnik
• Grippy98
• EvilOlaf

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📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 996e934 and f00fcc9.

📒 Files selected for processing (2)

• config/boards/pocketbeagle2.conf (2 hunks)
• config/kernel/linux-k3-beagle-current-rt.config (1 hunks)

🧰 Additional context used

🧠 Learnings (3)

📓 Common learnings

Learnt from: EvilOlaf
PR: armbian/build#8328
File: lib/functions/compilation/patch/drivers_network.sh:542-545
Timestamp: 2025-06-24T10:08:40.313Z
Learning: In the Armbian build system, when a PR removes build support for a specific kernel version, version check issues for that removed version become practically irrelevant even if they appear incorrect in isolation. Context about which kernel versions are being deprecated/removed is important for understanding the impact of version-related code changes.

Learnt from: rpardini
PR: armbian/build#8044
File: patch/u-boot/v2025.04/cmd-fileenv-read-string-from-file-into-env.patch:76-86
Timestamp: 2025-03-31T22:20:48.475Z
Learning: For the Armbian build project, maintaining consistency with existing patches across U-Boot versions (such as between 2025.01 and 2025.04) is prioritized over refactoring individual patches for code improvements.

Learnt from: The-going
PR: armbian/build#8147
File: config/sources/families/include/sunxi64_common.inc:38-39
Timestamp: 2025-04-30T16:16:47.150Z
Learning: The Armbian build system references Linux kernel versions in the form "tag:v6.14.4" in the KERNELBRANCH variable, even when point release tags might not be directly visible in the upstream repository in the same form.

Learnt from: rpardini
PR: armbian/build#8044
File: patch/u-boot/v2025.04/cmd-fileenv-read-string-from-file-into-env.patch:73-75
Timestamp: 2025-03-31T22:20:41.849Z
Learning: When porting patches between U-Boot versions (like from 2025.01 to 2025.04), rpardini prefers to maintain patches as-is rather than introducing refactoring changes, even when potential improvements are identified. This approach prioritizes consistency and reduces the risk of introducing new issues.

Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:42:09.086Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, KERNELSOURCE is explicitly declared when using unofficial or 3rd party kernel repositories (like the "dev" branch using https://github.com/apritzel/linux), but can be omitted when using the standard mainline kernel (like the "edge" branch) since it will fall back to the default mainline source.

Learnt from: libiunc
PR: armbian/build#8033
File: config/kernel/linux-starfive2-vendor.config:43-43
Timestamp: 2025-03-31T12:57:13.880Z
Learning: For StarFive2 platform kernel configurations, maintain alignment with vendor-provided configurations rather than modifying security settings like SECCOMP. This ensures hardware compatibility as intended by the manufacturer.

Learnt from: pyavitz
PR: armbian/build#8361
File: config/kernel/linux-sunxi64-edge.config:594-597
Timestamp: 2025-07-06T16:27:45.349Z
Learning: In Armbian sunxi64-edge kernel configurations, PCI/PCIe support may be enabled for future-proofing purposes to support upcoming Allwinner SoCs like the T536 that include PCIe Gen2 interfaces, even if current primary targets like H616 lack PCIe controllers. This forward-looking approach prepares the configuration for next-generation hardware in the same SoC family.

Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:40:52.109Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, when KERNELSOURCE is not explicitly declared in a case branch, the system falls back to a default KERNELSOURCE value, so missing KERNELSOURCE declarations are not critical issues.

Learnt from: djurny
PR: armbian/build#8287
File: config/bootscripts/boot-sunxi.cmd:148-161
Timestamp: 2025-06-12T21:03:39.686Z
Learning: In Armbian U-Boot bootscripts, the `${cpu}` environment variable is always pre-set by U-Boot (or defaults to a valid value), so additional guards against it being unset are unnecessary.

config/boards/pocketbeagle2.conf (10)

Learnt from: rpardini
PR: armbian/build#8044
File: patch/u-boot/v2025.04/cmd-fileenv-read-string-from-file-into-env.patch:73-75
Timestamp: 2025-03-31T22:20:41.849Z
Learning: When porting patches between U-Boot versions (like from 2025.01 to 2025.04), rpardini prefers to maintain patches as-is rather than introducing refactoring changes, even when potential improvements are identified. This approach prioritizes consistency and reduces the risk of introducing new issues.

Learnt from: rpardini
PR: armbian/build#8044
File: patch/u-boot/v2025.04/cmd-fileenv-read-string-from-file-into-env.patch:76-86
Timestamp: 2025-03-31T22:20:48.475Z
Learning: For the Armbian build project, maintaining consistency with existing patches across U-Boot versions (such as between 2025.01 and 2025.04) is prioritized over refactoring individual patches for code improvements.

Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:42:09.086Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, KERNELSOURCE is explicitly declared when using unofficial or 3rd party kernel repositories (like the "dev" branch using https://github.com/apritzel/linux), but can be omitted when using the standard mainline kernel (like the "edge" branch) since it will fall back to the default mainline source.

Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:40:52.109Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, when KERNELSOURCE is not explicitly declared in a case branch, the system falls back to a default KERNELSOURCE value, so missing KERNELSOURCE declarations are not critical issues.

Learnt from: djurny
PR: armbian/build#8287
File: config/bootscripts/boot-sunxi.cmd:38-44
Timestamp: 2025-06-12T21:14:36.024Z
Learning: In config/bootscripts/boot-sunxi.cmd the unconditional "+1" increment in func_align_addr_next (when align_overlap_oboe_avoidance="on") is intentional. It compensates for a known off-by-one error in U-Boot where the end address is calculated as start+size instead of start+size-1, so the extra page prevents overlap. This behavior should not be “optimized away”.

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.

Learnt from: The-going
PR: armbian/build#8147
File: config/sources/families/include/sunxi64_common.inc:38-39
Timestamp: 2025-04-30T16:16:47.150Z
Learning: The Armbian build system references Linux kernel versions in the form "tag:v6.14.4" in the KERNELBRANCH variable, even when point release tags might not be directly visible in the upstream repository in the same form.

Learnt from: Grippy98
PR: armbian/build#8152
File: lib/functions/configuration/interactive.sh:209-266
Timestamp: 2025-05-05T12:35:07.143Z
Learning: For the interactive kernel selection in Armbian, KERNEL_MAJOR_MINOR and KERNEL_DESCRIPTION are parsed from family.conf but deliberately not set as environment variables to avoid potential interference with other parts of the build system.

Learnt from: djurny
PR: armbian/build#8287
File: config/bootscripts/boot-sunxi.cmd:148-161
Timestamp: 2025-06-12T21:03:39.686Z
Learning: In Armbian U-Boot bootscripts, the `${cpu}` environment variable is always pre-set by U-Boot (or defaults to a valid value), so additional guards against it being unset are unnecessary.

Learnt from: libiunc
PR: armbian/build#8033
File: config/kernel/linux-starfive2-vendor.config:43-43
Timestamp: 2025-03-31T12:57:13.880Z
Learning: For StarFive2 platform kernel configurations, maintain alignment with vendor-provided configurations rather than modifying security settings like SECCOMP. This ensures hardware compatibility as intended by the manufacturer.

config/kernel/linux-k3-beagle-current-rt.config (5)

Learnt from: libiunc
PR: armbian/build#8033
File: config/kernel/linux-starfive2-vendor.config:43-43
Timestamp: 2025-03-31T12:57:13.880Z
Learning: For StarFive2 platform kernel configurations, maintain alignment with vendor-provided configurations rather than modifying security settings like SECCOMP. This ensures hardware compatibility as intended by the manufacturer.

Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:42:09.086Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, KERNELSOURCE is explicitly declared when using unofficial or 3rd party kernel repositories (like the "dev" branch using https://github.com/apritzel/linux), but can be omitted when using the standard mainline kernel (like the "edge" branch) since it will fall back to the default mainline source.

Learnt from: EvilOlaf
PR: armbian/build#8330
File: config/sources/families/sun55iw3.conf:32-36
Timestamp: 2025-06-25T03:40:52.109Z
Learning: In Armbian build system configuration files like config/sources/families/*.conf, when KERNELSOURCE is not explicitly declared in a case branch, the system falls back to a default KERNELSOURCE value, so missing KERNELSOURCE declarations are not critical issues.

Learnt from: EvilOlaf
PR: armbian/build#0
File: :0-0
Timestamp: 2025-06-16T03:24:00.458Z
Learning: In Armbian board configuration files (.csc), the standard pattern is to have only one line as a comment describing the board hardware specifications. This single-line description typically includes the SoC model, core count, RAM options, and key features like connectivity options, storage interfaces, and special features.

Learnt from: pyavitz
PR: armbian/build#8361
File: config/kernel/linux-sunxi64-edge.config:594-597
Timestamp: 2025-07-06T16:27:45.349Z
Learning: In Armbian sunxi64-edge kernel configurations, PCI/PCIe support may be enabled for future-proofing purposes to support upcoming Allwinner SoCs like the T536 that include PCIe Gen2 interfaces, even if current primary targets like H616 lack PCIe controllers. This forward-looking approach prepares the configuration for next-generation hardware in the same SoC family.

🔇 Additional comments (6)

config/kernel/linux-k3-beagle-current-rt.config (3)

8-8: LGTM! Real-time preemption correctly enabled.

The CONFIG_PREEMPT_RT=y setting properly enables real-time kernel support as required for the current-rt branch.

---

106-955: Comprehensive configuration appropriate for development board.

The extensive enablement of networking, storage, USB, graphics, audio, and other subsystems provides excellent hardware compatibility for PocketBeagle 2. The configuration balances functionality with the real-time requirements.

---

940-955: Well-balanced debug configuration for RT kernel.

The debug settings appropriately enable useful development features while disabling FTRACE to maintain real-time performance characteristics.

config/boards/pocketbeagle2.conf (3)

20-28: Excellent refactoring to eliminate code duplication.

The helper function centralizes common kernel and u-boot source declarations, making the configuration more maintainable. Using the same kernel source with different configurations for RT vs non-RT variants is a sensible approach.

---

31-34: Clean refactoring maintains backward compatibility.

The updated function properly delegates to the helper while maintaining the same interface and providing clear user feedback about the branch override.

---

36-39: Perfect implementation of current-rt branch support.

The new function follows the established pattern and naming conventions while providing clear feedback about the RT branch override. This directly supports the PR objective of enabling real-time kernel support.

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