rpi4b: fix build and boot issues

[EvilOlaf]

Description

Follow-up of #9097

It was reported that legacy doesn't build and current doesn't boot. This should fix both.

kernel config rewrite pending to get back in sync

How Has This Been Tested?

• build and boot current (6.18.4 atm)
• build legacy

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

Summary by CodeRabbit

• New Features
  • Broader hardware support: many new display panels, codecs, audio subsystem drivers, sensors, RTCs and thermal drivers.
  • Expanded virtualization support: additional VirtIO and VMCI-related device options for virtual environments.
  • Improved CPU/architecture handling and errata mitigations for ARM64 platforms; higher CPU count support.
  • Enhanced networking, security and crypto primitives; expanded firewall/NF flow and NFS/auth integrations.
  • More I2C/SPI/GPIO/USB/PCI and power/regulator driver coverage for varied boards.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Updates to BCM2711 kernel configuration files adding many ARM64 erratum mitigations, expanded VirtIO/SCSI/VIRTIO_NET support, broader DRM/display and I2C/SPI/peripheral drivers, network/NF_TABLES changes, audio/thermal/RTC additions, and various power/regulator and crypto option expansions across current and legacy configs.

Changes

Cohort / File(s)	Change Summary
Core kernel config config/kernel/linux-bcm2711-current.config, config/kernel/linux-bcm2711-legacy.config	Large rework of kernel config entries: new ARM64 errata options, CONFIG_NR_CPUS=256, KPROBES enabled, many crypto primitives added, PROC_CHILDREN/CACHEFILES toggles.
VirtIO / Virtualization config/kernel/linux-bcm2711-current.config, config/kernel/linux-bcm2711-legacy.config	Added/enabled VirtIO components: VIRTIO_VSOCKETS, VIRTIO_BALLOON, VIRTIO_INPUT, VIRTIO_NET, SCSI_VIRTIO, I2C_VIRTIO, and related modules; some VSOCKET variants replaced with VMCI in legacy.
Networking / Netfilter config/kernel/linux-bcm2711-current.config, config/kernel/linux-bcm2711-legacy.config	NET_CLS_BPF mode change; NF_TABLES / NF_FLOW_TABLE entries expanded (PROCFS/INET/NETDEV), MPTCP and NETWORK_PHY_TIMESTAMPING added; various conntrack/table toggles adjusted.
Display / DRM / Panels config/kernel/linux-bcm2711-current.config, config/kernel/linux-bcm2711-legacy.config	New DRM drivers and panel connectors (ICN6211, IT6505, LT8912B, LT9211, LT9611UXC, IT66121, TI DLPC3433, SN65DSI83, ANALOGIX_ANX7625), expanded VC4/RP1 DSI/DPIs and panel support.
I2C / SPI / GPIO / Sensors config/kernel/linux-bcm2711-current.config, config/kernel/linux-bcm2711-legacy.config	Many I2C/SPI/GPIO drivers added (I2C_BCM*, SPI_BCM2835, I2C_CP2615, etc.), sensor/thermal/RTC drivers and IIO trigger entries expanded.
Audio / Sound config/kernel/linux-bcm2711-legacy.config	Large ASoC and SND expansions: SND_BCM2835_SOC_I2S, many SND_SOC_* drivers, audio graph/card samples and codecs.
Power / Regulators / Platform config/kernel/linux-bcm2711-current.config, config/kernel/linux-bcm2711-legacy.config	Added RP1/Raspberry Pi power and regulator options, RASPBERRYPI_POWER, ARM_RASPBERRYPI_CPUFREQ, NUMA, CHECKPOINT_RESTORE, PSI_DEFAULT_DISABLED, and COMMON_CLK_RP1_SDIO adjustments.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• filogic/bpi-r4 - fix edge kernel config #8772 — overlapping kernel config edits including USB_NET_RNDIS_HOST and other kernel options.
• linux-uefi-arm64-cloud.config: enable ACPI so things boot #8377 — similar enabling of VirtIO/SCSI_VIRTIO/VIRTIO_NET/BALLOON-related config entries.
• rpi4b: bump _edge_ to 6.18 #8845 — modifies BCM2711 configs with overlapping HOTPLUG_CPU and RP1/pinctrl-related options.

Suggested labels

BSP

Suggested reviewers

• PanderMusubi
• teknoid
• igorpecovnik
• rpardini

Poem

🐰
I hopped through configs, line by line,
Errata, VirtIO, displays that shine,
I2C, sound, and power too,
BCM2711 — fresh and new,
A tiny rabbit cheers — code fine! 🥕✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main purpose of the PR: fixing build and boot issues for RPi4B kernel configurations.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@config/kernel/linux-bcm2711-legacy.config`:
- Around line 469-471: Add the missing CONFIG_VIRTIO_VSOCKETS option to the
legacy bcm2711 kernel config so vsockets have the virtio transport;
specifically, insert CONFIG_VIRTIO_VSOCKETS=m alongside the existing
CONFIG_VSOCKETS=m / CONFIG_VMWARE_VMCI_VSOCKETS=m / CONFIG_NETLINK_DIAG=m block
(and apply the same insertion at the other occurrence later in the file) so both
vsocket sections include the virtio transport option.

🧹 Nitpick comments (2)

config/kernel/linux-bcm2711-current.config (1)

553-553: RP1/BCM2712 options are included from Raspberry Pi's upstream kernel—verify whether to keep them aligned with upstream or trim for Pi 4 only.

The kernel config includes RP1/BCM2712-specific options (CONFIG_MISC_RP1=y, CONFIG_PINCTRL_BCM2712=y, CONFIG_SENSORS_RP1_ADC=m, CONFIG_MFD_RP1=y, CONFIG_VIDEO_RP1_CFE=m, CONFIG_DRM_RP1_DSI=m, CONFIG_DRM_RP1_DPI=m, CONFIG_DRM_RP1_VEC=m, CONFIG_COMMON_CLK_RP1_SDIO=m, CONFIG_BCM2712_IOMMU=y, CONFIG_PWM_RP1=m, CONFIG_BCM2712_MIP=y). These are sourced from Raspberry Pi's official kernel branches (rpi-6.18.y for current), which support multiple board versions in a single kernel. Since Armbian currently supports only Pi 4, these options compile unused code. However, keeping them aligns with Raspberry Pi's upstream approach. Consider whether the maintenance benefit of staying synchronized with upstream outweighs the code bloat.

config/kernel/linux-bcm2711-legacy.config (1)

2419-2438: Confirm debug-heavy options are intended for release configs.

BOOT_PRINTK_DELAY, KGDB/KDB, LATENCYTOP, DETECT_HUNG_TASK, and relaxed STRICT_DEVMEM can impact boot time and security posture. If these were only for diagnosing boot issues, consider moving them to a debug flavor.

[igorpecovnik]

perhaps also fix that Rabbit's suggestion for legacy?

[github-actions]

✅ This PR has been reviewed and approved — all set for merge!