Custom Linux Command Line

When booting Linux, it is often necessary for developers to tweak the kernel command line parameters on the fly. Repacking the KERNEL just to change a bootarg is time-consuming.

To solve this, ROCKNIX-ABL includes a feature that dynamically reads command-line overrides directly from text files placed on any FAT32 partition.

This only applies if you are using an Android boot image and not if you are booting a UEFI application (e.g., Grub).

How It Works

During the boot process, right before the ABL passes execution to the kernel, it scans all attached FAT32 filesystems for two specific files:

• cmdline.txt
• cmdline-append.txt

1. cmdline.txt (Full Override)

If this file is found, its contents will completely overwrite the default command line contained in the boot image. Use this when you want total control over the kernel parameters.

2. cmdline-append.txt (Append)

If this file is found, its contents will be appended to the end of the existing command line. Use this to add temporary flags (e.g., init=/bin/bash, loglevel=7) without losing the arguments contained in the boot image.

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Usage Instructions

1. Mount your device's FAT32 partition on your PC.
2. Create a standard text file named cmdline.txt or cmdline-append.txt at the root of the drive.
3. Add your desired kernel parameters.

• Example: root=/dev/mmcblk0p2 rw quiet splash

4. Save the file and boot the device.