PrawnOS Documentation

Some additional documentation for PrawnOS that wouldn't fit in the README

Useful XFCE4 keybindings and libinput-gestures:

Gestures:

Config file: /etc/libinput-gestures.conf

four finger swipe left: Switch to left workspace
four finger swipe right: Switch to right worksace

Keybindings

Configure under Settings->Window Manager->Keyboard

control+alt+left: move window to left workspace
control+alt+right: move window to right workspace
control+left: tile widow to the left
control+right: tile window to the right
control+up: maximize window
alt+tab: app switcher

Configure under Settings->Keyboard->Application Shortcuts

alt+space : App launcher (spotlight-esque)
control+alt+l: Lock screen
Brightness scripts are also called here and can be remapped here or in ~/.Xmodmap

Configured using ~/.Xmodmap

"search" key: Mode switch aka m_s (function key)
m_s + backspace: delete
m_s + up: page up
m_s + down: page down
m_s + left: home
m_s + right: end
m_s + period: insert
"brightness up key": increase backlight
"brightness down key": decrease backlight
"volume mute": mute volume
"volume down": decrease volume
"volume up": increase volume
m_s + "brightness up key": F7
m_s + "brightness down key": F6
m_s + "volume mute key": F8
m_s + "volume down key": F9
m_s + "volume up key": F10

Configured using ~/.xinputrc

alt+left left a word
alt+right right a word

Initramfs and Encryption

PrawnOS uses a custom initramfs, custom init script, and dmcrypt/LUKS to enable full root partition encryption

Because the c201s bootloader, depthcharge, can't be given dynamic cmdline parameters like grub we can't use the "usual" method of setting up an initramfs. Essentially, we can't boot from an initramfs image stored on a /boot partiton

Either the initramfs needs to be built into the part of the kernel image passed to depthcharge using a kernel.its similar to this one by @ifbizo:

/dts-v1/;

/ {
	description = "Linux-libre kernel image with one or more FDT blobs";
	#address-cells = <1>;
	images {
		kernel {
			description = "vmlinuz";
			data = /incbin/("/boot/vmlinuz-SED_KVER");
			type = "kernel_noload";
			arch = "arm";
			os = "linux";
			compression = "none";
			load = <0>;
			entry = <0>;
			hash {
				algo = "sha1";
			};
		};
		fdt {
			description = "dtb";
			data = /incbin/("/boot/rk3288-veyron-speedy.dtb");
			type = "flat_dt";
			arch = "arm";
			compression = "none";
			hash {
				algo = "sha1";
			};
		};
		ramdisk@1{
			description = "initrd.img";
			data = /incbin/("/boot/initrd.img-SED_KVER");
			type = "ramdisk";
			arch = "arm";
			os = "linux";
			compression = "none";
			hash@1{
				algo = "sha1";
			};
		};
	};
	configurations {
		default = "conf";
		conf{
			kernel = "kernel";
			fdt = "fdt";
			ramdisk = "ramdisk@1";
		};
	};
};

Or it needs to be built into the kernel using the kernel config parameter CONFIG_INITRAMFS_SOURCE="PrawnOS-initramfs.cpio.gz"

For PrawnOS I decided to go with building into the kernel to avoid relying on the bootloader, the bootloader may change but the kernel will always support booting an initramfs image.

The script buildInitramFs.sh creates the PrawnOS-initramfs.cpio.gz image that is then used by buildKerenl.sh, copying all of the tools and libraries the initramfs needs from the built filesystem image.

The initramfs is what runs initialy at boot, and allows us to enter a password and decrypt the root partiton

In a normal system, when dmcrypt/LUKS is setup the initramfs image is modified to enable decrypting of the root partiton

Since we have to have a static initramfs image, and can't change it without recompiling the kernel, we have to be a little crafty to support unencrypted and encrypted root partitons with the same initramfs

This is achieved by placing flags in the /boot partition, aka /dev/mmcblk2p2 or /dev/sda2. The /boot partiton is empty on an unencrypted system. When root encryption is set up, the file root_encryption is created, which the initramfs init script uses to determine that it should try and decrypt the root partiton

debugging the init script

A rescue debug shell is entered when the init script encounters a problem, or if the debug flag is set

You can enable the debug flag by mounting /boot and creating a file named debug

To make the system boot normally, from the debug prompt, run rm /boot/debug and exit to reboot

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