NixOS on ARM/Raspberry Pi 5: Difference between revisions

Line 32:

Support for the Raspberry Pi 5 is currently downstream and experimental.

'''Support for the Raspberry Pi 5 is currently downstream and experimental'''.

It will not be fully supported until mature support exists in the upstream Linux kernel and

the [https://github.com/u-boot/u-boot U-Boot] boot loader, but using an UEFI bootloader already provides a workable solution.

the [https://github.com/u-boot/u-boot U-Boot] boot loader, but using an '''UEFI bootloader already provides a workable solution'''.

The Raspberry Pi 5's boot process follows the [https://youtu.be/UvFG76qM6co?si=e9O1s9mS3wpIpEl9&t=308 typical boot stages on embedded devices],

The Raspberry Pi 5's boot process follows the [https://youtu.be/UvFG76qM6co?si=e9O1s9mS3wpIpEl9&t=308 typical boot stages on embedded devices], some of which have to be adapted to work with NixOS. For that it's helpful to understand more about the stages:

some of which have to be adapted to work with NixOS:

1. ROM boot loader: The first-stage boot loader comes "burned in" on the Pi in a tiny

1. '''ROM boot loader''': The first-stage boot loader comes "burned in" on the Pi in a tiny

[https://de.wikipedia.org/wiki/One_Time_Programmable One-Time-Programmable memory (OTP)]

so it cannot be changed anymore. It's only able to load the next second-stage boot loader below, and reset it in case you have messed up.

so it cannot be changed anymore. It's '''only able to load the next second-stage boot loader below''', and reset it in case you have messed up.

See the [https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#first-stage-bootloader official documentation].

Nothing to adapt here.

2. EEPROM boot loader: The second-stage boot loader comes built-in on the Pi in a bit larger, rewriteable

2. '''EEPROM boot loader''': The second-stage boot loader comes built-in on the Pi in a bit larger, rewriteable

[https://en.wikipedia.org/wiki/EEPROM EEPROM] memory

This loader is also very limited is only able to search for and start yet another, third-stage boot loader from other

'''This loader is also very limited is only able to search for and start yet another, third-stage boot loader from other

storage hardware like an SD card, an NVME SSD, an USB disk, or from the network.

storage hardware like an SD card, an NVME SSD''', an USB disk, or from the network.

This loader (as many other second-stage boot loaders of other devices) is so size-constraint that it only contains

the bare mimum code to be able to read from an FAT formatted partition. That's why you see and want a separate small

Line 67:

3. Firmware boot loader: The third-stage boot loader is loaded from the first partition (usually called <code>/boot</code>)

3. '''Firmware boot loader''': The third-stage boot loader is loaded from the first partition (usually called <code>/boot</code>)

of an SD card, NVME SSD or other storage hardware described above.

Because size is usually not an issue here anymore you can have large, fully-fledged boot loaders like

Because '''size is usually not an issue here anymore you can have large, fully-fledged boot loaders''' like

[https://www.freedesktop.org/software/systemd/man/latest/systemd-boot.html systemd-boot] (default with NixOS; requires UEFI), or full

[https://github.com/u-boot/u-boot U-Boot] (popular with embedded devices like the Pi) or

[https://www.gnu.org/software/grub/ GRUB] (generally popular with Linux Distros).

However, the standard Pi 5 setup has no third-stage boot loader.

However, '''the standard Pi 5 setup has no third-stage boot loader'''.

The second stage EEPROM boot loader loads the firmware (code to control other hardware on the Pi 5; [https://en.wikipedia.org/wiki/Devicetree device tree

files] in compact binary format <code>*.dtb</code>), some settings (<code>cmdline.txt</code> on which partition to find the rest of the system;

Line 85:

Line 86:

See the [https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#differences-on-raspberry-pi-5 official documentation].

Adaptions for NixOS:

'''Adaptions for booting NixOS''':

In order to boot NixOS with it's default boot loader systemd-boot we need UEFI support so replace the

{

In order to boot NixOS with it's default boot loader systemd-boot we need UEFI support, so replace the

1. ROM -> 2. EEPROM -> Kernel -> NixOS

}

workflow with third-stage and fourth-stage boot loaders (both as firmware on an SD card or NVME SSD etc.)

{

1. ROM -> 2. EEPROM -> 3. EDK2 (UEFI boot loader) -> 4. systemd-boot -> Kernel -> NixOS

}

as follows:

1. Install EDK2:

1. '''Install EDK2''':

We need the first partition of the SD card (or NVME SSD, etc.) again to be formatted as FAT

but labelled <code>ESP</code> (EFI System Partition) to conform to (U)EFI standards.

Line 106:

Line 105:

See a [https://github.com/NixOS/nixpkgs/issues/260754#issuecomment-1908664693 guide on how to setup partitions and these files].

2. Install systemd-boot, kernel and NixOS:

2. '''Install systemd-boot, kernel and NixOS''':

The rest is usual NixOS installation on a second partition with the caveat to select a Linux kernel that supports the Pi 5;

a suitable kernel can be created using [https://gitlab.com/vriska/nix-rpi5/-/blob/main/linux-rpi.nix leo60228's flake] until

Line 122:

Line 121:

Missing:

- How to do faster cross-compilation without binfmt.

- How to create a convenient SD card image to not install anything manually.

# How to do faster cross-compilation without binfmt.

- How to install U-Boot instead of EDK2 and systemd-boot.

# How to create a convenient SD card image to not install anything manually.

# How to install U-Boot instead of EDK2 and systemd-boot.

=== GPU ===

@@ Line 32: / Line 32: @@
-Support for the Raspberry Pi 5 is currently downstream and experimental.
+'''Support for the Raspberry Pi 5 is currently downstream and experimental'''.
 It will not be fully supported until mature support exists in the upstream Linux kernel and
-the [https://github.com/u-boot/u-boot U-Boot] boot loader, but using an UEFI bootloader already provides a workable solution.
+the [https://github.com/u-boot/u-boot U-Boot] boot loader, but using an '''UEFI bootloader already provides a workable solution'''.
-The Raspberry Pi 5's boot process follows the [https://youtu.be/UvFG76qM6co?si=e9O1s9mS3wpIpEl9&t=308 typical boot stages on embedded devices],
+The Raspberry Pi 5's boot process follows the [https://youtu.be/UvFG76qM6co?si=e9O1s9mS3wpIpEl9&t=308 typical boot stages on embedded devices], some of which have to be adapted to work with NixOS. For that it's helpful to understand more about the stages:
-some of which have to be adapted to work with NixOS:
-. ROM boot loader: The first-stage boot loader comes "burned in" on the Pi in a tiny
+. '''ROM boot loader''': The first-stage boot loader comes "burned in" on the Pi in a tiny
 [https://de.wikipedia.org/wiki/One_Time_Programmable One-Time-Programmable memory (OTP)]
-so it cannot be changed anymore. It's only able to load the next second-stage boot loader below, and reset it in case you have messed up.
+so it cannot be changed anymore. It's '''only able to load the next second-stage boot loader below''', and reset it in case you have messed up.
 See the [https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#first-stage-bootloader official documentation].
 Nothing to adapt here.
-. EEPROM boot loader: The second-stage boot loader comes built-in on the Pi in a bit larger, rewriteable
+. '''EEPROM boot loader''': The second-stage boot loader comes built-in on the Pi in a bit larger, rewriteable
 [https://en.wikipedia.org/wiki/EEPROM EEPROM] memory
-This loader is also very limited is only able to search for and start yet another, third-stage boot loader from other
+'''This loader is also very limited is only able to search for and start yet another, third-stage boot loader from other
-storage hardware like an SD card, an NVME SSD, an USB disk, or from the network.
+storage hardware like an SD card, an NVME SSD''', an USB disk, or from the network.
 This loader (as many other second-stage boot loaders of other devices) is so size-constraint that it only contains
 the bare mimum code to be able to read from an FAT formatted partition. That's why you see and want a separate small
@@ Line 67: / Line 67: @@
-. Firmware boot loader: The third-stage boot loader is loaded from the first partition (usually called <code>/boot</code>)
+. '''Firmware boot loader''': The third-stage boot loader is loaded from the first partition (usually called <code>/boot</code>)
 of an SD card, NVME SSD or other storage hardware described above.
-Because size is usually not an issue here anymore you can have large, fully-fledged boot loaders like
+Because '''size is usually not an issue here anymore you can have large, fully-fledged boot loaders''' like
 [https://www.freedesktop.org/software/systemd/man/latest/systemd-boot.html systemd-boot] (default with NixOS; requires UEFI), or full
 [https://github.com/u-boot/u-boot U-Boot] (popular with embedded devices like the Pi) or
 [https://www.gnu.org/software/grub/ GRUB] (generally popular with Linux Distros).
-However, the standard Pi 5 setup has no third-stage boot loader.
+However, '''the standard Pi 5 setup has no third-stage boot loader'''.
 The second stage EEPROM boot loader loads the firmware (code to control other hardware on the Pi 5; [https://en.wikipedia.org/wiki/Devicetree device tree
 files] in compact binary format <code>*.dtb</code>), some settings (<code>cmdline.txt</code> on which partition to find the rest of the system;
@@ Line 85: / Line 86: @@
 See the [https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#differences-on-raspberry-pi-5 official documentation].
-Adaptions for NixOS:
+'''Adaptions for booting NixOS''':
-In order to boot NixOS with it's default boot loader systemd-boot we need UEFI support so replace the
-{
+In order to boot NixOS with it's default boot loader systemd-boot we need UEFI support, so replace the
 . ROM -> 2. EEPROM -> Kernel -> NixOS
-}
 workflow with third-stage and fourth-stage boot loaders (both as firmware on an SD card or NVME SSD etc.)
-{
 . ROM -> 2. EEPROM -> 3. EDK2 (UEFI boot loader) -> 4. systemd-boot -> Kernel -> NixOS
-}
 as follows:
-. Install EDK2:
+. '''Install EDK2''':
 We need the first partition of the SD card (or NVME SSD, etc.) again to be formatted as FAT
 but labelled <code>ESP</code> (EFI System Partition) to conform to (U)EFI standards.
@@ Line 106: / Line 105: @@
 See a [https://github.com/NixOS/nixpkgs/issues/260754#issuecomment-1908664693 guide on how to setup partitions and these files].
-. Install systemd-boot, kernel and NixOS:
+. '''Install systemd-boot, kernel and NixOS''':
 The rest is usual NixOS installation on a second partition with the caveat to select a Linux kernel that supports the Pi 5;
 a suitable kernel can be created using [https://gitlab.com/vriska/nix-rpi5/-/blob/main/linux-rpi.nix leo60228's flake] until
@@ Line 122: / Line 121: @@
 Missing:
-- How to do faster cross-compilation without binfmt.
-- How to create a convenient SD card image to not install anything manually.
+# How to do faster cross-compilation without binfmt.
-- How to install U-Boot instead of EDK2 and systemd-boot.
+# How to create a convenient SD card image to not install anything manually.
+# How to install U-Boot instead of EDK2 and systemd-boot.
 === GPU ===