LanternOS

About

LanternOS is a hobbyist 64-bit multitasking kernel that currently supports the Raspberry Pi 3 and Raspberry Pi 4 devices.

Building

Disclaimer: This has never been tested on real hardware. Run this on real hardware at your own risk. It is highly recommended to use an emulator such as QEMU.

Build requirements:

• Latest Rust Nightly
• Make
• Cargo Binutils (cargo install cargo-binutils)
• qemu-system-aarch64, if you do not have access to real hardware

Note that you will also need a file named card.img in the out/ directory that contains a FAT filesystem. This can be created for example with dd and mformat.

Once the build requirements are met, building the project should be as simple as running make. This will produce an out directory, containing the resulting binaries. These can be installed onto an SD Card and used in a real Raspberry Pi, or you can use qemu. To use qemu, run:

make qemu-raspi3

to run on a RPI3 VM. Qemu does not officially support the RPI4, but patches to provide support exist. If you build qemu yourself with these patches, you can run this project in a RPI3 VM via:

make qemu QEMU_PATH=<path-to-qemu>.

Roadmap

• Multi-stage bootloader to load kernel ELF into memory
• Initialize MMU and load kernel into higher half address space
• Implement synchronization primitives (Mutex, Barrier)
• Initialize secondary cores
• Implement statically-sized kernel heap and enable alloc crate
• Simple Read and write to FAT filesystem on SDCard
• Implement HAL to allow for easier porting across architectures other than ARM
• Automate building of card.img for use in qemu
• Define Syscall infrastructure
• Load userspace applications into lower half
• Create init userspace process (probably a shell)
• Basic Process scheduling
• Framebuffer driver
• Font rendering
• Graphical TTY to replace UART as primary output
• Dynamic linking support
• Research a bare minimum port of libc and possibly rust's std
• But can it run Doom?

Licensing Information

The kernel and bootloader are licensed under the MIT License.

Please see license.html for a full list of licensing information, including third-party licenses.

Sample Output

What follows is an example output of the kernel log via UART, which is currently the primary method of interfacing with the OS at this time:

[0.09980] Raspi bootloader is preparing environment for kernel...
[0.10450] Successfully parsed kernel ELF
[0.10524] Loaded Kernel ELF into memory
[0.10543] Initializing page frame allocator...
[3.46555] Successfully initialized page frame allocator with 1015650 free frames.
[3.46689] Mapped kernel to higher half range 0xffff000000000000 - 0xffff000000026000
[3.46743] Mapped four kernel stacks of size 0x2000 bytes
[3.46767] Mapped physical memory into higher half starting at address: 0xffff000040000000
[3.46790] Printing memory map:

Page size:       4.000 KiB
Reserved Pages:  32932
Available Pages: 1015644
Total Memory:    4.000 GiB
Avail Memory:    3.874 GiB

Type: Firmware   | 0x0000000000000000 - 0x0000000000001000 | 4.000 KiB
Type: Stack      | 0x0000000000001000 - 0x0000000000009000 | 32.000 KiB
Type: Kernel     | 0x0000000000009000 - 0x000000000002f000 | 152.000 KiB
Type: Free       | 0x000000000002f000 - 0x000000000007f000 | 320.000 KiB
Type: Bootloader | 0x000000000007f000 - 0x00000000000ce000 | 316.000 KiB
Type: Free       | 0x00000000000ce000 - 0x0000000008000000 | 127.195 MiB
Type: DeviceTree | 0x0000000008000000 - 0x0000000008020000 | 128.000 KiB
Type: Free       | 0x0000000008020000 - 0x000000003c000000 | 831.875 MiB
Type: Firmware   | 0x000000003c000000 - 0x0000000040000000 | 64.000 MiB
Type: Free       | 0x0000000040000000 - 0x00000000fbffa000 | 2.937 GiB
Type: BLReserved | 0x00000000fbffa000 - 0x00000000fc000000 | 24.000 KiB
Type: MMIO       | 0x00000000fc000000 - 0x0000000100000000 | 64.000 MiB

[3.47222] Bootloader allocated 6 pages of memory in total
[3.47264] Successfully enabled the MMU
[3.47304] Initializng secondary cores and transferring control to kernel entry point...

[3.47420] Performing kernel early init...
[3.47533] Registered exception handlers at 0xffff00000000b800
[4.07924] Initialized page frame allocator with 1015723 free frames
[4.08208] Initialized kernel heap at address range 0xffff000000032000 - 0xffff000000232000
[4.08587] Initialized EMMC2 driver. Storage medium ready to receive block requests.
[4.09861] Successfully read FAT filesystem from SDCard
[4.09895] Kernel initialization complete
[4.09916] Writing 'Hello, world!' to file 'hello.txt' at root dir
[4.10560] Waiting 5 seconds...
[9.10592] Opening file 'hello.txt' and reading file contents
[9.10836] Read 13 bytes from file. File contents: Hello, world!
[9.10908 | Core 3] Hello from secondary core!
[9.10941 | Core 2] Hello from secondary core!
[9.10950 | Core 1] Hello from secondary core!

KERNEL PANIC!
Location: libs/arch/raspi/exception/src/lib.rs:73:5
Reason:
Uncaught exception! Dumping CPU State:

Exception Syndrome: 0x96000004
Faulting Address: 0xdeadbeef
Saved Program Status: 0x200001c5
Exception Link Register: 0xffff0000000048a8
Link Register: 0xffff000000004890
Stack Pointer: 0xffff000000028430

General Purpose Registers:
X00: 0x0000000000000000  X01: 0x00000000000f4240
X02: 0x0000000000000001  X03: 0xffff00000000af58
X04: 0x0000000000000000  X05: 0x0000000000000002
X06: 0x000009eecbfb11e4  X07: 0x0000400000000000
X08: 0x00000000deadbeef  X09: 0xffff000000025af8
X10: 0x0000000000000000  X11: 0x0000000000000000
X12: 0x000000000000000a  X13: 0x0000000000000090
X14: 0xffff00000001f77a  X15: 0xffff000000024cf8
X16: 0xffff000000024df8  X17: 0x0000000000000005
X18: 0x0000000000000021  X19: 0xffff000000028b68
X20: 0xffff000000028af0  X21: 0xffff000000028b80
X22: 0xffff00000001f9a8  X23: 0xffff000000025a68
X24: 0xffff000000025a58  X25: 0x0000000000000000
X26: 0xffff000000231000  X27: 0x00000000fbdf9000
X28: 0xffff000000232000  X29: 0xffff000000025a88
X30: 0xffff000000004890

Q00: 0x000000000000f424  Q01: 0x0000000000000000
Q02: 0x0000000000000000  Q03: 0x0000000000000000
Q04: 0x0000000000000000  Q05: 0x0000000000000000
Q06: 0x0000000000000000  Q07: 0x0000000000000000
Q08: 0x0000000000000000  Q09: 0x0000000000000000
Q10: 0x0000000000000000  Q11: 0x0000000000000000
Q12: 0x0000000000000000  Q13: 0x0000000000000000
Q14: 0x0000000000000000  Q15: 0x0000000000000000
Q16: 0x0000000000000000  Q17: 0x0000000000000000
Q18: 0x0000000000000000  Q19: 0x0000000000000000
Q20: 0x0000000000000000  Q21: 0x0000000000000000
Q22: 0x0000000000000000  Q23: 0x0000000000000000
Q24: 0x0000000000000000  Q25: 0x0000000000000000
Q26: 0x0000000000000000  Q27: 0x0000000000000000
Q28: 0x0000000000000000  Q29: 0x0000000000000000
Q30: 0x0000000000000000  Q31: 0x0000000000000000