What hardware NULLos talks to today – and what's coming.
| What | How |
|---|
| Screen | UEFI GOP framebuffer: nb asks for it, the kernel draws text into it with its own
line font (sharp at any size, with real lowercase letters). Shows UTF-8: all of Latin-1 with umlauts, „quotation marks“, dashes – —, €, arrows and box lines. Understands the most important ANSI control sequences. |
| Keyboard | PS/2 via interrupt (IRQ 1) – or over USB if the computer has no PS/2 controller (like Macs and new PCs). German layout with umlauts, AltGr and Caps Lock, delivers UTF-8. Switch: kb load us, Mac keyboards: kb load de-mac. |
| Serial port | 16550 on COM1, 115200 baud, via interrupt (IRQ 4). Runs alongside the
screen – that's how QEMU talks to the terminal and the boot test talks to NULLos. |
| CPUs | All cores from the ACPI table (up to 16), started via INIT/SIPI, each with its own timer. |
| Interrupts | Local APIC + IOAPIC, found via ACPI (MADT). The old PIC is off. |
| Time | APIC timer at 100 Hz, calibrated against the HPET (otherwise PIT); fine time from the TSC;
clock time from the CMOS clock. |
| Disks | SATA via AHCI, NVMe SSDs, USB sticks and virtio-blk – all become sda, sdb … with partitions (GPT, MBR or none). Programs can only read them so far; the kernel can already write to NVMe. Writing from programs is coming soon |
| USB | xHCI controller, hubs (up to 5 levels), keyboard, mouse, sticks (Bulk-Only + SCSI), USB Ethernet (CDC-ECM/NCM). Plugging in and unplugging while running works. Protection against BadUSB: At startup only the first pure keyboard is allowed, every new device waits without a driver until you allow it. |
| File system | FAT12, FAT16 and FAT32 with long names, read only: the boot partition under /boot, more via mount from a disk or image file.
Plus the RAM file system /. |
| Network cards | virtio-net (legacy and virtio 1.x), Intel e1000e and igb (82576), USB Ethernet and Intel e1000 (82540EM, 82545EM, 82574L). net at the kernel prompt shows addresses and counters. |
| TCP/IP | Its own stack, IPv6 and IPv4 on equal terms: neighbor discovery, SLAAC, DNS from the router advertisement,
DHCPv6, ARP, DHCPv4, ping replies, UDP, TCP. Plus Unix sockets. |
| Devices | /dev with numbers like Linux: null zero random urandom tty console, the disk as sda with partitions sda1 …; device list with all PCI functions. |
| Randomness | RDSEED/RDRAND of the CPU, virtio-rng (legacy and 1.x), interrupt timings → ChaCha20 generator. |
| Reboot / Off | Via ACPI with its own AML interpreter: “off” really powers down, power button, battery and lid are detected (in QEMU with test tables). Sleep: coming soon |
| Sound | /dev/snd via virtio-sound and Intel HDA, checked bit-exact in QEMU. |
| Mouse, tablet, touchpad | USB HID with wheel and extra buttons, absolute pointers, touchpad with several fingers – all as events in /dev/eingabe. |
Tested in QEMU (machine q35): TCP with 1 MB there and back over IPv4 and IPv6, and two NULLos talking to each other over a link. DHCPv6 is still untested (QEMU has no server for it). USB and NVMe are checked with QEMU's emulated devices. Real PCs: not yet. coming soon