The Crimson API is organized around a small number of kernel subsystems. Use this page as the human index, then jump to the generated file and member references for exact signatures.

Kernel And Boot

Use rad_kernel_init(), rad_kernel_poll(), rad_kernel_run(), rad_kernel_shutdown(), rad_printk(), rad_cpu_idle(), and the rad_boot_info_t helpers to bring a platform online and report early state.

Time, Tasks, And Synchronization

Use rad_time_micros(), timer-source registration, rad_task_create_config(), wait queues, mutexes, and events for in-kernel scheduling and coordination. rad_scheduler_info_get() and rad_core_info_get() expose current scheduling and multicore state.

POSIX-Inspired Runtime

Use VFS handles for kernel code and integer file descriptors for the userspace path. rad_syscall_dispatch() is the stable syscall dispatch table boundary for the current x86 VM work.

Device Model

Use rad_device_register() for generic device nodes and subsystem wrappers for specialized devices: block, network, framebuffer, input, TTY, PTY, audio, serial, and USB. Ioctl request macros follow a Linux-style direction/type/number/size layout. The first USB surface is host-info discovery for /dev/usb0, with HID devices expected to publish input events through the generic input queues.

Networking

The experimental network path registers /dev/net0 on the x86 VM when virtio-net is present, supports Ethernet frame send/receive operations, and provides small IPv4/UDP datagram and local TCP stream socket subsets through the POSIX-inspired syscall table. Full wire-level TCP/IP remains future work.

Driver Binding

Modules advertise name, bus, and compatibility metadata. I2C and SPI controllers register a bus, child drivers match overlay children by compatible, and DMA controllers provide channels for peripherals such as SPI TX/RX.

Overlay Tree And IRQs

Use the overlay APIs to load runtime tree blobs, query properties, and bind devices. IRQ domains convert tree-local interrupts cells into flat RADPx-OS IRQ resources that drivers can enable, disable, and attach handlers to.

Display And Input

Framebuffers describe memory layout, output type, connector, available modes, and primary display state. Input queues provide a shared event path for keyboard, pointer, terminal, Slint, shell, and future GUI consumers.

Experimental Compositor

RADCompositor is the current Slint-backed windowing service. It renders desktop and application surfaces into off-screen buffers, tracks dirty rectangles, composes damaged regions into a software back buffer, presents only dirty framebuffer rectangles, and translates global pointer events into per-surface Slint input events. The x86 smoke path also accepts a shm-backed userspace surface through /dev/compositor0.