File List

Here is a list of all files with brief descriptions:

docs
kernel
kernel
arch
aarch64
cpu
fpsimd.c	Aarch64: the FP/SIMD registers, switched lazily, as x86's FPU is (see docs/kernel/processes.md)
init.c	Aarch64: setting up the kernel, from where boot/head.S jumps to, up to kmain(), in the order that docs/kernel/booting.md's table gives (as x86's x86_cpu_init() does)
libc.c	The functions that the compiler calls on its own, to copy a structure or zero a big array: memcpy, memset, memmove and memcmp
trace.c	Aarch64: a panic's stack trace, from the frame records (AAPCS64): x29 points to the caller's x29 and its return address
trap.c	Aarch64: turning exceptions into the kernel's events (see docs/kernel/interrupts.md)
earlycon
earlycon.c	Aarch64's early console: the PL011 UART, written to a character at a time by polling, until the terminals are up
include
boot
boot.h
core
arch.h
system.h
cpu
cpu.h
io.h
mm
mm.h
pmap.h
config.h
mm
pmap.c	Aarch64: the page tables, with 4 levels and 4 KiB pages
platform
virt
include
platform
virt.h
devices.c	The virt machine's devices that no bus finds (see dev/platform.h): where QEMU puts them (hw/arm/virt.c), as its devicetree also says
fdt.c	Reading the devicetree that the boot loader passes (a flattened one, an FDT) into the kernel's struct boot: the RAM (/memory's reg property), the initrd (/chosen's linux,initrd-start and linux,initrd-end), and the command line (/chosen's bootargs)
gic.c	The virt machine's interrupt controller: ARM's GICv2
init.c	QEMU's virt machine: setting up its interrupt controller and its PCI Express host bridge
irq.c	The interrupts' handlers on the virt machine, installed by their drivers (see dev/irq.h)
psci.c	Restarting and powering off the machine, by PSCI calls to the firmware (QEMU's), made with hvc, as the virt machine's devicetree says (/psci: method "hvc")
rtc.c	The date and time: the virt machine's PL031 real time clock, which counts seconds since the epoch
timer.c	The tick: the virtual timer of ARM's generic timer, which is each CPU's own (PPI 27)
sys
execve.c	Aarch64: where a new program starts, for execve()
fork.c	Aarch64: fork()'s child thread, which returns to user mode as its parent does, from a copy of its parent's saved registers at the top of its own kernel stack
proc.c	Aarch64: init, the first process: its thread, and where its program starts
sched.c	Aarch64: the timer tick, the idle loop, and the running thread giving up its CPU
signal.c	Aarch64: signals on the way back to user mode, and the signal handler's frame
smp.c	Aarch64 runs on one CPU only, so far
syscall.c	Aarch64: system calls
thread.c	Aarch64: making threads, starting them, switching to them, and ending them
i386
boot
init.c	I386: the kernel's first steps in C, moving itself to the higher half
cpu
arith.c	I386: 64-bit division, for the code GCC generates
cpu.h
fpu.c	X86: the FPU and SSE registers, switched lazily between threads
gdt.c	X86: the Global Descriptor Table (GDT) and the TSS
idt.c	X86: the Interrupt Descriptor Table (IDT), which says where each interrupt and exception vector goes
init.c	X86: setting up the boot CPU and memory, then on to the kernel
isr.c	X86: exceptions and system calls
smp.c	X86: starting the other CPUs, the application processors (APs)
trace.c	X86: a panic's stack trace
earlycon
earlycon.c	X86: the early console, where printk() writes before the kernel's terminals exist
fb.c	X86: the early console on the boot loader's framebuffer
font.h	8x16 font, the characters of code page 437 in order: generated by mkfont.py from unscii-16 by Viznut (public domain, https://viznut.fi/unscii/)
uart.c	X86: the early console on the first serial port (COM1, port 0x3F8), polled: each character waits until the UART can take it
vga.c	X86: the early console in VGA text mode, written straight into the text buffer at 0xB8000 (through the kernel's mapping of low memory, VMA(), which i386 and x86_64 both have)
include
boot
boot.h
multiboot.h	Multiboot.h - Multiboot header file
core
arch.h
panic.h
platform.h
system.h
cpu
cpu.h
io.h
msr.h
sdt.h
smp.h
mm
mm.h
pmap.h
platform
misc.h
config.h
mm
i386.c	I386: page tables, with 32-bit paging (two levels, 4 KiB pages)
i386.h
mm.c	X86: what the architecture adds to setting up memory at boot
tlb.c	X86: keeping the CPUs' TLBs up to date when a mapping changes
x86_64.c	X86_64: page tables, with 4-level paging
platform
misc
acpi.c	X86: ACPI's tables, and powering off
apic.c	X86: the APIC, the local APICs and the I/O APICs
cmos.c	X86: the PC's real time clock, in the CMOS: the date and time, which the kernel reads to set its clock at boot (arch_time_get())
hpet.c	X86: the High Precision Event Timer (HPET), as a clock
irq.c	X86: devices' interrupts (IRQs), whichever controller brings them: the 8259s or the APIC, each an x86_irq_chip
pic.c	X86: the PC's two 8259 programmable interrupt controllers (PICs)
pit.c	X86: the 8254 programmable interval timer (PIT)
pc
devices.c	The PC's devices that no bus finds (see dev/platform.h), at the ports and ISA interrupts that every PC has them on
init.c	The PC platform: its interrupt controllers, its timers, its PCI bus and its real time clock, set up at boot, and the tick
reboot.c	The PC: restarting, halting and powering off
sys
clock.c	X86: the clock, arch_rtime_ns(), the nanoseconds since it started
execve.c	X86: where a new program starts, for execve()
fork.c	X86: the child's thread, for fork()
proc.c	X86: the first process's thread
sched.c	X86: the scheduler's architecture side: the tick, the idle loop, and a thread that sleeps, yields or ends
signal.c	X86: signals, on the way back to user mode, and a handler's frame
sys.h
syscall.c	X86: system calls
thread.c	X86: a thread's CPU state, its kernel stack, and switching to it
core
kargs.c	The kernel's command line: the arguments the boot loader passed, such as root=/dev/hda2 or apic=off
main.c	The kernel's generic entry point, kmain()
module.c	The built-in modules: the drivers and filesystems that are part of the kernel
printk.c	printk(): the kernel's messages
snprintf.c	snprintf() and vsnprintf(): formatting into a buffer, with the formats printk() has: c, s, d and u (32-bit), ld and lu (64-bit), x and lx (hexadecimal), b (binary) and p
ssp.c	What the compiler's stack protector (-fstack-protector) needs: the canary value it puts on the stack, and the function it calls when a function returns with that value overwritten
time.c	The wall clock: the date and time of day
dev
ata
ata.c	The ATA driver: hard disks on the IDE controller, as block device 3 (/dev/hda and up)
ata.h
dma.c	ATA bus master DMA, for IDE controllers that can (such as QEMU's PIIX)
pio.c	ATA programmed I/O (PIO): the CPU moves the data itself
fb
fbdev
fbdev.c	The framebuffer devices: /dev/fb0 and up (character device 29, as on Linux)
vesa
vesa.c	The VESA framebuffer: the linear framebuffer that the boot loader set up, as /dev/fb0
input
i8042.c	The driver for the i8042, the PC's keyboard controller
kbd
ps2kbd.c	The PS/2 keyboard driver
mem
kmsg.c	/dev/kmsg (character device 1, 11): the kernel's messages
memdev.c	The memory devices: the character devices of major 1, as on Linux
memdev.h
null.c	/dev/null (character device 1, 3): reading it gives nothing, the end of the file at once, and what is written to it is thrown away
random.c	Random numbers: /dev/random and /dev/urandom (character devices 1, 8 and 1, 9), which are the same, and random_get() for the kernel
zero.c	/dev/zero (character device 1, 5): reading it gives as many zero bytes as asked for, and what is written to it is thrown away
mouse
ps2mouse.c	The PS/2 mouse driver: /dev/mouse (character device 10, 1)
net
e1000.c	The driver for Intel's 8254x (e1000) and 82574L Ethernet controllers
pci
conf1.c	PCI configuration space through configuration mechanism #1, the PC's
ecam.c	PCI configuration space through ECAM, the Enhanced Configuration Access Mechanism of PCI Express
pci.c	The PCI bus: finding devices, and reading and writing their configuration space
rd
ramdisk.c	The RAM disk: the initial RAM disk the boot loader loaded, as block device 1, 0
tty
pty
pty.c	Pseudo-terminals: /dev/ptmx and /dev/pts/N
uart
8250
8250.c	The driver for the 8250 UART and its successors, such as the 16550 with its FIFOs: the PC's serial ports, /dev/ttyS0 and up
pl011
pl011.c	The driver for ARM's PrimeCell UART (PL011), the serial port of QEMU's virt machine: /dev/ttyS0, and /dev/console when there are no virtual terminals
uart.c	Serial ports as terminals: /dev/ttyS0 and up (character device 4, 64 and up)
vt
fb.c	Virtual terminals on the framebuffer
keyboard.c	The keyboard of the virtual terminals
term.c	The terminal emulator of the virtual terminals
vga.c	Virtual terminals in VGA text mode, when there is no framebuffer
vt.c	Virtual terminals: /dev/tty1 to /dev/tty6 (character device 4, 1 to 6), and /dev/console, which is the first one
generic.c	The terminal layer: the line discipline, and job control
tty.c	The terminal devices' numbers: which driver each one is
blkcache.c	The block cache: what the disks read and write, kept in 4 KiB blocks
kdev.c	The device layer: devices by their numbers, and what calls them
platform.c	The platform's devices: those that no bus can find (see dev/platform.h)
fs
devfs
devfs.c	Devfs: the filesystem of device nodes, usually mounted on /dev
devpts
devpts.c	Devpts: the filesystem of the pseudo-terminals' slave devices, usually mounted on /dev/pts
ext2
block.c	Ext2: reading and writing the disk, the block group descriptors, and allocating and freeing blocks in the groups' block bitmaps
dentry.c	Ext2: directory entries
ext2.c	Ext2: loading and mounting the filesystem, and the vnodes of its inodes
ext2.h
inode.c	Ext2: inodes, and the blocks of a file
remove.c	Ext2: removing, linking and renaming entries, and freeing what a file used
super.c	Ext2: writing the superblock back to the disk
vops.c	Ext2: the vnode operations: reading and writing files, directories, making nodes, truncating, and attributes
initramfs
cpio
cpio.c	Cpiofs: the RAM disk as a filesystem, read straight from an archive in the old binary cpio format
cpio.h
initramfs.c	Initramfs: the root filesystem from the RAM disk the boot loader loaded
minix
block.c	Minix: allocating and freeing data blocks (zones), and reading and writing them, through the block cache for the ones read often
dentry.c	Minix: directory entries, a name and an inode number each, in the directory's blocks
inode.c	Minix: inodes, and the zones of a file
minix.c	Minix: loading and mounting the filesystem, and the vnodes of its inodes
minix.h
super.c	Minix: writing the superblock back to the disk
vops.c	Minix: the vnode operations: reading and writing files, directories, making nodes, and truncating
posix
close.c	The generic close operation for files that are vnodes
helpers.c	Generic answers, for regular files, to whether a read is at the end of the file
ioctl.c	The generic ioctl operation for files that are vnodes
lseek.c	The generic lseek operation for files that are vnodes, as POSIX (IEEE Std 1003.1) describes it
open.c	The generic open operation for files that are vnodes
read.c	The generic read operation for files that are vnodes: regular files, and devices, pipes and FIFOs, which may have to wait for data
readdir.c	The generic readdir operation for directories that are vnodes
trunc.c	The generic truncate operation for files that are vnodes
write.c	The generic write operation for files that are vnodes: regular files, and devices, pipes and FIFOs, which may have to wait for room
procfs
procfs.c	Procfs: the kernel's and the processes' state as files, usually mounted on /proc
pseudofs
pseudofs.c	Pseudofs: the directories of the filesystems that live in memory (tmpfs, and so devfs and devpts)
tmpfs
tmpfs.c	Tmpfs: a filesystem in memory, gone when the system stops
attr.c	Changing a vnode's attributes: its mode (chmod()), its owner (chown()) and its times (utimensat())
bcache.c	The block cache: a filesystem's blocks kept in memory, by a number the filesystem chooses (minix uses the block number), so that a block read again and again is read once
close.c	Closing a vnode: dropping a reference to it
file.c	Open files (struct file, in fs/vfs.h): what open(), pipe(), socket() and accept() make, and what descriptors refer to
flock.c	Advisory locks on whole files, for flock()
fops.c	The operations on open files: each goes to the socket layer, the device's driver, or the vnode's filesystem (its fops)
iobuf.c	Iobufs: moving bytes into and out of the buffer of a read or a write, which may be in user memory (see fs/iobuf.h)
ioctl.c	ioctl() on a vnode: passed on to its device or its filesystem
link.c	Links by path: hard links (link()), symbolic links (symlink(), readlink()), and renaming (rename())
lookup.c	Path lookup: walking a path one component at a time, from vnode to vnode
mknod.c	Making a filesystem node by its path: a file, a directory, a device node, a FIFO or a symbolic link
mount.c	Mounting: a filesystem on a directory, by type (mount()), and the root filesystem from a disk partition
pipe.c	Pipes, and FIFOs: a ring buffer in memory, written at one end and read at the other
read.c	Reading from a vnode: from its device, or through its filesystem
readdir.c	Reading a directory's entries, and finding one by name
rofs.c	The operations of a read-only filesystem that would change it: each fails with EROFS
stat.c	stat(): a vnode's attributes, in the structure user space gets
sync.c	Syncing vnodes and filesystems to their disks
trunc.c	Truncating a vnode: changing a file's length
unlink.c	Removing a name by its path: unlink() and rmdir()
vcache.c	The vnode cache: a filesystem's vnodes that are in use, by inode number, so that a file opened twice gets the same vnode
vfs.c	The virtual filesystem (VFS): the filesystems that are installed, the root, mounting one filesystem on a directory of another, and permissions
vm_object.c	The page cache: a file's pages in memory, for mmap()
vops.c	The vnode operations that work on a directory and a name, or on a vnode's inode: each checks its arguments, then calls the filesystem's operation (vops)
write.c	Writing to a vnode: to its device, or through its filesystem
include
boot
boot.h
console
earlycon.h
core
arch.h
assert.h
kargs.h
module.h
panic.h
printk.h
qsort.h
string.h
system.h
time.h
types.h
cpu
cpu.h
io.h
dev
blkcache.h
dev.h
fbdev.h
i8042.h
irq.h
kbd.h
pci.h
platform.h
ramdev.h
random.h
tty.h
ttydev.h
uart.h
vt.h
ds
bitmap.h
buddy.h
hashmap.h
list.h
queue.h
ringbuf.h
fs
bcache.h
devfs.h
devpts.h
initramfs.h
iobuf.h
mbr.h
pipe.h
posix.h
pseudofs.h
rofs.h
stat.h
tmpfs.h
vcache.h
vfs.h
mm
buddy.h
kvmem.h
mm.h
pmap.h
vm.h
vmem.h
net
byteorder.h
inet.h
netbuf.h
netif.h
socket.h
tcp.h
sys
binfmt.h
callout.h
cpu.h
elf.h
kthread.h
lock.h
proc.h
reboot.h
sched.h
signal.h
syscall.h
thread.h
uaccess.h
waitq.h
video
vbe.h
vesa.h
config.h
stdarg.h
stddef.h
stdint.h
mm
buddy.c	The buddy allocator: physical memory, in blocks of 2^n pages
fault.c	Page faults: a process's page brought in when it first touches it
kvmem.c	kmalloc() and kfree(): the kernel's memory for its own structures
mm.c	Physical memory: setting it up at boot, and the pages of it
slab.c	Slabs: the kernel's small objects
vm_anon.c	Anons: the pages a process has written to, in one of its mappings
vm_entry.c	Map entries: the mappings of an address space
vm_object.c	Vm objects: what a mapping's pages come from, such as a file
vm_space.c	Address spaces: a process's mappings (map entries), kept in address order, and its page tables (pmap)
vmem.c	Vmem, an allocator of ranges of addresses (see mm/vmem.h)
vmm.c	Mapping and unmapping a map entry's range in an address space, and the kernel's own address space (kvm_space)
net
inet
arp.c	ARP: finding the hardware (MAC) address of an IPv4 address on the link
ether.c	Ethernet, and the Internet checksum
icmp.c	ICMP
ifioctl.c	The network interfaces' ioctl() requests, made on an AF_INET socket
ipv4.c	IPv4
socket.c	AF_INET datagram sockets: UDP (SOCK_DGRAM), and ping sockets (SOCK_DGRAM with IPPROTO_ICMP), which send echo requests and receive the replies, without needing root
tcp_input.c	TCP input (RFC 9293 3.10.7, "SEGMENT ARRIVES")
tcp_output.c	TCP output
tcp_socket.c	TCP connections (struct tcp_pcb) and their sockets (SOCK_STREAM)
udp.c	UDP input
unix
unix.c	Unix domain sockets (AF_UNIX): stream sockets between processes of this machine, named by a path in the file system
unix.h
netbuf.c	Packet buffers (see net/netbuf.h)
netif.c	Network interfaces (see net/netif.h)
socket.c	Sockets: what every domain's sockets share
sys
binfmt
binfmt.c	Loading a program into a process, for execve()
elf.c	The ELF loader
callout.c	Callouts: functions to call at a time to come (see sys/callout.h)
execve.c	execve(): a process runs another program
fork.c	fork(): a copy of the calling process
kthread.c	Kernel threads
lock.c	The kernel lock
proc.c	Processes: making them and ending them, their IDs, their descriptors, and their sessions and process groups
reboot.c	Restarting, halting and powering off the machine (reboot()), and Ctrl+Alt+Del
sched.c	The scheduler: which thread runs next, and the tick
signal.c	Signals: sending them, and taking them on the way back to user mode
sys_file.c	System calls on files: opening, reading and writing them, their names and attributes, directories, links, mounts and locks
sys_net.c	System calls on sockets: making them, binding, listening, accepting and connecting, sending and receiving, their names and options
sys_poll.c	System calls that wait for any of several descriptors: select() (and pselect()) and poll()
sys_proc.c	System calls about processes and threads: exit(), execve(), fork(), waitpid(), threads, IDs, process groups and sessions, memory (sbrk(), mmap(), munmap()), and the machine (uname(), reboot(), sethostname())
sys_signal.c	System calls about signals, timers and the time: kill(), sigaction(), the signal mask, sigsuspend() and sigreturn(), setitimer(), nanosleep(), and the clocks
syscall.c	System calls: what the architecture calls when user mode makes one (syscall_dispatch()), the table of them, and the helpers that several kinds of calls share, for the user memory and descriptors they take
syscalls.h
thread.c	Threads: making one in a process, and ending one
waitq.c	Wait queues (see sys/waitq.h)