xv6-riscv API Documentation

API map

├── Small Unix-like kernel
│   ├── Processes and scheduler
│   ├── Context switching
│   ├── Virtual memory
│   ├── Traps and interrupts
│   ├── System-call dispatcher
│   ├── File descriptors
│   ├── Pipes
│   ├── File system and log
│   ├── Locks
│   ├── Device drivers
│   └── String and memory
├── Small user-space C library
│   ├── String and memory
│   │   ├── strlen()
│   │   ├── strcpy()
│   │   ├── strcmp()
│   │   ├── memset()
│   │   ├── memmove()
│   │   ├── memcpy()
│   │   └── memcmp()
│   ├── Input and output
│   │   ├── printf()
│   │   ├── fprintf()
│   │   └── gets()
│   ├── Memory allocation
│   │   ├── malloc()
│   │   ├── free()
│   │   ├── sbrk()
│   │   └── sbrklazy()
│   └── Utilities
│       ├── atoi()
│       ├── stat()
│       └── strchr()
├── 21 Unix-like system calls
│   ├── Process
│   │   ├── fork()
│   │   ├── exit()
│   │   ├── wait()
│   │   ├── kill()
│   │   ├── exec()
│   │   └── getpid()
│   ├── Memory and time
│   │   ├── sbrk()
│   │   ├── pause()
│   │   └── uptime()
│   ├── File descriptors
│   │   ├── pipe()
│   │   ├── read()
│   │   ├── fstat()
│   │   ├── dup()
│   │   ├── write()
│   │   └── close()
│   └── File system
│       ├── chdir()
│       ├── open()
│       ├── mknod()
│       ├── unlink()
│       ├── link()
│       └── mkdir()
├── Small Unix user environment
│   └── Commands and tests
│       ├── init
│       ├── sh
│       ├── cat
│       ├── echo
│       ├── grep
│       ├── ls
│       ├── wc
│       ├── mkdir
│       ├── rm
│       ├── ln
│       └── test programs
└── Header guide
    ├── Function declarations
    │   ├── kernel/defs.h
    │   └── user/user.h
    ├── Inline functions
    │   └── kernel/riscv.h
    ├── Types and structs
    │   ├── kernel/types.h
    │   ├── kernel/proc.h
    │   ├── kernel/file.h
    │   ├── kernel/fs.h
    │   ├── kernel/buf.h
    │   ├── kernel/spinlock.h
    │   ├── kernel/sleeplock.h
    │   ├── kernel/elf.h
    │   ├── kernel/virtio.h
    │   └── kernel/vm.h
    ├── Constants and macros
    │   ├── kernel/param.h
    │   ├── kernel/memlayout.h
    │   ├── kernel/syscall.h
    │   └── kernel/fcntl.h
    └── ABI shared with user space
        └── kernel/stat.h

Header guide

Header Kind Provides Symbols

kernel/defs.h Functions Kernel internal function declarations. binit(), bread(), brelse(), bwrite(), bpin(), bunpin(), consoleinit(), consoleintr(), consputc(), kexec(), filealloc(), fileclose(), filedup(), fileinit(), fileread(), filestat(), filewrite(), fsinit(), dirlink(), dirlookup(), ialloc(), idup(), iinit(), ilock(), iput(), iunlock(), iunlockput(), iupdate(), namecmp(), namei(), nameiparent(), readi(), stati(), writei(), itrunc(), ireclaim(), kalloc(), kfree(), kinit(), initlog(), log_write(), begin_op(), end_op(), pipealloc(), pipeclose(), piperead(), pipewrite(), printf(), panic(), printfinit(), cpuid(), kexit(), kfork(), growproc(), proc_mapstacks(), proc_pagetable(), proc_freepagetable(), kkill(), killed(), setkilled(), mycpu(), myproc(), procinit(), scheduler(), sched(), sleep(), userinit(), kwait(), wakeup(), yield(), either_copyout(), either_copyin(), procdump(), swtch(), acquire(), holding(), initlock(), release(), push_off(), pop_off(), acquiresleep(), releasesleep(), holdingsleep(), initsleeplock(), memcmp(), memmove(), memset(), safestrcpy(), strlen(), strncmp(), strncpy(), argint(), argstr(), argaddr(), fetchstr(), fetchaddr(), syscall(), trapinit(), trapinithart(), prepare_return(), uartinit(), uartintr(), uartwrite(), uartputc_sync(), uartgetc(), kvminit(), kvminithart(), kvmmap(), mappages(), uvmcreate(), uvmalloc(), uvmdealloc(), uvmcopy(), uvmfree(), uvmunmap(), uvmclear(), walk(), walkaddr(), copyout(), copyin(), copyinstr(), ismapped(), vmfault(), plicinit(), plicinithart(), plic_claim(), plic_complete(), virtio_disk_init(), virtio_disk_rw(), virtio_disk_intr(), NELEM

user/user.h Functions User syscall and small C library declarations. SBRK_ERROR, fork(), exit(), wait(), pipe(), write(), read(), close(), kill(), exec(), open(), mknod(), unlink(), fstat(), link(), mkdir(), chdir(), dup(), getpid(), sys_sbrk(), pause(), uptime(), stat(), strcpy(), strchr(), strcmp(), gets(), strlen(), memset(), atoi(), memcmp(), sbrk(), sbrklazy(), fprintf(), printf(), malloc(), free()

kernel/riscv.h Inline functions + constants CSR helpers, page-table constants, PTE helpers, and interrupt-control primitives. r_mhartid(), MSTATUS_MPP_MASK, MSTATUS_MPP_M, MSTATUS_MPP_S, MSTATUS_MPP_U, r_mstatus(), w_mstatus(), w_mepc(), SSTATUS_SPP, SSTATUS_SPIE, SSTATUS_UPIE, SSTATUS_SIE, SSTATUS_UIE, r_sstatus(), w_sstatus(), r_sip(), w_sip(), SIE_SEIE, SIE_STIE, r_sie(), w_sie(), MIE_STIE, r_mie(), w_mie(), w_sepc(), r_sepc(), r_medeleg(), w_medeleg(), r_mideleg(), w_mideleg(), w_stvec(), r_stvec(), r_stimecmp(), w_stimecmp(), r_menvcfg(), w_menvcfg(), w_pmpcfg0(), w_pmpaddr0(), SATP_SV39, MAKE_SATP, w_satp(), r_satp(), r_scause(), r_stval(), w_mcounteren(), r_mcounteren(), r_time(), intr_on(), intr_off(), intr_get(), r_sp(), r_tp(), w_tp(), r_ra(), sfence_vma(), PGSIZE, PGSHIFT, PGROUNDUP, PGROUNDDOWN, PTE_V, PTE_R, PTE_W, PTE_X, PTE_U, PA2PTE, PTE2PA, PTE_FLAGS, PXMASK, PXSHIFT, PX, MAXVA

kernel/types.h Types Fixed-width integer aliases. ushort, uchar, pde_t

kernel/proc.h Types CPU, context, trapframe, process state, and process structures. context, cpu, trapframe, procstate, proc

kernel/file.h Types + macros Open file, inode, device-switch, and device-number helpers. file, major, minor, mkdev, inode, devsw, CONSOLE

kernel/fs.h Types + constants On-disk file-system layout, inode format, and directory entry format. ROOTINO, BSIZE, superblock, FSMAGIC, NDIRECT, NINDIRECT, MAXFILE, dinode, IPB, IBLOCK, BPB, BBLOCK, DIRSIZ, dirent

kernel/buf.h Types Buffer-cache block structure. buf

kernel/spinlock.h Types Spinlock structure. spinlock

kernel/sleeplock.h Types Sleeplock structure. sleeplock

kernel/stat.h ABI types + constants File type constants and the stat structure. T_DIR, T_FILE, T_DEVICE, stat

kernel/elf.h Types + constants ELF header and program-header structures. ELF_MAGIC, elfhdr, proghdr, ELF_PROG_LOAD, ELF_PROG_FLAG_EXEC, ELF_PROG_FLAG_WRITE, ELF_PROG_FLAG_READ

kernel/virtio.h Types + constants VirtIO MMIO, queue, and block-device constants and structures. VIRTIO_MMIO_MAGIC_VALUE, VIRTIO_MMIO_VERSION, VIRTIO_MMIO_DEVICE_ID, VIRTIO_MMIO_VENDOR_ID, VIRTIO_MMIO_DEVICE_FEATURES, VIRTIO_MMIO_DRIVER_FEATURES, VIRTIO_MMIO_QUEUE_SEL, VIRTIO_MMIO_QUEUE_NUM_MAX, VIRTIO_MMIO_QUEUE_NUM, VIRTIO_MMIO_QUEUE_READY, VIRTIO_MMIO_QUEUE_NOTIFY, VIRTIO_MMIO_INTERRUPT_STATUS, VIRTIO_MMIO_INTERRUPT_ACK, VIRTIO_MMIO_STATUS, VIRTIO_MMIO_QUEUE_DESC_LOW, VIRTIO_MMIO_QUEUE_DESC_HIGH, VIRTIO_MMIO_DRIVER_DESC_LOW, VIRTIO_MMIO_DRIVER_DESC_HIGH, VIRTIO_MMIO_DEVICE_DESC_LOW, VIRTIO_MMIO_DEVICE_DESC_HIGH, VIRTIO_CONFIG_S_ACKNOWLEDGE, VIRTIO_CONFIG_S_DRIVER, VIRTIO_CONFIG_S_DRIVER_OK, VIRTIO_CONFIG_S_FEATURES_OK, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_CONFIG_WCE, VIRTIO_BLK_F_MQ, VIRTIO_F_ANY_LAYOUT, VIRTIO_RING_F_INDIRECT_DESC, VIRTIO_RING_F_EVENT_IDX, NUM, virtq_desc, VRING_DESC_F_NEXT, VRING_DESC_F_WRITE, virtq_avail, virtq_used_elem, virtq_used, VIRTIO_BLK_T_IN, VIRTIO_BLK_T_OUT, virtio_blk_req

kernel/param.h Constants Compile-time xv6 limits. NPROC, NCPU, NOFILE, NFILE, NINODE, NDEV, ROOTDEV, MAXARG, MAXOPBLOCKS, LOGBLOCKS, NBUF, FSSIZE, MAXPATH, USERSTACK

kernel/memlayout.h Constants + macros Physical and virtual address layout. UART0, UART0_IRQ, VIRTIO0, VIRTIO0_IRQ, PLIC, PLIC_PRIORITY, PLIC_PENDING, PLIC_SENABLE, PLIC_SPRIORITY, PLIC_SCLAIM, KERNBASE, PHYSTOP, TRAMPOLINE, KSTACK, TRAPFRAME

kernel/syscall.h Constants System-call numbers. SYS_fork, SYS_exit, SYS_wait, SYS_pipe, SYS_read, SYS_kill, SYS_exec, SYS_fstat, SYS_chdir, SYS_dup, SYS_getpid, SYS_sbrk, SYS_pause, SYS_uptime, SYS_open, SYS_write, SYS_mknod, SYS_unlink, SYS_link, SYS_mkdir, SYS_close

kernel/vm.h Types + constants Page-table type aliases and page-size constants. SBRK_EAGER, SBRK_LAZY

kernel/fcntl.h Constants Open flag constants. O_RDONLY, O_WRONLY, O_RDWR, O_CREATE, O_TRUNC

Header	Kind	Provides	Symbols
kernel/defs.h	Functions	Kernel internal function declarations.	`binit()`, `bread()`, `brelse()`, `bwrite()`, `bpin()`, `bunpin()`, `consoleinit()`, `consoleintr()`, `consputc()`, `kexec()`, `filealloc()`, `fileclose()`, `filedup()`, `fileinit()`, `fileread()`, `filestat()`, `filewrite()`, `fsinit()`, `dirlink()`, `dirlookup()`, `ialloc()`, `idup()`, `iinit()`, `ilock()`, `iput()`, `iunlock()`, `iunlockput()`, `iupdate()`, `namecmp()`, `namei()`, `nameiparent()`, `readi()`, `stati()`, `writei()`, `itrunc()`, `ireclaim()`, `kalloc()`, `kfree()`, `kinit()`, `initlog()`, `log_write()`, `begin_op()`, `end_op()`, `pipealloc()`, `pipeclose()`, `piperead()`, `pipewrite()`, `printf()`, `panic()`, `printfinit()`, `cpuid()`, `kexit()`, `kfork()`, `growproc()`, `proc_mapstacks()`, `proc_pagetable()`, `proc_freepagetable()`, `kkill()`, `killed()`, `setkilled()`, `mycpu()`, `myproc()`, `procinit()`, `scheduler()`, `sched()`, `sleep()`, `userinit()`, `kwait()`, `wakeup()`, `yield()`, `either_copyout()`, `either_copyin()`, `procdump()`, `swtch()`, `acquire()`, `holding()`, `initlock()`, `release()`, `push_off()`, `pop_off()`, `acquiresleep()`, `releasesleep()`, `holdingsleep()`, `initsleeplock()`, `memcmp()`, `memmove()`, `memset()`, `safestrcpy()`, `strlen()`, `strncmp()`, `strncpy()`, `argint()`, `argstr()`, `argaddr()`, `fetchstr()`, `fetchaddr()`, `syscall()`, `trapinit()`, `trapinithart()`, `prepare_return()`, `uartinit()`, `uartintr()`, `uartwrite()`, `uartputc_sync()`, `uartgetc()`, `kvminit()`, `kvminithart()`, `kvmmap()`, `mappages()`, `uvmcreate()`, `uvmalloc()`, `uvmdealloc()`, `uvmcopy()`, `uvmfree()`, `uvmunmap()`, `uvmclear()`, `walk()`, `walkaddr()`, `copyout()`, `copyin()`, `copyinstr()`, `ismapped()`, `vmfault()`, `plicinit()`, `plicinithart()`, `plic_claim()`, `plic_complete()`, `virtio_disk_init()`, `virtio_disk_rw()`, `virtio_disk_intr()`, `NELEM`
user/user.h	Functions	User syscall and small C library declarations.	`SBRK_ERROR`, `fork()`, `exit()`, `wait()`, `pipe()`, `write()`, `read()`, `close()`, `kill()`, `exec()`, `open()`, `mknod()`, `unlink()`, `fstat()`, `link()`, `mkdir()`, `chdir()`, `dup()`, `getpid()`, `sys_sbrk()`, `pause()`, `uptime()`, `stat()`, `strcpy()`, `strchr()`, `strcmp()`, `gets()`, `strlen()`, `memset()`, `atoi()`, `memcmp()`, `sbrk()`, `sbrklazy()`, `fprintf()`, `printf()`, `malloc()`, `free()`
kernel/riscv.h	Inline functions + constants	CSR helpers, page-table constants, PTE helpers, and interrupt-control primitives.	`r_mhartid()`, `MSTATUS_MPP_MASK`, `MSTATUS_MPP_M`, `MSTATUS_MPP_S`, `MSTATUS_MPP_U`, `r_mstatus()`, `w_mstatus()`, `w_mepc()`, `SSTATUS_SPP`, `SSTATUS_SPIE`, `SSTATUS_UPIE`, `SSTATUS_SIE`, `SSTATUS_UIE`, `r_sstatus()`, `w_sstatus()`, `r_sip()`, `w_sip()`, `SIE_SEIE`, `SIE_STIE`, `r_sie()`, `w_sie()`, `MIE_STIE`, `r_mie()`, `w_mie()`, `w_sepc()`, `r_sepc()`, `r_medeleg()`, `w_medeleg()`, `r_mideleg()`, `w_mideleg()`, `w_stvec()`, `r_stvec()`, `r_stimecmp()`, `w_stimecmp()`, `r_menvcfg()`, `w_menvcfg()`, `w_pmpcfg0()`, `w_pmpaddr0()`, `SATP_SV39`, `MAKE_SATP`, `w_satp()`, `r_satp()`, `r_scause()`, `r_stval()`, `w_mcounteren()`, `r_mcounteren()`, `r_time()`, `intr_on()`, `intr_off()`, `intr_get()`, `r_sp()`, `r_tp()`, `w_tp()`, `r_ra()`, `sfence_vma()`, `PGSIZE`, `PGSHIFT`, `PGROUNDUP`, `PGROUNDDOWN`, `PTE_V`, `PTE_R`, `PTE_W`, `PTE_X`, `PTE_U`, `PA2PTE`, `PTE2PA`, `PTE_FLAGS`, `PXMASK`, `PXSHIFT`, `PX`, `MAXVA`
kernel/types.h	Types	Fixed-width integer aliases.	`ushort`, `uchar`, `pde_t`
kernel/proc.h	Types	CPU, context, trapframe, process state, and process structures.	`context`, `cpu`, `trapframe`, `procstate`, `proc`
kernel/file.h	Types + macros	Open file, inode, device-switch, and device-number helpers.	`file`, `major`, `minor`, `mkdev`, `inode`, `devsw`, `CONSOLE`
kernel/fs.h	Types + constants	On-disk file-system layout, inode format, and directory entry format.	`ROOTINO`, `BSIZE`, `superblock`, `FSMAGIC`, `NDIRECT`, `NINDIRECT`, `MAXFILE`, `dinode`, `IPB`, `IBLOCK`, `BPB`, `BBLOCK`, `DIRSIZ`, `dirent`
kernel/buf.h	Types	Buffer-cache block structure.	`buf`
kernel/spinlock.h	Types	Spinlock structure.	`spinlock`
kernel/sleeplock.h	Types	Sleeplock structure.	`sleeplock`
kernel/stat.h	ABI types + constants	File type constants and the stat structure.	`T_DIR`, `T_FILE`, `T_DEVICE`, `stat`
kernel/elf.h	Types + constants	ELF header and program-header structures.	`ELF_MAGIC`, `elfhdr`, `proghdr`, `ELF_PROG_LOAD`, `ELF_PROG_FLAG_EXEC`, `ELF_PROG_FLAG_WRITE`, `ELF_PROG_FLAG_READ`
kernel/virtio.h	Types + constants	VirtIO MMIO, queue, and block-device constants and structures.	`VIRTIO_MMIO_MAGIC_VALUE`, `VIRTIO_MMIO_VERSION`, `VIRTIO_MMIO_DEVICE_ID`, `VIRTIO_MMIO_VENDOR_ID`, `VIRTIO_MMIO_DEVICE_FEATURES`, `VIRTIO_MMIO_DRIVER_FEATURES`, `VIRTIO_MMIO_QUEUE_SEL`, `VIRTIO_MMIO_QUEUE_NUM_MAX`, `VIRTIO_MMIO_QUEUE_NUM`, `VIRTIO_MMIO_QUEUE_READY`, `VIRTIO_MMIO_QUEUE_NOTIFY`, `VIRTIO_MMIO_INTERRUPT_STATUS`, `VIRTIO_MMIO_INTERRUPT_ACK`, `VIRTIO_MMIO_STATUS`, `VIRTIO_MMIO_QUEUE_DESC_LOW`, `VIRTIO_MMIO_QUEUE_DESC_HIGH`, `VIRTIO_MMIO_DRIVER_DESC_LOW`, `VIRTIO_MMIO_DRIVER_DESC_HIGH`, `VIRTIO_MMIO_DEVICE_DESC_LOW`, `VIRTIO_MMIO_DEVICE_DESC_HIGH`, `VIRTIO_CONFIG_S_ACKNOWLEDGE`, `VIRTIO_CONFIG_S_DRIVER`, `VIRTIO_CONFIG_S_DRIVER_OK`, `VIRTIO_CONFIG_S_FEATURES_OK`, `VIRTIO_BLK_F_RO`, `VIRTIO_BLK_F_SCSI`, `VIRTIO_BLK_F_CONFIG_WCE`, `VIRTIO_BLK_F_MQ`, `VIRTIO_F_ANY_LAYOUT`, `VIRTIO_RING_F_INDIRECT_DESC`, `VIRTIO_RING_F_EVENT_IDX`, `NUM`, `virtq_desc`, `VRING_DESC_F_NEXT`, `VRING_DESC_F_WRITE`, `virtq_avail`, `virtq_used_elem`, `virtq_used`, `VIRTIO_BLK_T_IN`, `VIRTIO_BLK_T_OUT`, `virtio_blk_req`
kernel/param.h	Constants	Compile-time xv6 limits.	`NPROC`, `NCPU`, `NOFILE`, `NFILE`, `NINODE`, `NDEV`, `ROOTDEV`, `MAXARG`, `MAXOPBLOCKS`, `LOGBLOCKS`, `NBUF`, `FSSIZE`, `MAXPATH`, `USERSTACK`
kernel/memlayout.h	Constants + macros	Physical and virtual address layout.	`UART0`, `UART0_IRQ`, `VIRTIO0`, `VIRTIO0_IRQ`, `PLIC`, `PLIC_PRIORITY`, `PLIC_PENDING`, `PLIC_SENABLE`, `PLIC_SPRIORITY`, `PLIC_SCLAIM`, `KERNBASE`, `PHYSTOP`, `TRAMPOLINE`, `KSTACK`, `TRAPFRAME`
kernel/syscall.h	Constants	System-call numbers.	`SYS_fork`, `SYS_exit`, `SYS_wait`, `SYS_pipe`, `SYS_read`, `SYS_kill`, `SYS_exec`, `SYS_fstat`, `SYS_chdir`, `SYS_dup`, `SYS_getpid`, `SYS_sbrk`, `SYS_pause`, `SYS_uptime`, `SYS_open`, `SYS_write`, `SYS_mknod`, `SYS_unlink`, `SYS_link`, `SYS_mkdir`, `SYS_close`
kernel/vm.h	Types + constants	Page-table type aliases and page-size constants.	`SBRK_EAGER`, `SBRK_LAZY`
kernel/fcntl.h	Constants	Open flag constants.	`O_RDONLY`, `O_WRONLY`, `O_RDWR`, `O_CREATE`, `O_TRUNC`

Small Unix-like Kernel

Generated from kernel/defs.h; each entry links to the implementation when one exists in the checked-in source.

Processes and scheduler

Declaration	Header	Description
`int kexec(char, char*);`	kernel/defs.h:26	Replace the current process image with an ELF program.
`int cpuid(void);`	kernel/defs.h:81	Return the current hart's CPU index.
`void kexit(int);`	kernel/defs.h:82	Terminate the current process and wake its parent.
`int kfork(void);`	kernel/defs.h:83	Create a child process by copying the current process.
`int growproc(int);`	kernel/defs.h:84	Grow or shrink the current process address space.
`void proc_mapstacks(pagetable_t);`	kernel/defs.h:85	Map fixed kernel stacks for every process slot.
`pagetable_t proc_pagetable(struct proc *);`	kernel/defs.h:86	Create a user page table with trampoline mappings.
`void proc_freepagetable(pagetable_t, uint64);`	kernel/defs.h:87	Free a process page table and its user pages.
`int kkill(int);`	kernel/defs.h:88	Mark a process so it exits when it next reaches user mode.
`int killed(struct proc*);`	kernel/defs.h:89	Report whether a process has been marked for termination.
`void setkilled(struct proc*);`	kernel/defs.h:90	Set a process's killed flag.
`struct cpu* mycpu(void);`	kernel/defs.h:91	Return the current CPU structure.
`struct proc* myproc();`	kernel/defs.h:92	Return the process running on the current CPU.
`void procinit(void);`	kernel/defs.h:93	Initialize process table locks and kernel stacks.
`void scheduler(void) __attribute__((noreturn));`	kernel/defs.h:94	Run the per-CPU process scheduling loop.
`void sched(void);`	kernel/defs.h:95	Switch from the current process to the scheduler.
`void sleep(void, struct spinlock);`	kernel/defs.h:96	Atomically sleep on a channel while releasing a lock.
`void userinit(void);`	kernel/defs.h:97	Create the first user process.
`int kwait(uint64);`	kernel/defs.h:98	Wait for a child process to exit and collect its status.
`void wakeup(void*);`	kernel/defs.h:99	Wake processes sleeping on a channel.
`void yield(void);`	kernel/defs.h:100	Give up the CPU and become runnable again.
`int either_copyout(int user_dst, uint64 dst, void *src, uint64 len);`	kernel/defs.h:101	Copy to either user memory or kernel memory.
`int either_copyin(void *dst, int user_src, uint64 src, uint64 len);`	kernel/defs.h:102	Copy from either user memory or kernel memory.
`void procdump(void);`	kernel/defs.h:103	Print a process table snapshot for debugging.

Context switching

Declaration	Header	Description
`void swtch(struct context, struct context);`	kernel/defs.h:106	Save one kernel context and restore another.

Virtual memory

Declaration	Header	Description
`void* kalloc(void);`	kernel/defs.h:59	Allocate and return one zeroed physical page.
`void kfree(void *);`	kernel/defs.h:60	Return one physical page to the allocator freelist.
`void kinit(void);`	kernel/defs.h:61	Initialize the physical page allocator.
`void kvminit(void);`	kernel/defs.h:154	Build the kernel page table.
`void kvminithart(void);`	kernel/defs.h:155	Install the kernel page table on the current hart.
`void kvmmap(pagetable_t, uint64, uint64, uint64, int);`	kernel/defs.h:156	Map a physical range into the kernel page table.
`int mappages(pagetable_t, uint64, uint64, uint64, int);`	kernel/defs.h:157	Install page-table entries for a virtual address range.
`pagetable_t uvmcreate(void);`	kernel/defs.h:158	Allocate an empty user page table.
`uint64 uvmalloc(pagetable_t, uint64, uint64, int);`	kernel/defs.h:159	Grow a user address space and allocate pages.
`uint64 uvmdealloc(pagetable_t, uint64, uint64);`	kernel/defs.h:160	Shrink a user address space.
`int uvmcopy(pagetable_t, pagetable_t, uint64);`	kernel/defs.h:161	Copy a parent address space into a child page table.
`void uvmfree(pagetable_t, uint64);`	kernel/defs.h:162	Free a user page table and all mapped pages.
`void uvmunmap(pagetable_t, uint64, uint64, int);`	kernel/defs.h:163	Remove user page-table mappings and optionally free pages.
`void uvmclear(pagetable_t, uint64);`	kernel/defs.h:164	Clear user access on one page-table entry.
`pte_t * walk(pagetable_t, uint64, int);`	kernel/defs.h:165	Find or allocate a page-table entry for a virtual address.
`uint64 walkaddr(pagetable_t, uint64);`	kernel/defs.h:166	Translate a user virtual address to a physical address.
`int copyout(pagetable_t, uint64, char *, uint64);`	kernel/defs.h:167	Copy bytes from kernel memory into a user virtual address.
`int copyin(pagetable_t, char *, uint64, uint64);`	kernel/defs.h:168	Copy bytes from a user virtual address into kernel memory.
`int copyinstr(pagetable_t, char *, uint64, uint64);`	kernel/defs.h:169	Copy a null-terminated user string into kernel memory.
`int ismapped(pagetable_t, uint64);`	kernel/defs.h:170	Report whether a user virtual address has a valid PTE.
`uint64 vmfault(pagetable_t, uint64, int);`	kernel/defs.h:171	Handle a lazy-allocation page fault.

Traps and interrupts

Declaration	Header	Description
`void trapinit(void);`	kernel/defs.h:141	Initialize global trap handling state.
`void trapinithart(void);`	kernel/defs.h:142	Install the kernel trap vector on the current hart.
`void prepare_return(void);`	kernel/defs.h:144	Prepare trapframe and registers for return to user mode.

System-call dispatcher

Declaration	Header	Description
`void argint(int, int*);`	kernel/defs.h:132	Read an integer syscall argument from the current trapframe.
`int argstr(int, char*, int);`	kernel/defs.h:133	Copy a string syscall argument from user memory.
`void argaddr(int, uint64 *);`	kernel/defs.h:134	Read a pointer-sized syscall argument from the current trapframe.
`int fetchstr(uint64, char*, int);`	kernel/defs.h:135	Fetch a null-terminated string from user memory.
`int fetchaddr(uint64, uint64*);`	kernel/defs.h:136	Fetch a 64-bit value from the current process's user memory.
`void syscall();`	kernel/defs.h:137	Dispatch the current process's syscall number.

File descriptors

Declaration	Header	Description
`struct file* filealloc(void);`	kernel/defs.h:29	Allocate an unused entry from the global open-file table.
`void fileclose(struct file*);`	kernel/defs.h:30	Close a file object and release its underlying resource.
`struct file* filedup(struct file*);`	kernel/defs.h:31	Increase a file object's reference count.
`void fileinit(void);`	kernel/defs.h:32	Initialize the global open-file table lock.
`int fileread(struct file*, uint64, int n);`	kernel/defs.h:33	Read through a file, pipe, or device descriptor.
`int filestat(struct file*, uint64 addr);`	kernel/defs.h:34	Copy file metadata into a user stat structure.
`int filewrite(struct file*, uint64, int n);`	kernel/defs.h:35	Write through a file, pipe, or device descriptor.

Pipes

Declaration	Header	Description
`int pipealloc(struct file, struct file);`	kernel/defs.h:70	Create paired read and write file objects for a pipe.
`void pipeclose(struct pipe*, int);`	kernel/defs.h:71	Close one side of a pipe and wake blocked peers.
`int piperead(struct pipe*, uint64, int);`	kernel/defs.h:72	Read bytes from a pipe into user memory.
`int pipewrite(struct pipe*, uint64, int);`	kernel/defs.h:73	Write bytes from user memory into a pipe.

File system and log

Declaration	Header	Description
`void binit(void);`	kernel/defs.h:13	Initialize the buffer cache and its block list.
`struct buf* bread(uint, uint);`	kernel/defs.h:14	Return a locked buffer containing a disk block.
`void brelse(struct buf*);`	kernel/defs.h:15	Release a locked buffer and move it toward the MRU end.
`void bwrite(struct buf*);`	kernel/defs.h:16	Write a locked buffer back to disk.
`void bpin(struct buf*);`	kernel/defs.h:17	Prevent a cached disk block from being evicted.
`void bunpin(struct buf*);`	kernel/defs.h:18	Drop a buffer-cache pin reference.
`void fsinit(int);`	kernel/defs.h:38	Initialize file-system state from the disk superblock.
`int dirlink(struct inode, char, uint);`	kernel/defs.h:39	Add a directory entry that points to an inode number.
`struct inode* dirlookup(struct inode, char, uint*);`	kernel/defs.h:40	Find a named entry inside a directory inode.
`struct inode* ialloc(uint, short);`	kernel/defs.h:41	Allocate a fresh on-disk inode of a given type.
`struct inode* idup(struct inode*);`	kernel/defs.h:42	Increment an inode reference count.
`void iinit();`	kernel/defs.h:43	Initialize the in-memory inode cache.
`void ilock(struct inode*);`	kernel/defs.h:44	Lock an inode and load its on-disk metadata if needed.
`void iput(struct inode*);`	kernel/defs.h:45	Drop an inode reference and free it when links disappear.
`void iunlock(struct inode*);`	kernel/defs.h:46	Release a locked inode.
`void iunlockput(struct inode*);`	kernel/defs.h:47	Unlock an inode and drop one reference.
`void iupdate(struct inode*);`	kernel/defs.h:48	Write an inode's in-memory metadata to disk.
`int namecmp(const char, const char);`	kernel/defs.h:49	Compare xv6 directory entry names.
`struct inode* namei(char*);`	kernel/defs.h:50	Resolve a pathname to an inode.
`struct inode* nameiparent(char, char);`	kernel/defs.h:51	Resolve a pathname to its parent directory inode.
`int readi(struct inode*, int, uint64, uint, uint);`	kernel/defs.h:52	Read bytes from an inode into kernel or user memory.
`void stati(struct inode, struct stat);`	kernel/defs.h:53	Fill a stat structure from an inode.
`int writei(struct inode*, int, uint64, uint, uint);`	kernel/defs.h:54	Write bytes from kernel or user memory into an inode.
`void itrunc(struct inode*);`	kernel/defs.h:55	Free all data blocks owned by an inode.
`void ireclaim(int);`	kernel/defs.h:56	Clear inode-cache entries for a removed device.
`void initlog(int, struct superblock*);`	kernel/defs.h:64	Initialize the write-ahead log from the file-system superblock.
`void log_write(struct buf*);`	kernel/defs.h:65	Record that a buffer must be written during log commit.
`void begin_op(void);`	kernel/defs.h:66	Start a logged file-system operation, waiting if the log is full.
`void end_op(void);`	kernel/defs.h:67	Finish a logged file-system operation and commit if needed.

Locks

Declaration	Header	Description
`void acquire(struct spinlock*);`	kernel/defs.h:109	Take a spinlock and disable interrupt-driven preemption.
`int holding(struct spinlock*);`	kernel/defs.h:110	Report whether the current CPU holds a spinlock.
`void initlock(struct spinlock, char);`	kernel/defs.h:111	Initialize a spinlock with a debug name.
`void release(struct spinlock*);`	kernel/defs.h:112	Release a spinlock and restore interrupt state.
`void push_off(void);`	kernel/defs.h:113	Disable interrupts and record nested critical-section depth.
`void pop_off(void);`	kernel/defs.h:114	Restore interrupt enable state after a critical section.
`void acquiresleep(struct sleeplock*);`	kernel/defs.h:117	Take a sleeplock, sleeping until the lock becomes available.
`void releasesleep(struct sleeplock*);`	kernel/defs.h:118	Release a sleeplock and wake waiters.
`int holdingsleep(struct sleeplock*);`	kernel/defs.h:119	Report whether the current process holds a sleeplock.
`void initsleeplock(struct sleeplock, char);`	kernel/defs.h:120	Initialize a sleeplock with a debug name.

Device drivers

Declaration	Header	Description
`void consoleinit(void);`	kernel/defs.h:21	Initialize console input, console output, and UART interrupts.
`void consoleintr(int);`	kernel/defs.h:22	Handle one console input character from the UART driver.
`void consputc(int);`	kernel/defs.h:23	Write one character to the console device.
`int printf(char*, ...) __attribute__ ((format (printf, 1, 2)));`	kernel/defs.h:76	Format text to the kernel console.
`void panic(char*) __attribute__((noreturn));`	kernel/defs.h:77	Print a panic message and stop the kernel.
`void printfinit(void);`	kernel/defs.h:78	Initialize the console print lock.
`void uartinit(void);`	kernel/defs.h:147	Initialize the UART hardware.
`void uartintr(void);`	kernel/defs.h:148	Handle UART receive and transmit interrupts.
`void uartwrite(char [], int);`	kernel/defs.h:149	Write a buffer to the UART console.
`void uartputc_sync(int);`	kernel/defs.h:150	Synchronously write one character to the UART.
`int uartgetc(void);`	kernel/defs.h:151	Read one received UART character if available.
`void plicinit(void);`	kernel/defs.h:174	Configure global PLIC interrupt priorities.
`void plicinithart(void);`	kernel/defs.h:175	Enable PLIC delivery for the current hart.
`int plic_claim(void);`	kernel/defs.h:176	Claim the next pending external interrupt.
`void plic_complete(int);`	kernel/defs.h:177	Tell the PLIC an interrupt has been handled.
`void virtio_disk_init(void);`	kernel/defs.h:180	Initialize the VirtIO block device and descriptor ring.
`void virtio_disk_rw(struct buf *, int);`	kernel/defs.h:181	Submit a synchronous block read or write request.
`void virtio_disk_intr(void);`	kernel/defs.h:182	Handle completed VirtIO disk requests.

String and memory

Declaration	Header	Description
`int memcmp(const void, const void, uint);`	kernel/defs.h:123	Compare two byte ranges.
`void* memmove(void, const void, uint);`	kernel/defs.h:124	Copy bytes between overlapping memory ranges.
`void* memset(void*, int, uint);`	kernel/defs.h:125	Fill a memory range with one byte value.
`char* safestrcpy(char, const char, int);`	kernel/defs.h:126	Copy a string while always terminating the destination.
`int strlen(const char*);`	kernel/defs.h:127	Return the length of a null-terminated string.
`int strncmp(const char, const char, uint);`	kernel/defs.h:128	Compare bounded strings.
`char* strncpy(char, const char, int);`	kernel/defs.h:129	Copy a bounded string.

Small User-space C Library

Generated from the non-syscall declarations in user/user.h.

String and memory

Declaration	Header	Description
`char* strcpy(char, const char);`	user/user.h:30	Copy a null-terminated string.
`void memmove(void, const void*, int);`	user/user.h:31	Copy bytes between possibly overlapping memory ranges.
`int strcmp(const char, const char);`	user/user.h:33	Compare two null-terminated strings.
`uint strlen(const char*);`	user/user.h:35	Return the length of a null-terminated string.
`void* memset(void*, int, uint);`	user/user.h:36	Fill a memory range with one byte value.
`int memcmp(const void , const void , uint);`	user/user.h:38	Compare two byte ranges.
`void memcpy(void , const void *, uint);`	user/user.h:39	Copy bytes between non-overlapping memory ranges.

Input and output

Declaration	Header	Description
`char* gets(char*, int max);`	user/user.h:34	Read a line from standard input into a buffer.
`void fprintf(int, const char*, ...) __attribute__ ((format (printf, 2, 3)));`	user/user.h:44	Write formatted output to a file descriptor.
`void printf(const char*, ...) __attribute__ ((format (printf, 1, 2)));`	user/user.h:45	Write formatted output to standard output.

Memory allocation

Declaration	Header	Description
`char* sbrk(int);`	user/user.h:40	Grow the user heap through the normal syscall wrapper.
`char* sbrklazy(int);`	user/user.h:41	Grow the user heap using xv6's lazy-allocation mode.
`void* malloc(uint);`	user/user.h:48	Allocate bytes from the user heap.
`void free(void*);`	user/user.h:49	Return a malloc allocation to the user heap.

Utilities

Declaration	Header	Description
`int stat(const char, struct stat);`	user/user.h:29	Open a path and return its file metadata.
`char* strchr(const char*, char c);`	user/user.h:32	Find the first occurrence of a character in a string.
`int atoi(const char*);`	user/user.h:37	Parse a decimal string as an integer.

21 Unix-like System Calls

Generated from the dispatch table in kernel/syscall.c.

Process

Declaration	Header	Description
`int fork(void);`	user/user.h:6	Create a child process by copying the caller.
`int exit(int) __attribute__((noreturn));`	user/user.h:7	Terminate the current process with a status value.
`int wait(int*);`	user/user.h:8	Wait for a child process to exit.
`int kill(int);`	user/user.h:13	Request termination of a process by PID.
`int exec(const char, char*);`	user/user.h:14	Load and run a new program in the current process.
`int getpid(void);`	user/user.h:23	Return the current process ID.

Memory and time

Declaration	Header	Description
`char* sys_sbrk(int,int);`	user/user.h:24	Grow or shrink the process heap.
`int pause(int);`	user/user.h:25	Suspend the process for a short timer interval.
`int uptime(void);`	user/user.h:26	Return the number of timer ticks since boot.

File descriptors

Declaration	Header	Description
`int pipe(int*);`	user/user.h:9	Create a unidirectional pipe and return two descriptors.
`int read(int, void*, int);`	user/user.h:11	Read bytes from a file descriptor.
`int fstat(int fd, struct stat*);`	user/user.h:18	Return metadata for an open file descriptor.
`int dup(int);`	user/user.h:22	Duplicate an open file descriptor.
`int write(int, const void*, int);`	user/user.h:10	Write bytes to a file descriptor.
`int close(int);`	user/user.h:12	Release an open file descriptor.

File system

Declaration	Header	Description
`int chdir(const char*);`	user/user.h:21	Change the current process's working directory.
`int open(const char*, int);`	user/user.h:15	Open or create a file and return a descriptor.
`int mknod(const char*, short, short);`	user/user.h:16	Create a device inode.
`int unlink(const char*);`	user/user.h:17	Remove a directory entry.
`int link(const char, const char);`	user/user.h:19	Create a hard link to an existing inode.
`int mkdir(const char*);`	user/user.h:20	Create a directory at a pathname.

Small Unix User Environment

User commands and test programs in user/.

Command	Entry point	Description
`cat`	user/cat.c	Copy files or standard input to standard output.
`dorphan`	user/dorphan.c	User-space xv6 test or utility program.
`echo`	user/echo.c	Print command arguments.
`forktest tests`	user/forktest.c	User-space xv6 test or utility program.
`forphan`	user/forphan.c	User-space xv6 test or utility program.
`grep`	user/grep.c	Search input lines with a small regular-expression matcher.
`grind`	user/grind.c	User-space xv6 test or utility program.
`init`	user/init.c	First user process; starts the shell and reaps orphaned children.
`kill`	user/kill.c	User-space xv6 test or utility program.
`ln`	user/ln.c	Create a hard link.
`logstress`	user/logstress.c	User-space xv6 test or utility program.
`ls`	user/ls.c	List directory entries and file metadata.
`mkdir`	user/mkdir.c	Create a directory.
`rm`	user/rm.c	Remove a file or directory entry.
`sh`	user/sh.c	Small command shell with redirection, pipes, lists, and background jobs.
`stressfs`	user/stressfs.c	User-space xv6 test or utility program.
`usertests tests`	user/usertests.c	User-space xv6 test or utility program.
`wc`	user/wc.c	Count lines, words, and bytes.
`zombie`	user/zombie.c	User-space xv6 test or utility program.