linux 내장 원본 코드의main 함수 분석
27380 단어 Linux 커널
：
main ， ， bootloader main C ， linux main 。linux ， main。 bootloader main？ main ？
， ：
1、main C ， ； ， ！ ， ， "main" ； ， linux C start_kernel（）； C 。 main ， ， 。
2、 main ！ main （ main ）； ， ， ！ main ！！ ， main ，main ！ linux main。 。
3、linux Windows。Windows （ ）， 。linux 。 bin ， 。
/*
* linux/init/main.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* GK 2/5/95 - Changed to support mounting root fs via NFS
* Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
* Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
* Simplified starting of init: Michael A. Griffith
* start_kernel->rest_init->kernel_init init pid=1
->kthreadd pid=x
->pid=0， idle
rest_init ， kernel_init ， init , ，
idle
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#ifdef CONFIG_X86_LOCAL_APIC
#include
#endif
static int kernel_init(void *);
extern void init_IRQ(void);
extern void fork_init(unsigned long);
extern void mca_init(void);
extern void sbus_init(void);
extern void prio_tree_init(void);
extern void radix_tree_init(void);
#ifndef CONFIG_DEBUG_RODATA
static inline void mark_rodata_ro(void) { }
#endif
#ifdef CONFIG_TC
extern void tc_init(void);
#endif
/*
* Debug helper: via this flag we know that we are in 'early bootup code'
* where only the boot processor is running with IRQ disabled. This means
* two things - IRQ must not be enabled before the flag is cleared and some
* operations which are not allowed with IRQ disabled are allowed while the
* flag is set.
*/
bool early_boot_irqs_disabled __read_mostly;
enum system_states system_state __read_mostly;
EXPORT_SYMBOL(system_state);
/*
* Boot command-line arguments
*/
#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
extern void time_init(void);
/* Default late time init is NULL. archs can override this later. */
void (*__initdata late_time_init)(void);
extern void softirq_init(void);
/* Untouched command line saved by arch-specific code. */
char __initdata boot_command_line[COMMAND_LINE_SIZE];
/* Untouched saved command line (eg. for /proc) */
char *saved_command_line;
/* Command line for parameter parsing */
static char *static_command_line;
static char *execute_command;
static char *ramdisk_execute_command;
/*
* If set, this is an indication to the drivers that reset the underlying
* device before going ahead with the initialization otherwise driver might
* rely on the BIOS and skip the reset operation.
*
* This is useful if kernel is booting in an unreliable environment.
* For ex. kdump situaiton where previous kernel has crashed, BIOS has been
* skipped and devices will be in unknown state.
*/
unsigned int reset_devices;
EXPORT_SYMBOL(reset_devices);
static int __init set_reset_devices(char *str)
{
reset_devices = 1;
return 1;
}
__setup("reset_devices", set_reset_devices);
static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
static const char *panic_later, *panic_param;
extern const struct obs_kernel_param __setup_start[], __setup_end[];
static int __init obsolete_checksetup(char *line)
{
const struct obs_kernel_param *p;
int had_early_param = 0;
p = __setup_start;
do {
int n = strlen(p->str);
if (parameqn(line, p->str, n)) {
if (p->early) {
/* Already done in parse_early_param?
* (Needs exact match on param part).
* Keep iterating, as we can have early
* params and __setups of same names 8( */
if (line[n] == '\0' || line[n] == '=')
had_early_param = 1;
} else if (!p->setup_func) {
printk(KERN_WARNING "Parameter %s is obsolete,"
" ignored
", p->str);
return 1;
} else if (p->setup_func(line + n))
return 1;
}
p++;
} while (p < __setup_end);
return had_early_param;
}
/*
* This should be approx 2 Bo*oMips to start (note initial shift), and will
* still work even if initially too large, it will just take slightly longer
*/
unsigned long loops_per_jiffy = (1<<12);
EXPORT_SYMBOL(loops_per_jiffy);
static int __init debug_kernel(char *str)
{
console_loglevel = 10;
return 0;
}
static int __init quiet_kernel(char *str)
{
console_loglevel = 4;
return 0;
}
early_param("debug", debug_kernel);
early_param("quiet", quiet_kernel);
static int __init loglevel(char *str)
{
int newlevel;
/*
* Only update loglevel value when a correct setting was passed,
* to prevent blind crashes (when loglevel being set to 0) that
* are quite hard to debug
*/
if (get_option(&str, &newlevel)) {
console_loglevel = newlevel;
return 0;
}
return -EINVAL;
}
early_param("loglevel", loglevel);
/* Change NUL term back to "=", to make "param" the whole string. */
static int __init repair_env_string(char *param, char *val)
{
if (val) {
/* param=val or param="val"? */
if (val == param+strlen(param)+1)
val[-1] = '=';
else if (val == param+strlen(param)+2) {
val[-2] = '=';
memmove(val-1, val, strlen(val)+1);
val--;
} else
BUG();
}
return 0;
}
/*
* Unknown boot options get handed to init, unless they look like
* unused parameters (modprobe will find them in /proc/cmdline).
*/
static int __init unknown_bootoption(char *param, char *val)
{
repair_env_string(param, val);
/* Handle obsolete-style parameters */
if (obsolete_checksetup(param))
return 0;
/* Unused module parameter. */
if (strchr(param, '.') && (!val || strchr(param, '.') < val))
return 0;
if (panic_later)
return 0;
if (val) {
/* Environment option */
unsigned int i;
for (i = 0; envp_init[i]; i++) {
if (i == MAX_INIT_ENVS) {
panic_later = "Too many boot env vars at `%s'";
panic_param = param;
}
if (!strncmp(param, envp_init[i], val - param))
break;
}
envp_init[i] = param;
} else {
/* Command line option */
unsigned int i;
for (i = 0; argv_init[i]; i++) {
if (i == MAX_INIT_ARGS) {
panic_later = "Too many boot init vars at `%s'";
panic_param = param;
}
}
argv_init[i] = param;
}
return 0;
}
static int __init init_setup(char *str)
{
unsigned int i;
execute_command = str;
/*
* In case LILO is going to boot us with default command line,
* it prepends "auto" before the whole cmdline which makes
* the shell think it should execute a script with such name.
* So we ignore all arguments entered _before_ init=... [MJ]
*/
for (i = 1; i < MAX_INIT_ARGS; i++)
argv_init[i] = NULL;
return 1;
}
__setup("init=", init_setup);
static int __init rdinit_setup(char *str)
{
unsigned int i;
ramdisk_execute_command = str;
/* See "auto" comment in init_setup */
for (i = 1; i < MAX_INIT_ARGS; i++)
argv_init[i] = NULL;
return 1;
}
__setup("rdinit=", rdinit_setup);
#ifndef CONFIG_SMP
static const unsigned int setup_max_cpus = NR_CPUS;
#ifdef CONFIG_X86_LOCAL_APIC
static void __init smp_init(void)
{
APIC_init_uniprocessor();
}
#else
#define smp_init() do { } while (0)
#endif
static inline void setup_nr_cpu_ids(void) { }
static inline void smp_prepare_cpus(unsigned int maxcpus) { }
#endif
/*
* We need to store the untouched command line for future reference.
* We also need to store the touched command line since the parameter
* parsing is performed in place, and we should allow a component to
* store reference of name/value for future reference.
*/
static void __init setup_command_line(char *command_line)
{
saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
static_command_line = alloc_bootmem(strlen (command_line)+1);
strcpy (saved_command_line, boot_command_line);
strcpy (static_command_line, command_line);
}
/*
* We need to finalize in a non-__init function or else race conditions
* between the root thread and the init thread may cause start_kernel to
* be reaped by free_initmem before the root thread has proceeded to
* cpu_idle.
*
* gcc-3.4 accidentally inlines this function, so use noinline.
*/
static __initdata DECLARE_COMPLETION(kthreadd_done);
static noinline void __init_refok rest_init(void)
{
int pid;
rcu_scheduler_starting();//READ-COPY UPDATE
/*
* We need to spawn init first so that it obtains pid 1, however
* the init task will end up wanting to create kthreads, which, if
* we schedule it before we create kthreadd, will OOPS.
* ， kernel_init,pid=1,
*/
kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
//numa
numa_default_policy();
// kthread_create_list kthread
//kthreadd
pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
rcu_read_lock();
// pid,ini_pid_ns kthreadd
kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
rcu_read_unlock();
// kthreadd_done kernel_init
complete(&kthreadd_done);
/*
* The boot idle thread must execute schedule()
* at least once to get things moving:
* idle
*/
init_idle_bootup_task(current);
//
schedule_preempt_disabled();
/* Call into cpu_idle with preempt disabled */
cpu_idle();
}
/* Check for early params. */
static int __init do_early_param(char *param, char *val)
{
const struct obs_kernel_param *p;
for (p = __setup_start; p < __setup_end; p++) {
if ((p->early && parameq(param, p->str)) ||
(strcmp(param, "console") == 0 &&
strcmp(p->str, "earlycon") == 0)
) {
if (p->setup_func(val) != 0)
printk(KERN_WARNING
"Malformed early option '%s'
", param);
}
}
/* We accept everything at this stage. */
return 0;
}
void __init parse_early_options(char *cmdline)
{
parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
}
/* Arch code calls this early on, or if not, just before other parsing. */
void __init parse_early_param(void)
{
static __initdata int done = 0;
static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
if (done)
return;
/* All fall through to do_early_param. */
strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
parse_early_options(tmp_cmdline);
done = 1;
}
/*
* Activate the first processor.
*/
static void __init boot_cpu_init(void)
{
int cpu = smp_processor_id();
/* Mark the boot cpu "present", "online" etc for SMP and UP case */
set_cpu_online(cpu, true);
set_cpu_active(cpu, true);
set_cpu_present(cpu, true);
set_cpu_possible(cpu, true);
}
void __init __weak smp_setup_processor_id(void)
{
}
void __init __weak thread_info_cache_init(void)
{
}
/*
* Set up kernel memory allocators
*/
static void __init mm_init(void)
{
/*
* page_cgroup requires contiguous pages,
* bigger than MAX_ORDER unless SPARSEMEM.
*/
page_cgroup_init_flatmem();
mem_init();
kmem_cache_init();
percpu_init_late();
pgtable_cache_init();
vmalloc_init();
}
asmlinkage void __init start_kernel(void)
{
char * command_line;
extern const struct kernel_param __start___param[], __stop___param[];
/*
* Need to run as early as possible, to initialize the
* lockdep hash:
*/
// 2 hash -Lock Dependency Validator( )
lockdep_init();
smp_setup_processor_id(); //
debug_objects_early_init();//
/*
* Set up the the initial canary ASAP:
*/
boot_init_stack_canary();//
// -cgroup-
cgroup_init_early();
local_irq_disable();//
early_boot_irqs_disabled = true;
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
tick_init();//
boot_cpu_init();// cpu
page_address_init();//
printk(KERN_NOTICE "%s", linux_banner);
setup_arch(&command_line);//
mm_init_owner(&init_mm, &init_task);//
mm_init_cpumask(&init_mm);//
setup_command_line(command_line);// ( 2 )
setup_nr_cpu_ids();//cpuid
setup_per_cpu_areas();// cpu ( gdt)
//smp cpu
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
//
build_all_zonelists(NULL);
//
page_alloc_init();
printk(KERN_NOTICE "Kernel command line: %s
", boot_command_line);
// boot_command_line
parse_early_param();
//
parse_args("Booting kernel", static_command_line, __start___param,
__stop___param - __start___param,
-1, -1, &unknown_bootoption);
//
jump_label_init();
/*
* These use large bootmem allocations and must precede
* kmem_cache_init()
*
*/
setup_log_buf(0);
pidhash_init();
vfs_caches_init_early();
sort_main_extable();
trap_init();
mm_init();
/*
* Set up the scheduler prior starting any interrupts (such as the
* timer interrupt). Full topology setup happens at smp_init()
* time - but meanwhile we still have a functioning scheduler.
*
*/
sched_init();
/*
* Disable preemption - early bootup scheduling is extremely
* fragile until we cpu_idle() for the first time.
*
*/
preempt_disable();
if (!irqs_disabled()) {
printk(KERN_WARNING "start_kernel(): bug: interrupts were "
"enabled *very* early, fixing it
");
local_irq_disable();
}
idr_init_cache();//idr
perf_event_init();//performance event
rcu_init();//read-copy-update
radix_tree_init();//radix
/* init some links before init_ISA_irqs() */
early_irq_init();//
init_IRQ();//
prio_tree_init();//
init_timers();//
hrtimers_init();//High-resolution kernel timers
softirq_init();//
timekeeping_init();//
time_init();//
profile_init();//
call_function_init();//smp cpu call_single_queue
if (!irqs_disabled())
printk(KERN_CRIT "start_kernel(): bug: interrupts were "
"enabled early
");
early_boot_irqs_disabled = false;//
local_irq_enable();//
kmem_cache_init_late();//kmem
/*
* HACK ALERT! This is early. We're enabling the console before
* we've done PCI setups etc, and console_init() must be aware of
* this. But we do want output early, in case something goes wrong.
*/
console_init();//
if (panic_later)
panic(panic_later, panic_param);
//
lockdep_info();
/*
* Need to run this when irqs are enabled, because it wants
* to self-test [hard/soft]-irqs on/off lock inversion bugs
* too:
*/
locking_selftest();
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
"disabling it.
",
page_to_pfn(virt_to_page((void *)initrd_start)),
min_low_pfn);
initrd_start = 0;
}
#endif
page_cgroup_init();//control groups
debug_objects_mem_init();//
kmemleak_init();//
setup_per_cpu_pageset();// cpu set
numa_policy_init();//numa
if (late_time_init)
late_time_init();
// cpusched_clock_data=ktime_now
sched_clock_init();
calibrate_delay();// cpuMIPS /s
pidmap_init();//pid id
anon_vma_init();//
#ifdef CONFIG_X86
if (efi_enabled)//efi bois
efi_enter_virtual_mode();
#endif
thread_info_cache_init();// thread_info
cred_init();//credential
// ， /
fork_init(totalram_pages);
proc_caches_init();//
buffer_init();//
key_init();// ， keys
security_init();//
dbg_late_init();//
vfs_caches_init(totalram_pages);//
signals_init();//sigqueue ，
/* rootfs populating might need page-writeback */
page_writeback_init();//
#ifdef CONFIG_PROC_FS
proc_root_init();//proc
#endif
cgroup_init();//cgroup
cpuset_init();//cpuset
taskstats_init_early();//
delayacct_init();//
check_bugs();// bug
//acpi
acpi_early_init(); /* before LAPIC and SMP init */
sfi_init_late();//Simple Firmware Interface
// ,
ftrace_init();
/* Do the rest non-__init'ed, we're now alive */
rest_init();
}
/* Call all constructor functions linked into the kernel. */
static void __init do_ctors(void)
{
#ifdef CONFIG_CONSTRUCTORS
ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
for (; fn < (ctor_fn_t *) __ctors_end; fn++)
(*fn)();
#endif
}
bool initcall_debug;
core_param(initcall_debug, initcall_debug, bool, 0644);
static char msgbuf[64];
static int __init_or_module do_one_initcall_debug(initcall_t fn)
{
ktime_t calltime, delta, rettime;
unsigned long long duration;
int ret;
printk(KERN_DEBUG "calling %pF @ %i
", fn, task_pid_nr(current));
calltime = ktime_get();
ret = fn();
rettime = ktime_get();
delta = ktime_sub(rettime, calltime);
duration = (unsigned long long) ktime_to_ns(delta) >> 10;
printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs
", fn,
ret, duration);
return ret;
}
int __init_or_module do_one_initcall(initcall_t fn)
{
int count = preempt_count();
int ret;
if (initcall_debug)
ret = do_one_initcall_debug(fn);
else
ret = fn();
msgbuf[0] = 0;
if (ret && ret != -ENODEV && initcall_debug)
sprintf(msgbuf, "error code %d ", ret);
if (preempt_count() != count) {
strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
preempt_count() = count;
}
if (irqs_disabled()) {
strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
local_irq_enable();
}
if (msgbuf[0]) {
printk("initcall %pF returned with %s
", fn, msgbuf);
}
return ret;
}
extern initcall_t __initcall_start[];
extern initcall_t __initcall0_start[];
extern initcall_t __initcall1_start[];
extern initcall_t __initcall2_start[];
extern initcall_t __initcall3_start[];
extern initcall_t __initcall4_start[];
extern initcall_t __initcall5_start[];
extern initcall_t __initcall6_start[];
extern initcall_t __initcall7_start[];
extern initcall_t __initcall_end[];
static initcall_t *initcall_levels[] __initdata = {
__initcall0_start,
__initcall1_start,
__initcall2_start,
__initcall3_start,
__initcall4_start,
__initcall5_start,
__initcall6_start,
__initcall7_start,
__initcall_end,
};
static char *initcall_level_names[] __initdata = {
"early parameters",
"core parameters",
"postcore parameters",
"arch parameters",
"subsys parameters",
"fs parameters",
"device parameters",
"late parameters",
};
static void __init do_initcall_level(int level)
{
extern const struct kernel_param __start___param[], __stop___param[];
initcall_t *fn;
strcpy(static_command_line, saved_command_line);
parse_args(initcall_level_names[level],
static_command_line, __start___param,
__stop___param - __start___param,
level, level,
repair_env_string);
for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
do_one_initcall(*fn);
}
static void __init do_initcalls(void)
{
int level;
for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
do_initcall_level(level);
}
/*
* Ok, the machine is now initialized. None of the devices
* have been touched yet, but the CPU subsystem is up and
* running, and memory and process management works.
*
* Now we can finally start doing some real work..
*/
static void __init do_basic_setup(void)
{
cpuset_init_smp();//smp cpuset
usermodehelper_init();//khelper
shmem_init();//sheme
driver_init();//
init_irq_proc();//proc irq
do_ctors();// , .ctors
usermodehelper_enable();
//
do_initcalls();
}
static void __init do_pre_smp_initcalls(void)
{
initcall_t *fn;
for (fn = __initcall_start; fn < __initcall0_start; fn++)
do_one_initcall(*fn);
}
static void run_init_process(const char *init_filename)
{
argv_init[0] = init_filename;
kernel_execve(init_filename, argv_init, envp_init);
}
/* This is a non __init function. Force it to be noinline otherwise gcc
* makes it inline to init() and it becomes part of init.text section
* Init ， gcc init()， Init.text
*/
static noinline int init_post(void)
{
/* need to finish all async __init code before freeing the memory
* init ， __init
*/
async_synchronize_full();
free_initmem();// init.*
// ， read only
mark_rodata_ro();
//
system_state = SYSTEM_RUNNING;
//numa
numa_default_policy();
// ， init
current->signal->flags |= SIGNAL_UNKILLABLE;
// ramdisk_execute_command init ，
if (ramdisk_execute_command) {
run_init_process(ramdisk_execute_command);
printk(KERN_WARNING "Failed to execute %s
",
ramdisk_execute_command);
}
/*
* We try each of these until one succeeds.
*
* The Bourne shell can be used instead of init if we are
* trying to recover a really broken machine.
* ， ， ， 4
*/
if (execute_command) {
run_init_process(execute_command);
printk(KERN_WARNING "Failed to execute %s. Attempting "
"defaults...
", execute_command);
}
run_init_process("/sbin/init");
run_init_process("/etc/init");
run_init_process("/bin/init");
run_init_process("/bin/sh");
// 4 init ，
panic("No init found. Try passing init= option to kernel. "
"See Linux Documentation/init.txt for guidance.");
}
static int __init kernel_init(void * unused)
{
/*
* Wait until kthreadd is all set-up. kthreadd
*/
wait_for_completion(&kthreadd_done);
/* Now the scheduler is fully set up and can do blocking allocations
*
*/
gfp_allowed_mask = __GFP_BITS_MASK;
/*
* init can allocate pages on any node
*/
set_mems_allowed(node_states[N_HIGH_MEMORY]);
/*
* init can run on any cpu.
*/
set_cpus_allowed_ptr(current, cpu_all_mask);
//cad_pid Ctrl-alt-del INT ID, init pid
// init 3
cad_pid = task_pid(current);
//smp 、 cpu
smp_prepare_cpus(setup_max_cpus);
do_pre_smp_initcalls();
lockup_detector_init();
smp_init();
sched_init_smp();
// 、
do_basic_setup();
/* Open the /dev/console on the rootfs, this should never fail
* /dev/console
*/
if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
printk(KERN_WARNING "Warning: unable to open an initial console.
");
/*
* 0， 1， 2
*/
(void) sys_dup(0);
(void) sys_dup(0);
/*
* check if there is an early userspace init. If yes, let it do all
* the work
* init ， ，
*/
if (!ramdisk_execute_command)
ramdisk_execute_command = "/init";
if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
ramdisk_execute_command = NULL;
prepare_namespace();
}
/*
* Ok, we have completed the initial bootup, and
* we're essentially up and running. Get rid of the
* initmem segments and start the user-mode stuff..
*/
// init
init_post();
return 0;
} 이 내용에 흥미가 있습니까?
현재 기사가 여러분의 문제를 해결하지 못하는 경우 AI 엔진은 머신러닝 분석(스마트 모델이 방금 만들어져 부정확한 경우가 있을 수 있음)을 통해 가장 유사한 기사를 추천합니다:
아날로그 파일 시스템그 중에서 대응하는 파일의 파일 형식, 파일 크기, 차지하는 디스크 블록의 수, 그리고 차지하는 디스크 블록 번호를 저장합니다.그리고 매번 파일에 대한 읽기와 쓰기는 해당하는inode의 내용과 대응하는 디스크 블록의...
텍스트를 자유롭게 공유하거나 복사할 수 있습니다.하지만 이 문서의 URL은 참조 URL로 남겨 두십시오.
CC BY-SA 2.5, CC BY-SA 3.0 및 CC BY-SA 4.0에 따라 라이센스가 부여됩니다.
좋은 웹페이지 즐겨찾기
