以Linux为基准通过VSCODE来看微软和谷歌代码风格差异
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下面差异部分从左到右依次是Linux，Microsoft，Google的排版（这里仅仅是自动化排版风格，不涉及编码规范命名方式等内容）。对比来对比去，最后发现还是看Linux的代码排版方式比较舒服，Linux内核clang-format排版配置文件，放在这里（重命名为.clang-format直接放到VSCODE工作区下面即可），拿走不谢。
VSCODE输出窗口“C/C++”，错误提示信息如下(更多错误提示的处理可以看评论区)
正确格式应该是：
"c:\\Users\\jason\\.vscode\\extensions\\ms-vscode.cpptools-1.9.8-win32-x64/bin/../LLVM/bin/clang-format.exe" -style="file" -fallback-style="visual studio" -offset=3587 -length=275 -assume-filename="D:\\test\\user_main.c"同理可以在Source Insight里添加自定义命令如下：
同时，Linux Kernel官方也有提到，clang-format总体上还是值得肯定的，但是有些地方也会覆盖不到，所以它不适合遍历目录对所有的文件统一进行格式化，甚至个别目录的风格和其它地方是不一样的，这些目录下需要有单独的.clang-format配置文件。对于熟悉代码的人来说，这些地方都是显而易见的，只要不滥用clang-format，也很容避免这些问题。
比如，下面的代码对齐方式在Linux内核源码里非常的普遍，用clang-format格式化后可能会打乱原来的风格。
格式化前
#define TRACING_MAP_BITS_DEFAULT 11 #define TRACING_MAP_BITS_MAX 17 #define TRACING_MAP_BITS_MIN 7格式化后
#define TRACING_MAP_BITS_DEFAULT 11 #define TRACING_MAP_BITS_MAX 17 #define TRACING_MAP_BITS_MIN 7格式化前
static const struct file_operations uprobe_events_ops = .owner = THIS_MODULE, .open = probes_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, .write = probes_write, ;格式化后
static const struct file_operations uprobe_events_ops = .owner = THIS_MODULE, .open = probes_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, .write = probes_write, ;
1. Google将头文件引用部分自动按照首字母升序进行排列，在有先后依赖关系的情况下可能会影响编译（单击图片可以看到清晰对比图）
2. 括号、 循环语句、条件判断、单行长度（单击图片可以看到清晰对比图）
3. 函数和数组（单击图片可以看到清晰对比图）
下面是Linux内核源码main.c 一共1048行
/*
* 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 <grif@acm.org>
*/
#define DEBUG /* Enable initcall_debug */
#include <linux/types.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/stackprotector.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/bootmem.h>
#include <linux/acpi.h>
#include <linux/tty.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
#include <linux/vmalloc.h>
#include <linux/kernel_stat.h>
#include <linux/start_kernel.h>
#include <linux/security.h>
#include <linux/smp.h>
#include <linux/profile.h>
#include <linux/rcupdate.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/writeback.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/cgroup.h>
#include <linux/efi.h>
#include <linux/tick.h>
#include <linux/interrupt.h>
#include <linux/taskstats_kern.h>
#include <linux/delayacct.h>
#include <linux/unistd.h>
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>
#include <linux/buffer_head.h>
#include <linux/page_ext.h>
#include <linux/debug_locks.h>
#include <linux/debugobjects.h>
#include <linux/lockdep.h>
#include <linux/kmemleak.h>
#include <linux/pid_namespace.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/idr.h>
#include <linux/kgdb.h>
#include <linux/ftrace.h>
#include <linux/async.h>
#include <linux/kmemcheck.h>
#include <linux/sfi.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/perf_event.h>
#include <linux/file.h>
#include <linux/ptrace.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/sched_clock.h>
#include <linux/context_tracking.h>
#include <linux/random.h>
#include <linux/list.h>
#include <linux/integrity.h>
#include <linux/proc_ns.h>
#include <linux/io.h>
#include <asm/io.h>
#include <asm/bugs.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
static int kernel_init(void *);
extern void init_IRQ(void);
extern void fork_init(void);
extern void radix_tree_init(void);
/*
* 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);
/* 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;
/* Command line for per-initcall parameter parsing */
static char *initcall_command_line;
static char *execute_command;
static char *ramdisk_execute_command;
/*
* Used to generate warnings if static_key manipulation functions are used
* before jump_label_init is called.
*/
bool static_key_initialized __read_mostly;
EXPORT_SYMBOL_GPL(static_key_initialized);
/*
* 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 situation 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 bool __init obsolete_checksetup(char *line)
const struct obs_kernel_param *p;
bool had_early_param = false;
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 = true;
else if (!p->setup_func)
pr_warn("Parameter %s is obsolete, ignored\\n",
p->str);
return true;
else if (p->setup_func(line + n))
return true;
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 = CONSOLE_LOGLEVEL_DEBUG;
return 0;
static int __init quiet_kernel(char *str)
console_loglevel = CONSOLE_LOGLEVEL_QUIET;
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,
const char *unused, void *arg)
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;
/* Anything after -- gets handed straight to init. */
static int __init set_init_arg(char *param, char *val,
const char *unused, void *arg)
unsigned int i;
if (panic_later)
return 0;
repair_env_string(param, val, unused, NULL);
for (i = 0; argv_init[i]; i++)
if (i == MAX_INIT_ARGS)
panic_later = "init";
panic_param = param;
return 0;
argv_init[i] = param;
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,
const char *unused, void *arg)
repair_env_string(param, val, unused, NULL);
/* 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 = "env";
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 = "init";
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;
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 =
memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
initcall_command_line =
memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
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 __ref rest_init(void)
int pid;
rcu_scheduler_starting();
/*
* 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_thread(kernel_init, NULL, CLONE_FS);
numa_default_policy();
pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
rcu_read_lock();
kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
rcu_read_unlock();
complete(&kthreadd_done);
/*
* The boot idle thread must execute schedule()
* at least once to get things moving:
*/
init_idle_bootup_task(current);
schedule_preempt_disabled();
/* Call into cpu_idle with preempt disabled */
cpu_startup_entry(CPUHP_ONLINE);
/* Check for early params. */
static int __init do_early_param(char *param, char *val,
const char *unused, void *arg)
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)
pr_warn("Malformed early option '%s'\\n", 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, NULL,
do_early_param);
/* Arch code calls this early on, or if not, just before other parsing. */
void __init parse_early_param(void)
static int done __initdata;
static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
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;
void __init __weak smp_setup_processor_id(void)
# if THREAD_SIZE >= PAGE_SIZE
void __init __weak thread_stack_cache_init(void)
#endif
/*
* Set up kernel memory allocators
*/
static void __init mm_init(void)
/*
* page_ext requires contiguous pages,
* bigger than MAX_ORDER unless SPARSEMEM.
*/
page_ext_init_flatmem();
mem_init();
kmem_cache_init();
percpu_init_late();
pgtable_init();
vmalloc_init();
ioremap_huge_init();
asmlinkage __visible void __init start_kernel(void)
char *command_line;
char *after_dashes;
set_task_stack_end_magic(&init_task);
smp_setup_processor_id();
debug_objects_early_init();
/*
* Set up the the initial canary ASAP:
*/
boot_init_stack_canary();
cgroup_init_early();
local_irq_disable();
early_boot_irqs_disabled = true;
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
boot_cpu_init();
page_address_init();
pr_notice("%s", linux_banner);
setup_arch(&command_line);
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
boot_cpu_state_init();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
build_all_zonelists(NULL, NULL);
page_alloc_init();
pr_notice("Kernel command line: %s\\n", boot_command_line);
parse_early_param();
after_dashes = parse_args("Booting kernel",
static_command_line, __start___param,
__stop___param - __start___param,
-1, -1, NULL, &unknown_bootoption);
if (!IS_ERR_OR_NULL(after_dashes))
parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
NULL, set_init_arg);
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 (WARN(!irqs_disabled(),
"Interrupts were enabled *very* early, fixing it\\n"))
local_irq_disable();
idr_init_cache();
rcu_init();
/* trace_printk() and trace points may be used after this */
trace_init();
context_tracking_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
early_irq_init();
init_IRQ();
tick_init();
rcu_init_nohz();
init_timers();
hrtimers_init();
softirq_init();
timekeeping_init();
time_init();
sched_clock_postinit();
printk_nmi_init();
perf_event_init();
profile_init();
call_function_init();
WARN(!irqs_disabled(), "Interrupts were enabled early\\n");
early_boot_irqs_disabled = false;
local_irq_enable();
kmem_cache_init_late();
/*
* 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("Too many boot %s vars at `%s'", 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)
pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\\n",
page_to_pfn(virt_to_page((void *)initrd_start)),
min_low_pfn);
initrd_start = 0;
#endif
page_ext_init();
debug_objects_mem_init();
kmemleak_init();
setup_per_cpu_pageset();
numa_policy_init();
if (late_time_init)
late_time_init();
sched_clock_init();
calibrate_delay();
pidmap_init();
anon_vma_init();
acpi_early_init();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
#endif
#ifdef CONFIG_X86_ESPFIX64
/* Should be run before the first non-init thread is created */
init_espfix_bsp();
#endif
thread_stack_cache_init();
cred_init();
fork_init();
proc_caches_init();
buffer_init();
key_init();
security_init();
dbg_late_init();
vfs_caches_init();
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();
proc_root_init();
nsfs_init();
cpuset_init();
cgroup_init();
taskstats_init_early();
delayacct_init();
check_bugs();
acpi_subsystem_init();
sfi_init_late();
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_late_init();
efi_free_boot_services();
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);
#ifdef CONFIG_KALLSYMS
struct blacklist_entry
struct list_head next;
char *buf;
;
static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
static int __init initcall_blacklist(char *str)
char *str_entry;
struct blacklist_entry *entry;
/* str argument is a comma-separated list of functions */
do
str_entry = strsep(&str, ",");
if (str_entry)
pr_debug("blacklisting initcall %s\\n", str_entry);
entry = alloc_bootmem(sizeof(*entry));
entry->buf = alloc_bootmem(strlen(str_entry) + 1);
strcpy(entry->buf, str_entry);
list_add(&entry->next, &blacklisted_initcalls);
while (str_entry);
return 0;
static bool __init_or_module initcall_blacklisted(initcall_t fn)
struct blacklist_entry *entry;
char fn_name[KSYM_SYMBOL_LEN];
unsigned long addr;
if (list_empty(&blacklisted_initcalls))
return false;
addr = (unsigned long) dereference_function_descriptor(fn);
sprint_symbol_no_offset(fn_name, addr);
/*
* fn will be "function_name [module_name]" where [module_name] is not
* displayed for built-in init functions. Strip off the [module_name].
*/
strreplace(fn_name, ' ', '\\0');
list_for_each_entry(entry, &blacklisted_initcalls, next)
if (!strcmp(fn_name, entry->buf))
pr_debug("initcall %s blacklisted\\n", fn_name);
return true;
return false;
#else
static int __init initcall_blacklist(char *str)
pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\\n");
return 0;
static bool __init_or_module initcall_blacklisted(initcall_t fn)
return false;
#endif
__setup("initcall_blacklist=", initcall_blacklist);
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\\n", 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\\n",
fn, ret, duration);
return ret;
int __init_or_module do_one_initcall(initcall_t fn)
int count = preempt_count();
int ret;
char msgbuf[64];
if (initcall_blacklisted(fn))
return -EPERM;
if (initcall_debug)
ret = do_one_initcall_debug(fn);
else
ret = fn();
msgbuf[0] = 0;
if (preempt_count() != count)
sprintf(msgbuf, "preemption imbalance ");
preempt_count_set(count);
if (irqs_disabled())
strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
local_irq_enable();
WARN(msgbuf[0], "initcall %pF returned with %s\\n", fn, msgbuf);
add_latent_entropy();
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,
;
/* Keep these in sync with initcalls in include/linux/init.h */
static char *initcall_level_names[] __initdata =
"early",
"core",
"postcore",
"arch",
"subsys",
"fs",
"device",
"late",
;
static void __init do_initcall_level(int level)
initcall_t *fn;
strcpy(initcall_command_line, saved_command_line);
parse_args(initcall_level_names[level],
initcall_command_line, __start___param,
__stop___param - __start___param,
level, level,
NULL, &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();
shmem_init();
driver_init();
init_irq_proc();
do_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);
/*
* This function requests modules which should be loaded by default and is
* called twice right after initrd is mounted and right before init is
* exec'd. If such modules are on either initrd or rootfs, they will be
* loaded before control is passed to userland.
*/
void __init load_default_modules(void)
load_default_elevator_module();
static int run_init_process(const char *init_filename)
argv_init[0] = init_filename;
return do_execve(getname_kernel(init_filename),
(const char __user *const __user *)argv_init,
(const char __user *const __user *)envp_init);
static int try_to_run_init_process(const char *init_filename)
int ret;
ret = run_init_process(init_filename);
if (ret && ret != -ENOENT)
pr_err("Starting init: %s exists but couldn't execute it (error %d)\\n",
init_filename, ret);
return ret;
static noinline void __init kernel_init_freeable(void);
#ifdef CONFIG_DEBUG_RODATA
static bool rodata_enabled = true;
static int __init set_debug_rodata(char *str)
return strtobool(str, &rodata_enabled);
__setup("rodata=", set_debug_rodata);
static void mark_readonly(void)
if (rodata_enabled)
mark_rodata_ro();
else
pr_info("Kernel memory protection disabled.\\n");
#else
static inline void mark_readonly(void)
pr_warn("This architecture does not have kernel memory protection.\\n");
#endif
static int __ref kernel_init(void *unused)
int ret;
kernel_init_freeable();
/* need to finish all async __init code before freeing the memory */
async_synchronize_full();
free_initmem();
mark_readonly();
system_state = SYSTEM_RUNNING;
numa_default_policy();
flush_delayed_fput();
rcu_end_inkernel_boot();
if (ramdisk_execute_command)
ret = run_init_process(ramdisk_execute_command);
if (!ret)
return 0;
pr_err("Failed to execute %s (error %d)\\n",
ramdisk_execute_command, ret);
/*
* 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.
*/
if (execute_command)
ret = run_init_process(execute_command);
if (!ret)
return 0;
panic("Requested init %s failed (error %d).",
execute_command, ret);
if (!try_to_run_init_process("/sbin/init") ||
!try_to_run_init_process("/etc/init") ||
!try_to_run_init_process("/bin/init") ||
!try_to_run_init_process("/bin/sh"))
return 0;
panic("No working init found. Try passing init= option to kernel. "
"See Linux Documentation/init.txt for guidance.");
static noinline void __init kernel_init_freeable(void)
/*
* Wait until kthreadd is all set-up.
*/
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_MEMORY]);
/*
* init can run on any cpu.
*/
set_cpus_allowed_ptr(current, cpu_all_mask);
cad_pid = task_pid(current);
smp_prepare_cpus(setup_max_cpus);
do_pre_smp_initcalls();
lockup_detector_init();
smp_init();
sched_init_smp();
page_alloc_init_late();
do_basic_setup();
/* Open the /dev/console on the rootfs, this should never fail */
if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
pr_err("Warning: unable to open an initial console.\\n");
(void) sys_dup(0);
(void) sys_dup(0);
/*
* check if there is an early userspace init. If yes, let it do all
* the work
*/
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..
*
* rootfs is available now, try loading the public keys
* and default modules
*/
integrity_load_keys();
load_default_modules();
下面是Google风格，格式化后969行
/*
* 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 <grif@acm.org>
*/
#define DEBUG /* Enable initcall_debug */
#include <linux/types.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/stackprotector.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/bootmem.h>
#include <linux/acpi.h>
#include <linux/tty.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
#include <linux/vmalloc.h>
#include <linux/kernel_stat.h>
#include <linux/start_kernel.h>
#include <linux/security.h>
#include <linux/smp.h>
#include <linux/profile.h>
#include <linux/rcupdate.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/writeback.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/cgroup.h>
#include <linux/efi.h>
#include <linux/tick.h>
#include <linux/interrupt.h>
#include <linux/taskstats_kern.h>
#include <linux/delayacct.h>
#include <linux/unistd.h>
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>
#include <linux/buffer_head.h>
#include <linux/page_ext.h>
#include <linux/debug_locks.h>
#include <linux/debugobjects.h>
#include <linux/lockdep.h>
#include <linux/kmemleak.h>
#include <linux/pid_namespace.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/idr.h>
#include <linux/kgdb.h>
#include <linux/ftrace.h>
#include <linux/async.h>
#include <linux/kmemcheck.h>
#include <linux/sfi.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/perf_event.h>
#include <linux/file.h>
#include <linux/ptrace.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/sched_clock.h>
#include <linux/context_tracking.h>
#include <linux/random.h>
#include <linux/list.h>
#include <linux/integrity.h>
#include <linux/proc_ns.h>
#include <linux/io.h>
#include <asm/io.h>
#include <asm/bugs.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
static int kernel_init(void *);
extern void init_IRQ(void);
extern void fork_init(void);
extern void radix_tree_init(void);
/*
* 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);
/* 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;
/* Command line for per-initcall parameter parsing */
static char *initcall_command_line;
static char *execute_command;
static char *ramdisk_execute_command;
/*
* Used to generate warnings if static_key manipulation functions are used
* before jump_label_init is called.
*/
bool static_key_initialized __read_mostly;
EXPORT_SYMBOL_GPL(static_key_initialized);
/*
* 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 situation 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 bool __init obsolete_checksetup(char *line)
const struct obs_kernel_param *p;
bool had_early_param = false;
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 = true;
else if (!p->setup_func)
pr_warn("Parameter %s is obsolete, ignored\\n",
p->str);
return true;
else if (p->setup_func(line + n))
return true;
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 = CONSOLE_LOGLEVEL_DEBUG;
return 0;
static int __init quiet_kernel(char *str)
console_loglevel = CONSOLE_LOGLEVEL_QUIET;
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,
const char *unused, void *arg)
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;
/* Anything after -- gets handed straight to init. */
static int __init set_init_arg(char *param, char *val,
const char *unused, void *arg)
unsigned int i;
if (panic_later)
return 0;
repair_env_string(param, val, unused, NULL);
for (i = 0; argv_init[i]; i++)
if (i == MAX_INIT_ARGS)
panic_later = "init";
panic_param = param;
return 0;
argv_init[i] = param;
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,
const char *unused, void *arg)
repair_env_string(param, val, unused, NULL);
/* 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 = "env";
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 = "init";
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;
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 =
memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
initcall_command_line =
memblock_virt_alloc(strlen(boot_command_line) + 1, 0);
static_command_line = memblock_virt_alloc(strlen(command_line) + 1, 0);
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 __ref rest_init(void)
int pid;
rcu_scheduler_starting();
/*
* 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_thread(kernel_init, NULL, CLONE_FS);
numa_default_policy();
pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
rcu_read_lock();
kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
rcu_read_unlock();
complete(&kthreadd_done);
/*
* The boot idle thread must execute schedule()
* at least once to get things moving:
*/
init_idle_bootup_task(current);
schedule_preempt_disabled();
/* Call into cpu_idle with preempt disabled */
cpu_startup_entry(CPUHP_ONLINE);
/* Check for early params. */
static int __init do_early_param(char *param, char *val,
const char *unused, void *arg)
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)
pr_warn("Malformed early option '%s'\\n", 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, NULL,
do_early_param);
/* Arch code calls this early on, or if not, just before other parsing. */
void __init parse_early_param(void)
static int done __initdata;
static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
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;
void __init __weak smp_setup_processor_id(void)
# if THREAD_SIZE >= PAGE_SIZE
void __init __weak thread_stack_cache_init(void)
#endif
/*
* Set up kernel memory allocators
*/
static void __init mm_init(void)
/*
* page_ext requires contiguous pages,
* bigger than MAX_ORDER unless SPARSEMEM.
*/
page_ext_init_flatmem();
mem_init();
kmem_cache_init();
percpu_init_late();
pgtable_init();
vmalloc_init();
ioremap_huge_init();
asmlinkage __visible void __init start_kernel(void)
char *command_line;
char *after_dashes;
set_task_stack_end_magic(&init_task);
smp_setup_processor_id();
debug_objects_early_init();
/*
* Set up the the initial canary ASAP:
*/
boot_init_stack_canary();
cgroup_init_early();
local_irq_disable();
early_boot_irqs_disabled = true;
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
*/
boot_cpu_init();
page_address_init();
pr_notice("%s", linux_banner);
setup_arch(&command_line);
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
boot_cpu_state_init();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
build_all_zonelists(NULL, NULL);
page_alloc_init();
pr_notice("Kernel command line: %s\\n", boot_command_line);
parse_early_param();
after_dashes = parse_args("Booting kernel",
static_command_line, __start___param,
__stop___param - __start___param,
-1, -1, NULL, &unknown_bootoption);
if (!IS_ERR_OR_NULL(after_dashes))
parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
NULL, set_init_arg);
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 (WARN(!irqs_disabled(),
"Interrupts were enabled *very* early, fixing it\\n"))
local_irq_disable();
idr_init_cache();
rcu_init();
/* trace_printk() and trace points may be used after this */
trace_init();
context_tracking_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
early_irq_init();
init_IRQ();
tick_init();
rcu_init_nohz();
init_timers();
hrtimers_init();
softirq_init();
timekeeping_init();
time_init();
sched_clock_postinit();
printk_nmi_init();
perf_event_init();
profile_init();
call_function_init();
WARN(!irqs_disabled(), "Interrupts were enabled early\\n");
early_boot_irqs_disabled = false;
local_irq_enable();
kmem_cache_init_late();
/*
* 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("Too many boot %s vars at `%s'", 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)
pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\\n",
page_to_pfn(virt_to_page((void *)initrd_start)),
min_low_pfn);
initrd_start = 0;
#endif
page_ext_init();
debug_objects_mem_init();
kmemleak_init();
setup_per_cpu_pageset();
numa_policy_init();
if (late_time_init)
late_time_init();
sched_clock_init();
calibrate_delay();
pidmap_init();
anon_vma_init();
acpi_early_init();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
#endif
#ifdef CONFIG_X86_ESPFIX64
/* Should be run before the first non-init thread is created */
init_espfix_bsp();
#endif
thread_stack_cache_init();
cred_init();
fork_init();
proc_caches_init();
buffer_init();
key_init();
security_init();
dbg_late_init();
vfs_caches_init();
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();
proc_root_init();
nsfs_init();
cpuset_init();
cgroup_init();
taskstats_init_early();
delayacct_init();
check_bugs();
acpi_subsystem_init();
sfi_init_late();
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_late_init();
efi_free_boot_services();
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);
#ifdef CONFIG_KALLSYMS
struct blacklist_entry
struct list_head next;
char *buf;
;
static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
static int __init initcall_blacklist(char *str)
char *str_entry;
struct blacklist_entry *entry;
/* str argument is a comma-separated list of functions */
do
str_entry = strsep(&str, ",");
if (str_entry)
pr_debug("blacklisting initcall %s\\n", str_entry);
entry = alloc_bootmem(sizeof(*entry));
entry->buf = alloc_bootmem(strlen(str_entry) + 1);
strcpy(entry->buf, str_entry);
list_add(&entry->next, &blacklisted_initcalls);
while (str_entry);
return 0;
static bool __init_or_module initcall_blacklisted(initcall_t fn)
struct blacklist_entry *entry;
char fn_name[KSYM_SYMBOL_LEN];
unsigned long addr;
if (list_empty(&blacklisted_initcalls))
return false;
addr = (unsigned long) dereference_function_descriptor(fn);
sprint_symbol_no_offset(fn_name, addr);
/*
* fn will be "function_name [module_name]" where [module_name] is not
* displayed for built-in init functions. Strip off the [module_name].
*/
strreplace(fn_name, ' ', '\\0');
list_for_each_entry(entry, &blacklisted_initcalls, next)
if (!strcmp(fn_name, entry->buf))
pr_debug("initcall %s blacklisted\\n", fn_name);
return true;
return false;
#else
static int __init initcall_blacklist(char *str)
pr_warn("initcall_blacklist requires CONFIG_KALLSYMS\\n");
return 0;
static bool __init_or_module initcall_blacklisted(initcall_t fn)
return false;
#endif
__setup("initcall_blacklist=", initcall_blacklist);
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\\n", 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\\n",
fn, ret, duration);
return ret;
int __init_or_module do_one_initcall(initcall_t fn)
int count = preempt_count();
int ret;
char msgbuf[64];
if (initcall_blacklisted(fn))
return -EPERM;
if (initcall_debug)
ret = do_one_initcall_debug(fn);
else
ret = fn();
msgbuf[0] = 0;
if (preempt_count() != count)
sprintf(msgbuf, "preemption imbalance ");
preempt_count_set(count);
if (irqs_disabled())
strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
local_irq_enable();
WARN(msgbuf[0], "initcall %pF returned with %s\\n", fn, msgbuf);
add_latent_entropy();
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,
;
/* Keep these in sync with initcalls in include/linux/init.h */
static char *initcall_level_names[] __initdata =
"early",
"core",
"postcore",
"arch",
"subsys",
"fs",
"device",
"late",
;
static void __init do_initcall_level(int level)
initcall_t *fn;
strcpy(initcall_command_line, saved_command_line);
parse_args(initcall_level_names[level],
initcall_command_line, __start___param,
__stop___param - __start___param,
level, level,
NULL, &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();
shmem_init();
driver_init();
init_irq_proc();
do_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);
/*
* This function requests modules which should be loaded by default and is
* called twice right after initrd is mounted and right before init is
* exec'd. If such modules are on either initrd or rootfs, they will be
* loaded before control is passed to userland.
*/
void __init load_default_modules(void)
load_default_elevator_module();
static int run_init_process(const char *init_filename)
argv_init[0] = init_filename;
return do_execve(getname_kernel(init_filename),
(const char __user *const __user *)argv_init,
(const char __user *const __user *)envp_init);
static int try_to_run_init_process(const char *init_filename)
int ret;
ret = run_init_process(init_filename);
if (ret && ret != -ENOENT)
pr_err("Starting init: %s exists but couldn't execute it (error %d)\\n",
init_filename, ret);
return ret;
static noinline void __init kernel_init_freeable(void);
#ifdef CONFIG_DEBUG_RODATA
static bool rodata_enabled = true;
static int __init set_debug_rodata(char *str)
return strtobool(str, &rodata_enabled);
__setup("rodata=", set_debug_rodata);
static void mark_readonly(void)
if (rodata_enabled)
mark_rodata_ro();
else
pr_info("Kernel memory protection disabled.\\n");
#else
static inline void mark_readonly(void)
pr_warn("This architecture does not have kernel memory protection.\\n");
#endif
static int __ref kernel_init(void *unused)
int ret;
kernel_init_freeable();
/* need to finish all async __init code before freeing the memory */
async_synchronize_full();
free_initmem();
mark_readonly();
system_state = SYSTEM_RUNNING;
numa_default_policy();
flush_delayed_fput();
rcu_end_inkernel_boot();
if (ramdisk_execute_command)
ret = run_init_process(ramdisk_execute_command);
if (!ret)
return 0;
pr_err("Failed to execute %s (error %d)\\n",
ramdisk_execute_command, ret);
/*
* 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.
*/
if (execute_command)
ret = run_init_process(execute_command);
if (!ret)
return 0;
panic("Requested init %s failed (error %d).",
execute_command, ret);
if (!try_to_run_init_process("/sbin/init") ||
!try_to_run_init_process("/etc/init") ||
!try_to_run_init_process("/bin/init") ||
!try_to_run_init_process("/bin/sh"))
return 0;
panic("No working init found. Try passing init= option to kernel. "
"See Linux Documentation/init.txt for guidance.");
static noinline void __init kernel_init_freeable(void)
/*
* Wait until kthreadd is all set-up.
*/
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_MEMORY]);
/*
* init can run on any cpu.
*/
set_cpus_allowed_ptr(current, cpu_all_mask);
cad_pid = task_pid(current);
smp_prepare_cpus(setup_max_cpus);
do_pre_smp_initcalls();
lockup_detector_init();
smp_init();
sched_init_smp();
page_alloc_init_late();
do_basic_setup();
/* Open the /dev/console on the rootfs, this should never fail */
if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
pr_err("Warning: unable to open an initial console.\\n");
(void) sys_dup(0);
(void) sys_dup(0);
/*
* check if there is an early userspace init. If yes, let it do all
* the work
*/
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..
*
* rootfs is available now, try loading the public keys
* and default modules
*/
integrity_load_keys();
load_default_modules();
下面是微软Visual Studio默认风格，格式化后1087行
/*
* 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 <grif@acm.org>
*/
#define DEBUG /* Enable initcall_debug */
#include <linux/types.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/stackprotector.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/bootmem.h>
#include <linux/acpi.h>
#include <linux/tty.h>
#include <linux/percpu.h>
#include <linux/kmod.h>
#include <linux/vmalloc.h>
#include <linux/kernel_stat.h>
#include <linux/start_kernel.h>
#include <linux/security.h>
#include <linux/smp.h>
#include <linux/profile.h>
#include <linux/rcupdate.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/writeback.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/cgroup.h>
#include <linux/efi.h>
#include <linux/tick.h>
#include <linux/interrupt.h>
#include <linux/taskstats_kern.h>
#include <linux/delayacct.h>
#include <linux/unistd.h>
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>
#include <linux/buffer_head.h>
#include <linux/page_ext.h>
#include <linux/debug_locks.h>
#include <linux/debugobjects.h>
#include <linux/lockdep.h>
#include <linux/kmemleak.h>
#include <linux/pid_namespace.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/idr.h>
#include <linux/kgdb.h>
#include <linux/ftrace.h>
#include <linux/async.h>
#include <linux/kmemcheck.h>
#include <linux/sfi.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/perf_event.h>
#include <linux/file.h>
#include <linux/ptrace.h>
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/sched_clock.h>
#include <linux/context_tracking.h>
#include <linux/random.h>
#include <linux/list.h>
#include <linux/integrity.h>
#include <linux/proc_ns.h>
#include <linux/io.h>
#include <asm/io.h>
#include <asm/bugs.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
static int kernel_init(void *);
extern void init_IRQ(void);
extern void fork_init(void);
extern void radix_tree_init(void);
/*
* 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);
/* 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;
/* Command line for per-initcall parameter parsing */
static char *initcall_command_line;
static char *execute_command;
static char *ramdisk_execute_command;
/*
* Used to generate warnings if static_key manipulation functions are used
* before jump_label_init is called.
*/
bool static_key_initialized __read_mostly;
EXPORT_SYMBOL_GPL(static_key_initialized);
/*
* 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 situation 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 bool __init obsolete_checksetup(char *line)
const struct obs_kernel_param *p;
bool had_early_param = false;
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 = true;
else if (!p->setup_func)
pr_warn("Parameter %s is obsolete, ignored\\n",
p->str);
return true;
else if (p->setup_func(line + n))
return true;
p++;
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