Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  1 /*
  2  *  linux/init/main.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  *
  6  *  GK 2/5/95  -  Changed to support mounting root fs via NFS
  7  *  Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
  8  *  Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
  9  *  Simplified starting of init:  Michael A. Griffith <grif@acm.org> 
 10  */
 11 
 12 #include <linux/types.h>
 13 #include <linux/module.h>
 14 #include <linux/proc_fs.h>
 15 #include <linux/kernel.h>
 16 #include <linux/syscalls.h>
 17 #include <linux/string.h>
 18 #include <linux/ctype.h>
 19 #include <linux/delay.h>
 20 #include <linux/utsname.h>
 21 #include <linux/ioport.h>
 22 #include <linux/init.h>
 23 #include <linux/smp_lock.h>
 24 #include <linux/initrd.h>
 25 #include <linux/hdreg.h>
 26 #include <linux/bootmem.h>
 27 #include <linux/tty.h>
 28 #include <linux/gfp.h>
 29 #include <linux/percpu.h>
 30 #include <linux/kmod.h>
 31 #include <linux/kernel_stat.h>
 32 #include <linux/start_kernel.h>
 33 #include <linux/security.h>
 34 #include <linux/workqueue.h>
 35 #include <linux/profile.h>
 36 #include <linux/rcupdate.h>
 37 #include <linux/posix-timers.h>
 38 #include <linux/moduleparam.h>
 39 #include <linux/kallsyms.h>
 40 #include <linux/writeback.h>
 41 #include <linux/cpu.h>
 42 #include <linux/cpuset.h>
 43 #include <linux/cgroup.h>
 44 #include <linux/efi.h>
 45 #include <linux/tick.h>
 46 #include <linux/interrupt.h>
 47 #include <linux/taskstats_kern.h>
 48 #include <linux/delayacct.h>
 49 #include <linux/unistd.h>
 50 #include <linux/rmap.h>
 51 #include <linux/irq.h>
 52 #include <linux/mempolicy.h>
 53 #include <linux/key.h>
 54 #include <linux/unwind.h>
 55 #include <linux/buffer_head.h>
 56 #include <linux/debug_locks.h>
 57 #include <linux/lockdep.h>
 58 #include <linux/pid_namespace.h>
 59 #include <linux/device.h>
 60 #include <linux/kthread.h>
 61 #include <linux/sched.h>
 62 #include <linux/signal.h>
 63 #include <linux/ftrace.h>
 64 
 65 #include <asm/io.h>
 66 #include <asm/bugs.h>
 67 #include <asm/setup.h>
 68 #include <asm/sections.h>
 69 #include <asm/cacheflush.h>
 70 
 71 #ifdef CONFIG_X86_LOCAL_APIC
 72 #include <asm/smp.h>
 73 #endif
 74 
 75 /*
 76  * This is one of the first .c files built. Error out early if we have compiler
 77  * trouble.
 78  */
 79 
 80 #if __GNUC__ == 4 && __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ == 0
 81 #warning gcc-4.1.0 is known to miscompile the kernel.  A different compiler version is recommended.
 82 #endif
 83 
 84 static int kernel_init(void *);
 85 
 86 extern void init_IRQ(void);
 87 extern void fork_init(unsigned long);
 88 extern void mca_init(void);
 89 extern void sbus_init(void);
 90 extern void pidhash_init(void);
 91 extern void pidmap_init(void);
 92 extern void prio_tree_init(void);
 93 extern void radix_tree_init(void);
 94 extern void free_initmem(void);
 95 #ifdef  CONFIG_ACPI
 96 extern void acpi_early_init(void);
 97 #else
 98 static inline void acpi_early_init(void) { }
 99 #endif
100 #ifndef CONFIG_DEBUG_RODATA
101 static inline void mark_rodata_ro(void) { }
102 #endif
103 #ifdef CONFIG_ALLOC_RTSJ_MEM
104 extern void alloc_rtsj_mem_early_setup(void);
105 #else
106 static inline void alloc_rtsj_mem_early_setup(void) { }
107 #endif
108 
109 
110 #ifdef CONFIG_TC
111 extern void tc_init(void);
112 #endif
113 
114 enum system_states system_state;
115 EXPORT_SYMBOL(system_state);
116 
117 /*
118  * Boot command-line arguments
119  */
120 #define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
121 #define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
122 
123 extern void time_init(void);
124 /* Default late time init is NULL. archs can override this later. */
125 void (*late_time_init)(void);
126 extern void softirq_init(void);
127 
128 /* Untouched command line saved by arch-specific code. */
129 char __initdata boot_command_line[COMMAND_LINE_SIZE];
130 /* Untouched saved command line (eg. for /proc) */
131 char *saved_command_line;
132 /* Command line for parameter parsing */
133 static char *static_command_line;
134 
135 static char *execute_command;
136 static char *ramdisk_execute_command;
137 
138 #ifdef CONFIG_SMP
139 /* Setup configured maximum number of CPUs to activate */
140 unsigned int __initdata setup_max_cpus = NR_CPUS;
141 
142 /*
143  * Setup routine for controlling SMP activation
144  *
145  * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
146  * activation entirely (the MPS table probe still happens, though).
147  *
148  * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
149  * greater than 0, limits the maximum number of CPUs activated in
150  * SMP mode to <NUM>.
151  */
152 #ifndef CONFIG_X86_IO_APIC
153 static inline void disable_ioapic_setup(void) {};
154 #endif
155 
156 static int __init nosmp(char *str)
157 {
158         setup_max_cpus = 0;
159         disable_ioapic_setup();
160         return 0;
161 }
162 
163 early_param("nosmp", nosmp);
164 
165 static int __init maxcpus(char *str)
166 {
167         get_option(&str, &setup_max_cpus);
168         if (setup_max_cpus == 0)
169                 disable_ioapic_setup();
170 
171         return 0;
172 }
173 
174 early_param("maxcpus", maxcpus);
175 #else
176 #define setup_max_cpus NR_CPUS
177 #endif
178 
179 /*
180  * If set, this is an indication to the drivers that reset the underlying
181  * device before going ahead with the initialization otherwise driver might
182  * rely on the BIOS and skip the reset operation.
183  *
184  * This is useful if kernel is booting in an unreliable environment.
185  * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
186  * skipped and devices will be in unknown state.
187  */
188 unsigned int reset_devices;
189 EXPORT_SYMBOL(reset_devices);
190 
191 static int __init set_reset_devices(char *str)
192 {
193         reset_devices = 1;
194         return 1;
195 }
196 
197 __setup("reset_devices", set_reset_devices);
198 
199 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
200 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
201 static const char *panic_later, *panic_param;
202 
203 extern struct obs_kernel_param __setup_start[], __setup_end[];
204 
205 static int __init obsolete_checksetup(char *line)
206 {
207         struct obs_kernel_param *p;
208         int had_early_param = 0;
209 
210         p = __setup_start;
211         do {
212                 int n = strlen(p->str);
213                 if (!strncmp(line, p->str, n)) {
214                         if (p->early) {
215                                 /* Already done in parse_early_param?
216                                  * (Needs exact match on param part).
217                                  * Keep iterating, as we can have early
218                                  * params and __setups of same names 8( */
219                                 if (line[n] == '\0' || line[n] == '=')
220                                         had_early_param = 1;
221                         } else if (!p->setup_func) {
222                                 printk(KERN_WARNING "Parameter %s is obsolete,"
223                                        " ignored\n", p->str);
224                                 return 1;
225                         } else if (p->setup_func(line + n))
226                                 return 1;
227                 }
228                 p++;
229         } while (p < __setup_end);
230 
231         return had_early_param;
232 }
233 
234 /*
235  * This should be approx 2 Bo*oMips to start (note initial shift), and will
236  * still work even if initially too large, it will just take slightly longer
237  */
238 unsigned long loops_per_jiffy = (1<<12);
239 
240 EXPORT_SYMBOL(loops_per_jiffy);
241 
242 static int __init debug_kernel(char *str)
243 {
244         console_loglevel = 10;
245         return 0;
246 }
247 
248 static int __init quiet_kernel(char *str)
249 {
250         console_loglevel = 4;
251         return 0;
252 }
253 
254 early_param("debug", debug_kernel);
255 early_param("quiet", quiet_kernel);
256 
257 static int __init loglevel(char *str)
258 {
259         get_option(&str, &console_loglevel);
260         return 0;
261 }
262 
263 early_param("loglevel", loglevel);
264 
265 /*
266  * Unknown boot options get handed to init, unless they look like
267  * failed parameters
268  */
269 static int __init unknown_bootoption(char *param, char *val)
270 {
271         /* Change NUL term back to "=", to make "param" the whole string. */
272         if (val) {
273                 /* param=val or param="val"? */
274                 if (val == param+strlen(param)+1)
275                         val[-1] = '=';
276                 else if (val == param+strlen(param)+2) {
277                         val[-2] = '=';
278                         memmove(val-1, val, strlen(val)+1);
279                         val--;
280                 } else
281                         BUG();
282         }
283 
284         /* Handle obsolete-style parameters */
285         if (obsolete_checksetup(param))
286                 return 0;
287 
288         /*
289          * Preemptive maintenance for "why didn't my misspelled command
290          * line work?"
291          */
292         if (strchr(param, '.') && (!val || strchr(param, '.') < val)) {
293                 printk(KERN_ERR "Unknown boot option `%s': ignoring\n", param);
294                 return 0;
295         }
296 
297         if (panic_later)
298                 return 0;
299 
300         if (val) {
301                 /* Environment option */
302                 unsigned int i;
303                 for (i = 0; envp_init[i]; i++) {
304                         if (i == MAX_INIT_ENVS) {
305                                 panic_later = "Too many boot env vars at `%s'";
306                                 panic_param = param;
307                         }
308                         if (!strncmp(param, envp_init[i], val - param))
309                                 break;
310                 }
311                 envp_init[i] = param;
312         } else {
313                 /* Command line option */
314                 unsigned int i;
315                 for (i = 0; argv_init[i]; i++) {
316                         if (i == MAX_INIT_ARGS) {
317                                 panic_later = "Too many boot init vars at `%s'";
318                                 panic_param = param;
319                         }
320                 }
321                 argv_init[i] = param;
322         }
323         return 0;
324 }
325 
326 #ifdef CONFIG_DEBUG_PAGEALLOC
327 int __read_mostly debug_pagealloc_enabled = 0;
328 #endif
329 
330 static int __init init_setup(char *str)
331 {
332         unsigned int i;
333 
334         execute_command = str;
335         /*
336          * In case LILO is going to boot us with default command line,
337          * it prepends "auto" before the whole cmdline which makes
338          * the shell think it should execute a script with such name.
339          * So we ignore all arguments entered _before_ init=... [MJ]
340          */
341         for (i = 1; i < MAX_INIT_ARGS; i++)
342                 argv_init[i] = NULL;
343         return 1;
344 }
345 __setup("init=", init_setup);
346 
347 static int __init rdinit_setup(char *str)
348 {
349         unsigned int i;
350 
351         ramdisk_execute_command = str;
352         /* See "auto" comment in init_setup */
353         for (i = 1; i < MAX_INIT_ARGS; i++)
354                 argv_init[i] = NULL;
355         return 1;
356 }
357 __setup("rdinit=", rdinit_setup);
358 
359 #ifndef CONFIG_SMP
360 
361 #ifdef CONFIG_X86_LOCAL_APIC
362 static void __init smp_init(void)
363 {
364         APIC_init_uniprocessor();
365 }
366 #else
367 #define smp_init()      do { } while (0)
368 #endif
369 
370 static inline void setup_per_cpu_areas(void) { }
371 static inline void smp_prepare_cpus(unsigned int maxcpus) { }
372 
373 #else
374 
375 #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
376 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
377 
378 EXPORT_SYMBOL(__per_cpu_offset);
379 
380 static void __init setup_per_cpu_areas(void)
381 {
382         unsigned long size, i;
383         char *ptr;
384         unsigned long nr_possible_cpus = num_possible_cpus();
385 
386         /* Copy section for each CPU (we discard the original) */
387         size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
388         ptr = alloc_bootmem_pages(size * nr_possible_cpus);
389 
390         for_each_possible_cpu(i) {
391                 __per_cpu_offset[i] = ptr - __per_cpu_start;
392                 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
393                 ptr += size;
394         }
395 }
396 #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
397 
398 /* Called by boot processor to activate the rest. */
399 static void __init smp_init(void)
400 {
401         unsigned int cpu;
402 
403         /* FIXME: This should be done in userspace --RR */
404         for_each_present_cpu(cpu) {
405                 if (num_online_cpus() >= setup_max_cpus)
406                         break;
407                 if (!cpu_online(cpu))
408                         cpu_up(cpu);
409         }
410 
411         /* Any cleanup work */
412         printk(KERN_INFO "Brought up %ld CPUs\n", (long)num_online_cpus());
413         smp_cpus_done(setup_max_cpus);
414 }
415 
416 #endif
417 
418 /*
419  * We need to store the untouched command line for future reference.
420  * We also need to store the touched command line since the parameter
421  * parsing is performed in place, and we should allow a component to
422  * store reference of name/value for future reference.
423  */
424 static void __init setup_command_line(char *command_line)
425 {
426         saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
427         static_command_line = alloc_bootmem(strlen (command_line)+1);
428         strcpy (saved_command_line, boot_command_line);
429         strcpy (static_command_line, command_line);
430 }
431 
432 /*
433  * We need to finalize in a non-__init function or else race conditions
434  * between the root thread and the init thread may cause start_kernel to
435  * be reaped by free_initmem before the root thread has proceeded to
436  * cpu_idle.
437  *
438  * gcc-3.4 accidentally inlines this function, so use noinline.
439  */
440 
441 static void noinline __init_refok rest_init(void)
442         __releases(kernel_lock)
443 {
444         int pid;
445 
446         system_state = SYSTEM_BOOTING_SCHEDULER_OK;
447 
448         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
449         numa_default_policy();
450         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
451         kthreadd_task = find_task_by_pid(pid);
452         unlock_kernel();
453 
454         /*
455          * The boot idle thread must execute schedule()
456          * at least once to get things moving:
457          */
458         init_idle_bootup_task(current);
459         __preempt_enable_no_resched();
460         schedule();
461         preempt_disable();
462 
463         /* Call into cpu_idle with preempt disabled */
464         cpu_idle();
465 }
466 
467 /* Check for early params. */
468 static int __init do_early_param(char *param, char *val)
469 {
470         struct obs_kernel_param *p;
471 
472         for (p = __setup_start; p < __setup_end; p++) {
473                 if ((p->early && strcmp(param, p->str) == 0) ||
474                     (strcmp(param, "console") == 0 &&
475                      strcmp(p->str, "earlycon") == 0)
476                 ) {
477                         if (p->setup_func(val) != 0)
478                                 printk(KERN_WARNING
479                                        "Malformed early option '%s'\n", param);
480                 }
481         }
482         /* We accept everything at this stage. */
483         return 0;
484 }
485 
486 /* Arch code calls this early on, or if not, just before other parsing. */
487 void __init parse_early_param(void)
488 {
489         static __initdata int done = 0;
490         static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
491 
492         if (done)
493                 return;
494 
495         /* All fall through to do_early_param. */
496         strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
497         parse_args("early options", tmp_cmdline, NULL, 0, do_early_param);
498         done = 1;
499 }
500 
501 /*
502  *      Activate the first processor.
503  */
504 
505 static void __init boot_cpu_init(void)
506 {
507         int cpu = smp_processor_id();
508         /* Mark the boot cpu "present", "online" etc for SMP and UP case */
509         cpu_set(cpu, cpu_online_map);
510         cpu_set(cpu, cpu_present_map);
511         cpu_set(cpu, cpu_possible_map);
512 }
513 
514 void __init __attribute__((weak)) smp_setup_processor_id(void)
515 {
516 }
517 
518 asmlinkage void __init start_kernel(void)
519 {
520         char * command_line;
521         extern struct kernel_param __start___param[], __stop___param[];
522 
523         smp_setup_processor_id();
524 
525         /*
526          * Need to run as early as possible, to initialize the
527          * lockdep hash:
528          */
529         unwind_init();
530         lockdep_init();
531         cgroup_init_early();
532 
533         local_irq_disable();
534         early_boot_irqs_off();
535         early_init_irq_lock_class();
536 
537 /*
538  * Interrupts are still disabled. Do necessary setups, then
539  * enable them
540  */
541         lock_kernel();
542         tick_init();
543         boot_cpu_init();
544         page_address_init();
545         printk(KERN_NOTICE);
546         printk(linux_banner);
547         setup_arch(&command_line);
548         setup_command_line(command_line);
549         unwind_setup();
550         setup_per_cpu_areas();
551         smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
552 
553         /*
554          * Set up the scheduler prior starting any interrupts (such as the
555          * timer interrupt). Full topology setup happens at smp_init()
556          * time - but meanwhile we still have a functioning scheduler.
557          */
558         sched_init();
559         /*
560          * Disable preemption - early bootup scheduling is extremely
561          * fragile until we cpu_idle() for the first time.
562          */
563         preempt_disable();
564 
565         build_all_zonelists();
566         page_alloc_init();
567         early_init_hardirqs();
568         printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
569         parse_early_param();
570         parse_args("Booting kernel", static_command_line, __start___param,
571                    __stop___param - __start___param,
572                    &unknown_bootoption);
573         if (!irqs_disabled()) {
574                 printk(KERN_WARNING "start_kernel(): bug: interrupts were "
575                                 "enabled *very* early, fixing it\n");
576                 local_irq_disable();
577         }
578         sort_main_extable();
579         trap_init();
580         rcu_init();
581         init_IRQ();
582         pidhash_init();
583         init_timers();
584         hrtimers_init();
585         softirq_init();
586         timekeeping_init();
587         time_init();
588         sched_clock_init();
589         profile_init();
590         if (!irqs_disabled())
591                 printk("start_kernel(): bug: interrupts were enabled early\n");
592         early_boot_irqs_on();
593         local_irq_enable();
594 
595         /*
596          * HACK ALERT! This is early. We're enabling the console before
597          * we've done PCI setups etc, and console_init() must be aware of
598          * this. But we do want output early, in case something goes wrong.
599          */
600         console_init();
601         if (panic_later)
602                 panic(panic_later, panic_param);
603 
604         lockdep_info();
605 
606         /*
607          * Need to run this when irqs are enabled, because it wants
608          * to self-test [hard/soft]-irqs on/off lock inversion bugs
609          * too:
610          */
611         locking_selftest();
612 
613 #ifdef CONFIG_BLK_DEV_INITRD
614         if (initrd_start && !initrd_below_start_ok &&
615                         initrd_start < min_low_pfn << PAGE_SHIFT) {
616                 printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
617                     "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT);
618                 initrd_start = 0;
619         }
620 #endif
621         vfs_caches_init_early();
622         cpuset_init_early();
623         alloc_rtsj_mem_early_setup();
624         mem_init();
625         enable_debug_pagealloc();
626         cpu_hotplug_init();
627         kmem_cache_init();
628         setup_per_cpu_pageset();
629         numa_policy_init();
630         if (late_time_init)
631                 late_time_init();
632         calibrate_delay();
633         pidmap_init();
634         pgtable_cache_init();
635         prio_tree_init();
636         anon_vma_init();
637 #ifdef CONFIG_X86
638         if (efi_enabled)
639                 efi_enter_virtual_mode();
640 #endif
641         fork_init(num_physpages);
642         proc_caches_init();
643         buffer_init();
644         unnamed_dev_init();
645         key_init();
646         security_init();
647         vfs_caches_init(num_physpages);
648         radix_tree_init();
649         signals_init();
650         /* rootfs populating might need page-writeback */
651         page_writeback_init();
652 #ifdef CONFIG_PROC_FS
653         proc_root_init();
654 #endif
655         cgroup_init();
656         cpuset_init();
657         taskstats_init_early();
658         delayacct_init();
659 
660         check_bugs();
661 
662         acpi_early_init(); /* before LAPIC and SMP init */
663 
664 #ifdef CONFIG_PREEMPT_RT
665         WARN_ON(irqs_disabled());
666 #endif
667         /* Do the rest non-__init'ed, we're now alive */
668         rest_init();
669 }
670 
671 static int __initdata initcall_debug;
672 
673 static int __init initcall_debug_setup(char *str)
674 {
675         initcall_debug = 1;
676         return 1;
677 }
678 __setup("initcall_debug", initcall_debug_setup);
679 
680 extern initcall_t __initcall_start[], __initcall_end[];
681 
682 static void __init do_initcalls(void)
683 {
684         initcall_t *call;
685         int count = preempt_count();
686 
687         for (call = __initcall_start; call < __initcall_end; call++) {
688                 ktime_t t0, t1, delta;
689                 char *msg = NULL;
690                 char msgbuf[40];
691                 int result;
692 
693                 if (initcall_debug) {
694                         printk("Calling initcall 0x%p", *call);
695                         print_fn_descriptor_symbol(": %s()",
696                                         (unsigned long) *call);
697                         printk("\n");
698                         t0 = ktime_get();
699                 }
700 
701                 result = (*call)();
702 
703                 if (initcall_debug) {
704                         t1 = ktime_get();
705                         delta = ktime_sub(t1, t0);
706 
707                         printk("initcall 0x%p", *call);
708                         print_fn_descriptor_symbol(": %s()",
709                                         (unsigned long) *call);
710                         printk(" returned %d.\n", result);
711 
712                         printk("initcall 0x%p ran for %Ld msecs: ",
713                                 *call, (unsigned long long)delta.tv64 >> 20);
714                         print_fn_descriptor_symbol("%s()\n",
715                                 (unsigned long) *call);
716                 }
717 
718                 if (result && result != -ENODEV && initcall_debug) {
719                         sprintf(msgbuf, "error code %d", result);
720                         msg = msgbuf;
721                 }
722                 if (preempt_count() != count) {
723                         msg = "preemption imbalance";
724                         preempt_count() = count;
725                 }
726                 if (irqs_disabled()) {
727                         msg = "disabled interrupts";
728                         local_irq_enable();
729                 }
730                 if (msg) {
731                         printk(KERN_WARNING "initcall at 0x%p", *call);
732                         print_fn_descriptor_symbol(": %s()",
733                                         (unsigned long) *call);
734                         printk(": returned with %s\n", msg);
735                 }
736         }
737 
738         /* Make sure there is no pending stuff from the initcall sequence */
739         flush_scheduled_work();
740 }
741 
742 /*
743  * Ok, the machine is now initialized. None of the devices
744  * have been touched yet, but the CPU subsystem is up and
745  * running, and memory and process management works.
746  *
747  * Now we can finally start doing some real work..
748  */
749 static void __init do_basic_setup(void)
750 {
751         /* drivers will send hotplug events */
752         init_workqueues();
753         usermodehelper_init();
754         driver_init();
755         init_irq_proc();
756         do_initcalls();
757 }
758 
759 static int __initdata nosoftlockup;
760 
761 static int __init nosoftlockup_setup(char *str)
762 {
763         nosoftlockup = 1;
764         return 1;
765 }
766 __setup("nosoftlockup", nosoftlockup_setup);
767 
768 static void __init do_pre_smp_initcalls(void)
769 {
770         extern int spawn_ksoftirqd(void);
771         extern int spawn_desched_task(void);
772 
773         migration_init();
774         posix_cpu_thread_init();
775         spawn_ksoftirqd();
776         if (!nosoftlockup)
777                 spawn_softlockup_task();
778         spawn_desched_task();
779 }
780 
781 static void run_init_process(char *init_filename)
782 {
783         argv_init[0] = init_filename;
784         kernel_execve(init_filename, argv_init, envp_init);
785 }
786 
787 /* This is a non __init function. Force it to be noinline otherwise gcc
788  * makes it inline to init() and it becomes part of init.text section
789  */
790 static int noinline init_post(void)
791 {
792         free_initmem();
793         unlock_kernel();
794         mark_rodata_ro();
795         system_state = SYSTEM_RUNNING;
796         numa_default_policy();
797 
798         if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
799                 printk(KERN_WARNING "Warning: unable to open an initial console.\n");
800 
801         (void) sys_dup(0);
802         (void) sys_dup(0);
803 
804 #ifdef CONFIG_PREEMPT_RT
805         ftrace_disable_daemon();
806 #endif
807         if (ramdisk_execute_command) {
808                 run_init_process(ramdisk_execute_command);
809                 printk(KERN_WARNING "Failed to execute %s\n",
810                                 ramdisk_execute_command);
811         }
812 #ifdef CONFIG_PREEMPT_RT
813         WARN_ON(irqs_disabled());
814 #endif
815 
816         /*
817          * We try each of these until one succeeds.
818          *
819          * The Bourne shell can be used instead of init if we are
820          * trying to recover a really broken machine.
821          */
822         if (execute_command) {
823                 run_init_process(execute_command);
824                 printk(KERN_WARNING "Failed to execute %s.  Attempting "
825                                         "defaults...\n", execute_command);
826         }
827         run_init_process("/sbin/init");
828         run_init_process("/etc/init");
829         run_init_process("/bin/init");
830         run_init_process("/bin/sh");
831 
832         panic("No init found.  Try passing init= option to kernel.");
833 }
834 
835 static int __init kernel_init(void * unused)
836 {
837         lock_kernel();
838         /*
839          * init can run on any cpu.
840          */
841         set_cpus_allowed(current, CPU_MASK_ALL);
842         /*
843          * Tell the world that we're going to be the grim
844          * reaper of innocent orphaned children.
845          *
846          * We don't want people to have to make incorrect
847          * assumptions about where in the task array this
848          * can be found.
849          */
850         init_pid_ns.child_reaper = current;
851 
852         cad_pid = task_pid(current);
853 
854         smp_prepare_cpus(setup_max_cpus);
855 
856         init_hardirqs();
857 
858         do_pre_smp_initcalls();
859 
860         smp_init();
861         sched_init_smp();
862 
863         cpuset_init_smp();
864 
865         do_basic_setup();
866 
867         /*
868          * check if there is an early userspace init.  If yes, let it do all
869          * the work
870          */
871 
872         if (!ramdisk_execute_command)
873                 ramdisk_execute_command = "/init";
874 
875         if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
876                 ramdisk_execute_command = NULL;
877                 prepare_namespace();
878         }
879 #ifdef CONFIG_PREEMPT_RT
880         WARN_ON(irqs_disabled());
881 #endif
882 
883 #define DEBUG_COUNT (defined(CONFIG_DEBUG_RT_MUTEXES) + defined(CONFIG_IRQSOFF_TRACER) + defined(CONFIG_PREEMPT_TRACER) + defined(CONFIG_FTRACE) + defined(CONFIG_WAKEUP_LATENCY_HIST) + defined(CONFIG_DEBUG_SLAB) + defined(CONFIG_DEBUG_PAGEALLOC) + defined(CONFIG_LOCKDEP))
884 
885 #if DEBUG_COUNT > 0
886         printk(KERN_ERR "*****************************************************************************\n");
887         printk(KERN_ERR "*                                                                           *\n");
888 #if DEBUG_COUNT == 1
889         printk(KERN_ERR "*  REMINDER, the following debugging option is turned on in your .config:   *\n");
890 #else
891         printk(KERN_ERR "*  REMINDER, the following debugging options are turned on in your .config: *\n");
892 #endif
893         printk(KERN_ERR "*                                                                           *\n");
894 #ifdef CONFIG_DEBUG_RT_MUTEXES
895         printk(KERN_ERR "*        CONFIG_DEBUG_RT_MUTEXES                                            *\n");
896 #endif
897 #ifdef CONFIG_IRQSOFF_TRACER
898         printk(KERN_ERR "*        CONFIG_IRQSOFF_TRACER                                              *\n");
899 #endif
900 #ifdef CONFIG_PREEMPT_TRACER
901         printk(KERN_ERR "*        CONFIG_PREEMPT_TRACER                                              *\n");
902 #endif
903 #ifdef CONFIG_FTRACE
904         printk(KERN_ERR "*        CONFIG_FTRACE                                                      *\n");
905 #endif
906 #ifdef CONFIG_WAKEUP_LATENCY_HIST
907         printk(KERN_ERR "*        CONFIG_WAKEUP_LATENCY_HIST                                         *\n");
908 #endif
909 #ifdef CONFIG_DEBUG_SLAB
910         printk(KERN_ERR "*        CONFIG_DEBUG_SLAB                                                  *\n");
911 #endif
912 #ifdef CONFIG_DEBUG_PAGEALLOC
913         printk(KERN_ERR "*        CONFIG_DEBUG_PAGEALLOC                                             *\n");
914 #endif
915 #ifdef CONFIG_LOCKDEP
916         printk(KERN_ERR "*        CONFIG_LOCKDEP                                                     *\n");
917 #endif
918         printk(KERN_ERR "*                                                                           *\n");
919 #if DEBUG_COUNT == 1
920         printk(KERN_ERR "*  it may increase runtime overhead and latencies.                          *\n");
921 #else
922         printk(KERN_ERR "*  they may increase runtime overhead and latencies.                        *\n");
923 #endif
924         printk(KERN_ERR "*                                                                           *\n");
925         printk(KERN_ERR "*****************************************************************************\n");
926 #endif
927         /*
928          * Ok, we have completed the initial bootup, and
929          * we're essentially up and running. Get rid of the
930          * initmem segments and start the user-mode stuff..
931          */
932         init_post();
933         WARN_ON(debug_direct_keyboard);
934 
935         return 0;
936 }
937 
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