先列出框架，具体后继再来分析。
首先是lds文件，该文件设置了各个section在FLASH或RAM中的先后顺序。
位于~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/vmlinux.lds
另外一个名字相似的，~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/vmlinux.lds.S
...#undef mips
#define mips mips
OUTPUT_ARCH(mips)
ENTRY(kernel_entry)
PHDRS {
text PT_LOAD FLAGS(7); /* RWX */
note PT_NOTE FLAGS(4); /* R__ */
}
#ifdef CONFIG_32BIT
#ifdef CONFIG_CPU_LITTLE_ENDIAN
jiffies = jiffies_64;
#else
jiffies = jiffies_64 + 4;
#endif
#else
jiffies = jiffies_64;
#endif
SECTIONS
{...
表明入口地址为kernel_entry，该符号在：~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/head.S中定义
...NESTED(kernel_entry, 16, sp) # kernel entry point
kernel_entry_setup # cpu specific setup
setup_c0_status_pri
/* We might not get launched at the address the kernel is linked to,
so we jump there. */
PTR_LA t0, 0f
jr t0
0:
#ifdef CONFIG_MIPS_MT_SMTC
/*
* In SMTC kernel, "CLI" is thread-specific, in TCStatus.
* We still need to enable interrupts globally in Status,
* and clear EXL/ERL.
*
* TCContext is used to track interrupt levels under
* service in SMTC kernel. Clear for boot TC before
* allowing any interrupts.
*/
mtc0 zero, CP0_TCCONTEXT
mfc0 t0, CP0_STATUS
ori t0, t0, 0xff1f
xori t0, t0, 0x001e
mtc0 t0, CP0_STATUS
#endif /* CONFIG_MIPS_MT_SMTC */
PTR_LA t0, __bss_start # clear .bss
LONG_S zero, (t0)
PTR_LA t1, __bss_stop - LONGSIZE
1:
PTR_ADDIU t0, LONGSIZE
LONG_S zero, (t0)
bne t0, t1, 1b
LONG_S a0, fw_arg0 # firmware arguments
LONG_S a1, fw_arg1
LONG_S a2, fw_arg2
LONG_S a3, fw_arg3
MTC0 zero, CP0_CONTEXT # clear context register
PTR_LA $28, init_thread_union
/* Set the SP after an empty pt_regs. */
PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE
PTR_ADDU sp, $28
back_to_back_c0_hazard
set_saved_sp sp, t0, t1
PTR_SUBU sp, 4 * SZREG # init stack pointer
j start_kernel
END(kernel_entry)...
最终跳到kernel_entry中，该函数在~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/init/main.c中定义：
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:
*/
lockdep_init();
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_owner(&init_mm, &init_task);
mm_init_cpumask(&init_mm);
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
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();
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 (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
local_irq_disable();
idr_init_cache();
perf_event_init();
rcu_init();
tick_nohz_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
early_irq_init();
init_IRQ();
tick_init();
init_timers();
hrtimers_init();
softirq_init();
timekeeping_init();
time_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(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_cgroup_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();
#ifdef CONFIG_X86
if (efi_enabled(EFI_RUNTIME_SERVICES))
efi_enter_virtual_mode();
#endif
thread_info_cache_init();
cred_init();
fork_init(totalram_pages);
proc_caches_init();
buffer_init();
key_init();
security_init();
dbg_late_init();
vfs_caches_init(totalram_pages);
signals_init();
/* rootfs populating might need page-writeback */
page_writeback_init();
#ifdef CONFIG_PROC_FS
proc_root_init();
#endif
cgroup_init();
cpuset_init();
taskstats_init_early();
delayacct_init();
check_bugs();
acpi_early_init(); /* before LAPIC and SMP 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();
}
上面调用了两个IRQ初始化函数early_irq_init和init_IRQ，分别在~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/kernel/irq/irqdesc.c和~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/irq.c中。
early_irq_init函数
int __init early_irq_init(void)
{
int i, initcnt, node = first_online_node;
struct irq_desc *desc;
init_irq_default_affinity();
/* Let arch update nr_irqs and return the nr of preallocated irqs */
initcnt = arch_probe_nr_irqs();
printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d %d\n", NR_IRQS, nr_irqs, initcnt);
if (WARN_ON(nr_irqs > IRQ_BITMAP_BITS))
nr_irqs = IRQ_BITMAP_BITS;
if (WARN_ON(initcnt > IRQ_BITMAP_BITS))
initcnt = IRQ_BITMAP_BITS;
if (initcnt > nr_irqs)
nr_irqs = initcnt;
for (i = 0; i < initcnt; i++) {
desc = alloc_desc(i, node, NULL);
set_bit(i, allocated_irqs);
irq_insert_desc(i, desc);
}
return arch_early_irq_init();
}
init_IRQ函数
void __init init_IRQ(void)
{
int i;
#ifdef CONFIG_KGDB
if (kgdb_early_setup)
return;
#endif
for (i = 0; i < NR_IRQS; i++)
irq_set_noprobe(i);
arch_init_irq();
#ifdef CONFIG_KGDB
if (!kgdb_early_setup)
kgdb_early_setup = 1;
#endif
}
上面调用的arch_init_irq函数位于~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/ath79/irq.c中
arch_init_irq函数
static void __init ath79_misc_irq_init(void)
{
void __iomem *base = ath79_reset_base;
int i;
__raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_ENABLE);
__raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_STATUS);
if (soc_is_ar71xx() || soc_is_ar913x())
ath79_misc_irq_chip.irq_mask_ack = ar71xx_misc_irq_mask;
else if (soc_is_ar724x() ||
soc_is_ar933x() ||
soc_is_ar934x() ||
soc_is_qca953x() ||
soc_is_qca955x())
ath79_misc_irq_chip.irq_ack = ar724x_misc_irq_ack;
else
BUG();
for (i = ATH79_MISC_IRQ_BASE;
i < ATH79_MISC_IRQ_BASE + ATH79_MISC_IRQ_COUNT; i++) {
irq_set_chip_and_handler(i, &ath79_misc_irq_chip,
handle_level_irq);
}
irq_set_chained_handler(ATH79_CPU_IRQ(6), ath79_misc_irq_handler);
}
...
void __init arch_init_irq(void)
{
if (soc_is_ar71xx()) {
ath79_ip2_handler = ar71xx_ip2_handler;
ath79_ip3_handler = ar71xx_ip3_handler;
} else if (soc_is_ar724x()) {
ath79_ip2_handler = ar724x_ip2_handler;
ath79_ip3_handler = ar724x_ip3_handler;
} else if (soc_is_ar913x()) {
ath79_ip2_handler = ar913x_ip2_handler;
ath79_ip3_handler = ar913x_ip3_handler;
} else if (soc_is_ar933x()) {
ath79_ip2_handler = ar933x_ip2_handler;
ath79_ip3_handler = ar933x_ip3_handler;
} else if (soc_is_ar934x()) {
ath79_ip2_handler = ath79_default_ip2_handler;
ath79_ip3_handler = ar934x_ip3_handler;
} else if (soc_is_qca953x()) {
ath79_ip2_handler = ath79_default_ip2_handler;
ath79_ip3_handler = ath79_default_ip3_handler;
} else if (soc_is_qca955x()) {
ath79_ip2_handler = ath79_default_ip2_handler;
ath79_ip3_handler = ath79_default_ip3_handler;
} else {
BUG();
}
cp0_perfcount_irq = ATH79_MISC_IRQ(5);
mips_cpu_irq_init();
ath79_misc_irq_init();
if (soc_is_ar934x())
ar934x_ip2_irq_init();
else if (soc_is_qca955x())
qca955x_irq_init();
}
mips_cpu_irq_init函数位于~/openwrt1407/build_dir/target-mips_34kc_uClibc-0.9.33.2/linux-ar71xx_generic/linux-3.10.49/arch/mips/kernel/irq_cpu.c中，ath79_misc_irq_init同在irq.c文件中。
void __init mips_cpu_irq_init(void)
{
int irq_base = MIPS_CPU_IRQ_BASE;
int i;
/* Mask interrupts. */
clear_c0_status(ST0_IM);
clear_c0_cause(CAUSEF_IP);
/* Software interrupts are used for MT/CMT IPI */
for (i = irq_base; i < irq_base + 2; i++)
irq_set_chip_and_handler(i, cpu_has_mipsmt ?
&mips_mt_cpu_irq_controller :
&mips_cpu_irq_controller,
handle_percpu_irq);
for (i = irq_base + 2; i < irq_base + 8; i++)
irq_set_chip_and_handler(i, &mips_cpu_irq_controller,
handle_percpu_irq);
}
时间： 2025-01-18 07:36:37