执行setup_arch()函数

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5.2 执行setup_arch()函数

回到start_kernel当中，562行，调用setup_arch函数，传给他的参数是那个未被初始化的内部变量command_line。这个setup_arch()函数是start_kernel阶段最重要的一个函数，每个体系都有自己的setup_arch()函数，是体系结构相关的，具体编译哪个体系的setup_arch()函数，由顶层Makefile中的ARCH变量决定：

724void __init setup_arch(char **cmdline_p)

725{

726 int acpi = 0;

727 int k8 = 0;

728

……

730 memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));

731 visws_early_detect();

……

736 /* VMI may relocate the fixmap; do this before touching ioremap area */

737 vmi_init();

738

739 early_cpu_init();

740 early_ioremap_init();

741

742 ROOT_DEV = old_decode_dev(boot_params.hdr.root_dev);

743 screen_info = boot_params.screen_info;

744 edid_info = boot_params.edid_info;

……

746 apm_info.bios = boot_params.apm_bios_info;

747 ist_info = boot_params.ist_info;

748 if (boot_params.sys_desc_table.length != 0) {

749 set_mca_bus(boot_params.sys_desc_table.table[3] & 0x2);

750 machine_id = boot_params.sys_desc_table.table[0];

751 machine_submodel_id = boot_params.sys_desc_table.table[1];

752 BIOS_revision = boot_params.sys_desc_table.table[2];

753 }

……

755 saved_video_mode = boot_params.hdr.vid_mode;

756 bootloader_type = boot_params.hdr.type_of_loader;

757 if ((bootloader_type >> 4) == 0xe) {

758 bootloader_type &= 0xf;

759 bootloader_type |= (boot_params.hdr.ext_loader_type+0x10) << 4;

760 }

761 bootloader_version = bootloader_type & 0xf;

762 bootloader_version |= boot_params.hdr.ext_loader_ver << 4;

……

782 x86_init.oem.arch_setup();

783

784 setup_memory_map();

785 parse_setup_data();

786 /* update the e820_saved too */

787 e820_reserve_setup_data();

788

789 copy_edd();

790

791 if (!boot_params.hdr.root_flags)

792 root_mountflags &= ~MS_RDONLY;

793 init_mm.start_code = (unsigned long) _text;

794 init_mm.end_code = (unsigned long) _etext;

795 init_mm.end_data = (unsigned long) _edata;

796 init_mm.brk = _brk_end;

797

798 code_resource.start = virt_to_phys(_text);

799 code_resource.end = virt_to_phys(_etext)-1;

800 data_resource.start = virt_to_phys(_etext);

801 data_resource.end = virt_to_phys(_edata)-1;

802 bss_resource.start = virt_to_phys(&__bss_start);

803 bss_resource.end = virt_to_phys(&__bss_stop)-1;

……

817

818 strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);

819 *cmdline_p = command_line;

……

828 x86_configure_nx();

829

830 parse_early_param();

831

832 x86_report_nx();

833

834 /* Must be before kernel pagetables are setup */

835 vmi_activate();

836

837 /* after early param, so could get panic from serial */

838 reserve_early_setup_data();

839

840 if (acpi_mps_check()) {

841#ifdef CONFIG_X86_LOCAL_APIC

842 disable_apic = 1;

843#endif

844 setup_clear_cpu_cap(X86_FEATURE_APIC);

845 }

846

847#ifdef CONFIG_PCI

848 if (pci_early_dump_regs)

849 early_dump_pci_devices();

850#endif

851

852 finish_e820_parsing();

853

854 if (efi_enabled)

855 efi_init();

856

857 dmi_scan_machine();

858

859 dmi_check_system(bad_bios_dmi_table);

860

……

865 init_hypervisor_platform();

866

867 x86_init.resources.probe_roms();

868

869 /* after parse_early_param, so could debug it */

870 insert_resource(&iomem_resource, &code_resource);

871 insert_resource(&iomem_resource, &data_resource);

872 insert_resource(&iomem_resource, &bss_resource);

873

874 trim_bios_range();

……

891 max_pfn = e820_end_of_ram_pfn();

892

893 /* preallocate 4k for mptable mpc */

894 early_reserve_e820_mpc_new();

895 /* update e820 for memory not covered by WB MTRRs */

896 mtrr_bp_init();

897 if (mtrr_trim_uncached_memory(max_pfn))

898 max_pfn = e820_end_of_ram_pfn();

899

……

901 /* max_low_pfn get updated here */

902 find_low_pfn_range();

……

923 printk(KERN_DEBUG "initial memory mapped : 0 - %08lx/n",

924 max_pfn_mapped<<PAGE_SHIFT);

925

926 reserve_brk();

927

928 /*

929 * Find and reserve possible boot-time SMP configuration:

930 */

931 find_smp_config();

932

933 reserve_ibft_region();

934

935 reserve_trampoline_memory();

……

944 init_gbpages();

945

946 /* max_pfn_mapped is updated here */

947 max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);

948 max_pfn_mapped = max_low_pfn_mapped;

949

……

968 reserve_initrd();

969

970 reserve_crashkernel();

971

972 vsmp_init();

973

974 io_delay_init();

975

976 /*

977 * Parse the ACPI tables for possible boot-time SMP configuration.

978 */

979 acpi_boot_table_init();

980

981 early_acpi_boot_init();

982

983#ifdef CONFIG_ACPI_NUMA

984 /*

985 * Parse SRAT to discover nodes.

986 */

987 acpi = acpi_numa_init();

988#endif

989

990#ifdef CONFIG_K8_NUMA

991 if (!acpi)

992 k8 = !k8_numa_init(0, max_pfn);

993#endif

994

995 initmem_init(0, max_pfn, acpi, k8);

996#ifndef CONFIG_NO_BOOTMEM

997 early_res_to_bootmem(0, max_low_pfn<<PAGE_SHIFT);

998#endif

999

1000 dma32_reserve_bootmem();

……

1005

1006 x86_init.paging.pagetable_setup_start(swapper_pg_dir);

1007 paging_init();

1008 x86_init.paging.pagetable_setup_done(swapper_pg_dir);

1009

1010 tboot_probe();

1011

……

1016 generic_apic_probe();

1017

1018 early_quirks();

1019

1020 /*

1021 * Read APIC and some other early information from ACPI tables.

1022 */

1023 acpi_boot_init();

1024

1025 sfi_init();

1026

1027 /*

1028 * get boot-time SMP configuration:

1029 */

1030 if (smp_found_config)

1031 get_smp_config();

1032

1033 prefill_possible_map();

1034

……

1038

1039 init_apic_mappings();

1040 ioapic_init_mappings();

1041

1042 /* need to wait for io_apic is mapped */

1043 probe_nr_irqs_gsi();

1044

1045 kvm_guest_init();

1046

1047 e820_reserve_resources();

1048 e820_mark_nosave_regions(max_low_pfn);

1049

1050 x86_init.resources.reserve_resources();

1051

1052 e820_setup_gap();

1053

1054#ifdef CONFIG_VT

1055#if defined(CONFIG_VGA_CONSOLE)

1056 if (!efi_enabled || (efi_mem_type(0xa0000) != EFI_CONVENTIONAL_MEMORY))

1057 conswitchp = &vga_con;

1058#elif defined(CONFIG_DUMMY_CONSOLE)

1059 conswitchp = &dummy_con;

1060#endif

1061#endif

1062 x86_init.oem.banner();

1063

1064 mcheck_init();

1065}

浩浩荡荡300多行代码，我们去掉了其中64位x86体系的相关代码，以及一些未配置的编译选项，如CONFIG_EFI、CONFIG_CMDLINE_BOOL、CONFIG_ACPI_SLEEP等的相关代码，剩余对我们有用的代码如上所示，也有将近200行。我们这里只挑几个重要的来讲解一下，主要涉及初始化阶段的内存分配器的安装。