Linux内核的最初部分代码是用汇编语言写的（文件是boot/bootsect.s)。(我的汇编水平有限,暂且不看），它首先把自身这部分代码移到绝对地址0x90000，把下面的2K代码从引导设备加载到地址0x90200上，内核的其余部分加载到地址0x10000处。在加载系统时显示“loading...”. 然后，程序控制权交给另一个实模式汇编程序（boot/Setup.S）。
接下来，此程序把整个系统从地址0x10000移到地址0x1000，进入保护模式。程序控制转给系统的其余部分即地址0x1000。
下一个步骤是系统内核的解压过程，这部分代码在地址0x1000（文件/Boot/head.S），该段程序初始化寄存器，然后执行decompress_kernel()，这个函数源于zBoot/inflate.c、zBoot/unzip.c和zBoot/misc.c三个文件
Loading ....[ bootsect.S ]
uncompress .....[ decompress_kernel() ]
main.c ---> start_kernel() 开始.
开始 printk(banner);
Linux version 2.2.6 (root@lance) (gcc version 2.7.2.3) (检查一下GCC 的版本号, 在/init/main.c 中如果gcc 的版本号不够,时不允许编译内核的)
#40 Sun Apr 18 17:44:20 CST 1999
调用init_time()打印出以下内容:
Detected 199908264 Hz processor.
然后运行 console_init() --> drivers/char/tty_io.c */
Console: colour VGA+ 80x25
运行一个循环,测量一下 MIPS – 据说是要用一个确定的机器指令周期来实现实时的延迟.
Calibrating delay loop... 199.48 BogoMIPS
初始化内存/* init_mem */
Memory: 63396k/65536k available (848k kernel code, 408k reserved, 856k data
, 28k
/** dquote_init() **/
VFS: Diskquotas version dquot_6.4.0 initialized
察看cpu 的类型(在2.2.14 以后听说增加了对多种cpu 的支持, 以后我可得用心看看,if I can find a bug of intel then ……)
CPU: Intel Pentium Pro stepping 09
初始或处理器与协处理器,对于比较老的处理器, linux 会用软件模拟协处理器?
Checking 386/387 coupling... OK, FPU using exception 16 error reporting.
检查治理的合法性
Checking 'hlt' instruction... OK.
POSIX conformance testing by UNIFIX
此后调用 linux_thread(init ,..,..,)(arch/i386/kernel/process.c)
创建一个运行 init 的进程.
进入了第二阶段用户模式 ( user_mode )End of start_kerne最后进入cpu_idle ( arch/i386/kernel/process.c )
第二部分 设备的初始化
对设备的初始化调用. init()--->do_basic_init()--+
pci_init() 对pci 设备的初始化( 在main.c文件中有这样一段 ifdef PCI …..需要看一下)下面打印出结果:
PCI: PCI BIOS revision 2.10 entry at 0xfd8d1
PCI: Using configuration type 1
PCI: Probing PCI hardware
对Socket的初始化,socket_init() (这里也许就是linux 的网络秘密所在吧,以后我的注意) -Linux NET4.0 for Linux 2.2
Based upon Swansea University Computer Society NET3.039
NET4: Unix domain sockets 1.0 for Linux NET4.0.
NET4: Linux TCP/IP 1.0 for NET4.0
IP Protocols: ICMP, UDP, TCP
Starting kswapd v 1.5 kswapd_setup()
调用 device_setup()
Detected PS/2 Mouse Port.
初始化 声卡
Sound initialization started
Sound initialization complete
初始化 软驱
Floppy drive(s): fd0 is 1.44M
FDC 0 is a National Semiconductor PC87306
SCSI 设备的初始化
(scsi0) found at PCI 13/0
(scsi0) Wide Channel, SCSI ID=7, 16/255 SCBs
(scsi0) Downloading sequencer code... 419 instructions downloaded
scsi0 : Adaptec AHA274x/284x/294x (EISA/VLB/PCI-Fast SCSI) 5.1.10/3.2.4
scsi : 1 host.
Vendor: SEAGATE Model: ST32155W Rev: 0596
ype: Direct-Access ANSI SCSI revision: 02
Detected scsi disk sda at scsi0, channel 0, id 0, lun 0
Vendor: SEAGATE Model: ST32155W Rev: 0596
Type: Direct-Access ANSI SCSI revision: 02
Detected scsi disk sdb at scsi0, channel 0, id 1, lun 0
scsi : detected 2 SCSI disks total.
(scsi0:0:0:0) Synchronous at 40.0 Mbyte/sec, offset 8.
SCSI device sda: hdwr sector= 512 bytes. Sectors= 4197405 [2049 MB] [2.0 GB ](scsi0:0:1:0) Synchronous at 40.0 Mbyte/sec, offset 8.
SCSI device sdb: hdwr sector= 512 bytes. Sectors= 4197405 [2049 MB] [2.0 GB]Partition check: sda: sda1 |
sdb: sdb1 sdb2 |
安装 文件系统 filesystem_setup()
安装设备驱动程序 mount_root()
VFS: Mounted root (ext2 filesystem) readonly.
Freeing unused kernel memory: 28k freed
Adding Swap: 66540k swap-space (priority -1)
Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996
SB 3.01 detected OK (220)
at 0x220 irq 5 dma 1
YM3812 and OPL-3 driver Copyright (C) by Hannu Savolainen, Rob Hooft 1993-1
996 at 0x388
NET4: AppleTalk 0.18 for Linux NET4.0
eth0: Intel EtherExpress Pro 10/100 at 0xf800, 00:A0:C9:49:2F:FF, IRQ 9.
Board assembly 645520-034, Physical connectors present: RJ45
Primary interface chip DP83840 PHY #1.
DP83840 specific setup, setting register 23 to 8462.
General self-test: passed.
Serial sub-system self-test: passed.
Internal registers self-test: passed.
ROM checksum self-test: passed (0x49caa8d6).
Receiver lock-up workaround activated.
NET4: AppleTalk 0.18 for Linux NET4.0
结束 do_basic_setup()
open("/dev/console", O_RDWR, 0)
开始执行 /sbin/init ( execv(...) )
内核就此启动完毕...