1、BootROM部分
在器件上電運行後，處理器自動開始Stage-0 Boot，也就是執行片內BootROM中的代碼
BootROM會初始化CPU和一些外設，以便讀取下一個啓動階段所需的程序代碼，FSBL（First
2、BOOT.bin部分
BootROM會去讀取MIO[2..8],從而確定啓動設備方式（Zynq支持多種啓動設備方式,可以使用跳線帽設置），將選定設備的頭192Kbyte內容，也就是FSBL，複製到OCM(On Chip Memory)中，並將控制器交給FSBL。
FSBL部分
FSBL啓動時可以使用整塊256Kb的OCM，當FSBL開始運行後，器件就正式由開發者或用戶控制了。Xilinx提供了一份FSBL代碼，如果沒什麼特殊要求，可以直接使用。
嵌入式系統系統啓動一般都是在 nor flash （NOR flash 可以直接運行程序，NAND flash需要將程序加載到內存運行，和 BIOS 很類似，nor flash 成本很高）。
BIOS是（Basic Input Output System）"基本輸入輸出系統"
它是一組固化到計算機內主板上一個ROM芯片上的程序，它保存着計算機最重要的基本輸入輸出的程序、開機後自檢程序和系統自啓動程序，它可從CMOS中讀寫系統設置的具體信息。 其主要功能是爲計算機提供最底層的、最直接的硬件設置和控制。
RAM（random access memory）即隨機存儲內存，這種存儲器在斷電時將丟失其存儲內容，故主要用於存儲短時間使用的程序。ROM（Read-Only Memory）即只讀內存，是一種只能讀出事先所存數據的固態半導體存儲器。
uboot 就是針對嵌入式環境特別編譯準備的一級引導程序。用來初始化環境，並且讀取啓動 Linux 內核的東西。
因爲在u-boot中配置從eMMC啓動，所以在u-boot之前會先初始化一些外設,配置PL端資源，如eMMC，下面爲初始化eMMC的打印信息。
Device: sdhci@e0100000
Manufacturer ID: fe
OEM: 14e
Name: MMC02
Tran Speed: 52000000
Rd Block Len: 512
MMC version 4.4.1
High Capacity: No
Capacity: 1.8 GiB
Bus Width: 4-bit
Erase Group Size: 512 KiB
HC WP Group Size: 0 Bytes
User Capacity: 1.8 GiB
Boot Capacity: 1 MiB ENH
RPMB Capacity: 128 KiB ENH
u-boot.elf從發eMMC加載image.ub到片上內存DDR3（2G）中
readingimage.ub
11274340 bytes read in 611 ms (17.6 MiB/s)
首先是加載Linux kernel，狀態爲尚未解壓，大小3.8MiB，使用了SHA1安全哈希算法（Secure Hash Algorithm）
## Loading kernel from FIT Image at10000000 ...
Using 'conf@1' configuration
Verifying Hash Integrity ... OK
Trying 'kernel@0' kernel subimage
Description: Linux Kernel
Type: Kernel Image
Compression: uncompressed
Data Start: 0x100000d4
Data Size: 4005144 Bytes = 3.8MiB
Architecture: ARM
OS: Linux
Load Address: 0x00008000
Entry Point: 0x00008000
Hash algo: sha1
Hash value: 3b953474750d8fb67e6a25dece81e156c4ecdcb2
Verifying Hash Integrity ... sha1+ OK
接着是加載ramdisk，狀態爲尚未解壓,大小6.9MiB，使用了SHA1安全哈希算法（Secure Hash Algorithm）
## Loading ramdisk from FIT Image at10000000 ...
Using 'conf@1' configuration
Trying 'ramdisk@0' ramdisk subimage
Description: ramdisk
Type: RAMDisk Image
Compression: uncompressed
Data Start: 0x103d686c
Data Size: 7248902 Bytes = 6.9MiB
Architecture: ARM
OS: Linux
Load Address: unavailable
Entry Point: unavailable
Hash algo: sha1
Hash value: e934ce35c9f408811fcb859dff09b0aed896871b
Verifying Hash Integrity ... sha1+ OK
最後是加載fdt（設備樹文件），狀態爲尚未解壓，大小18.2KiB，使用了SHA1安全哈希算法（Secure Hash Algorithm）
## Loading fdt from FIT Image at 10000000...
Using 'conf@1' configuration
Trying 'fdt@0' fdt subimage
Description: Flattened DeviceTree blob
Type: Flat Device Tree
Compression: uncompressed
Data Start: 0x103d1ee0
Data Size: 18649 Bytes = 18.2KiB
Architecture: ARM
Hash algo: sha1
Hash value: 97ab0c048f0da9de6329b48e1345c2aedc552995
Verifying Hash Integrity ... sha1+ OK
Booting using the fdt blob at 0x103d1ee0
Loading Kernel Image ... OK
Loading Ramdisk to 07916000, end 07fffc06... OK
Loading Device Tree to 0790e000, end079158d8 ... OK
引導加載完成，準備運行
解壓Linux內核鏡像並啓動Linux內核，運行在CPU0上
Starting kernel ...
Uncompressing Linux...done, booting the kernel.
Booting Linux on physical CPU0x0
Linux version 4.6.0-xilinx(bjut@virtua-ubuntu1604) (gcc version 5.2.1 20151005 (Linaro GCC 5.2-2015.11-2)) #1 SMP PREEMPT Mon Apr 24 15:03:20 CST 2017
CPU: ARMv7 Processor[413fc090] revision 0 (ARMv7), cr=18c5387d
CPU: PIPT / VIPTnonaliasing data cache, VIPT aliasing instruction cache
Machine model:huanbao_qspi_emmc
bootconsole [earlycon0]enabled
cma: Reserved 16 MiB at0x3f000000
Memory policy: Data cachewritealloc
percpu: Embedded 12pages/cpu @ef7d0000 s19776 r8192 d21184 u49152
Built 1 zonelists in Zoneorder, mobility grouping on. Totalpages: 260608
Kernel command line:console=ttyPS0,115200 earlyprintk
開始解壓文件系統鏡像
Trying to unpack rootfsimage as initramfs...
Freeing initrd memory:7080K (c7916000 - c8000000)
hw perfevents: enabledwith armv7_cortex_a9 PMU driver, 7 counters available
futex hash table entries:512 (order: 3, 32768 bytes)
workingset:timestamp_bits=28 max_order=18 bucket_order=0
jffs2: version 2.2. (NAND)(SUMMARY) 漏2001-2006 Red Hat, Inc.
bounce: pool size: 64pages
io scheduler noopregistered
io scheduler deadlineregistered
io scheduler cfqregistered (default)
dma-pl330 f8003000.dmac:Loaded driver for PL330 DMAC-241330
dma-pl330 f8003000.dmac: DBUFF-128x8bytes Num_Chans-8 Num_Peri-4Num_Events-16
42c00000.serial: ttyUL1 atMMIO 0x42c00000 (irq = 167, base_baud = 0) is a uartlite
42c10000.serial: ttyUL2 atMMIO 0x42c10000 (irq = 168, base_baud = 0) is a uartlite
42ca0000.serial: ttyUL3 atMMIO 0x42ca0000 (irq = 169, base_baud = 0) is a uartlite
42cb0000.serial: ttyUL4 atMMIO 0x42cb0000 (irq = 170, base_baud = 0) is a uartlite
42c20000.serial: ttyUL5 atMMIO 0x42c20000 (irq = 171, base_baud = 0) is a uartlite
42c30000.serial: ttyUL6 atMMIO 0x42c30000 (irq = 172, base_baud = 0) is a uartlite
42c40000.serial: ttyUL7 atMMIO 0x42c40000 (irq = 173, base_baud = 0) is a uartlite
42c50000.serial: ttyUL8 atMMIO 0x42c50000 (irq = 174, base_baud = 0) is a uartlite
42c60000.serial: ttyUL9 atMMIO 0x42c60000 (irq = 175, base_baud = 0) is a uartlite
42c70000.serial: ttyUL10at MMIO 0x42c70000 (irq = 176, base_baud = 0) is a uartlite
42c80000.serial: ttyUL11at MMIO 0x42c80000 (irq = 177, base_baud = 0) is a uartlite
42c90000.serial: ttyUL12at MMIO 0x42c90000 (irq = 178, base_baud = 0) is a uartlite
e0000000.serial: ttyPS1 atMMIO 0xe0000000 (irq = 145, base_baud = 3125000) is a xuartps
e0001000.serial: ttyPS0 atMMIO 0xe0001000 (irq = 146, base_baud = 3125000) is a xuartps
郼onsole [ttyPS0] enabled
console [ttyPS0] enabled
bootconsole [earlycon0]disabled
bootconsole [earlycon0]disabled
xdevcfg f8007000.devcfg:ioremap 0xf8007000 to f090c000
[drm] Initialized drm1.1.0 20060810
brd: module loaded
loop: module loaded
m25p80 spi0.0: n25q128a11(16384 Kbytes)
4 ofpart partitions foundon MTD device spi0.0
Creating 4 MTD partitionson "spi0.0":
0x000000000000-0x000000500000: "boot"
0x000000500000-0x000000520000: "bootenv"
0x000000520000-0x000000fa0000: "kernel"
0x000000fa0000-0x000001000000: "spare"
CAN device driverinterface
gpiod_set_value: invalidGPIO
libphy: MACB_mii_bus:probed
[Firmware Warn]:/amba/ethernet@e000b000/mdio/phy@7: Whitelisted compatible string. Pleaseremove
macb e000b000.etherneteth0: Cadence GEM rev 0x00020118 at 0xe000b000 irq 148 (00:0a:35:00:1e:53)
Marvell 88E1111e000b000.etherne:07: attached PHY driver [Marvell 88E1111](mii_bus:phy_addr=e000b000.etherne:07, irq=-1)
e1000e: Intel(R) PRO/1000Network Driver - 3.2.6-k
e1000e: Copyright(c) 1999- 2015 Intel Corporation.
//開始註冊驅動
PPP generic driver version2.4.2
PPP BSD Compression moduleregistered
PPP Deflate Compressionmodule registered
PPP MPPE Compressionmodule registered
NET: Registered protocolfamily 24
usbcore: registered newinterface driver asix
usbcore: registered newinterface driver ax88179_178a
usbcore: registered newinterface driver cdc_ether
usbcore: registered newinterface driver net1080
usbcore: registered newinterface driver cdc_subset
usbcore: registered newinterface driver zaurus
usbcore: registered newinterface driver cdc_ncm
usbcore: registered newinterface driver huawei_cdc_ncm
usbcore: registered newinterface driver cdc_mbim
ehci_hcd: USB 2.0'Enhanced' Host Controller (EHCI) Driver
ehci-pci: EHCI PCIplatform driver
ohci_hcd: USB 1.1 'Open'Host Controller (OHCI) Driver
ohci-pci: OHCI PCIplatform driver
ohci-platform: OHCIgeneric platform driver
uhci_hcd: USB UniversalHost Controller Interface driver
usbcore: registered newinterface driver cdc_acm
cdc_acm: USB AbstractControl Model driver for USB modems and ISDN adapters
usbcore: registered newinterface driver cdc_wdm
usbcore: registered newinterface driver usb-storage
usbcore: registered newinterface driver usbserial
usbcore: registered newinterface driver option
usbserial: USB Serialsupport registered for GSM modem (1-port)
e0002000.usb supply vbusnot found, using dummy regulator
ULPI transceivervendor/product ID 0x0424/0x0007
Found SMSC USB3320 ULPItransceiver.
ULPI integrity check:passed.
ci_hdrc ci_hdrc.0: EHCIHost Controller
ci_hdrc ci_hdrc.0: new USBbus registered, assigned bus number 1
ci_hdrc ci_hdrc.0: USB 2.0started, EHCI 1.00
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 1 portdetected
mousedev: PS/2 mousedevice common for all mice
i2c /dev entries driver
rtc-pcf8563 0-0051: chipfound, driver version 0.4.4
rtc-pcf8563 0-0051: rtccore: registered rtc-pcf8563 as rtc0
cdns-i2c e0004000.i2c: 400kHz mmio e0004000 irq 142
Driver for 1-wire Dallasnetwork protocol.
EDAC MC: ECC not enabled
Xilinx Zynq CpuIdle Driverstarted
sdhci: Secure Digital HostController Interface driver
sdhci: Copyright(c) PierreOssman
sdhci-pltfm: SDHCIplatform and OF driver helper
mmc0: SDHCI controller one0100000.sdhci [e0100000.sdhci] using DMA
ledtrig-cpu: registered toindicate activity on CPUs
usbcore: registered newinterface driver usbhid
usbhid: USB HID coredriver
NET: Registered protocolfamily 10
sit: IPv6 over IPv4tunneling driver
NET: Registered protocolfamily 17
can: controller areanetwork core (rev 20120528 abi 9)
NET: Registered protocolfamily 29
can: raw protocol (rev20120528)
can: broadcast managerprotocol (rev 20120528 t)
can: netlink gateway (rev20130117) max_hops=1
Registering SWP/SWPBemulation handler
rtc-pcf8563 0-0051:setting system clock to 2000-04-09 21:55:13 UTC (955317313)
ALSA device list:
No soundcards found.
mmc0: new high speed MMCcard at address 0001
Freeing unused kernelmemory: 1024K (c0a00000 - c0b00000)
mmcblk0: mmc0:0001 MMC02G1.79 GiB
INIT: mmcblk0boot0:mmc0:0001 MMC02G partition 1 1.00 MiB
version 2.88bootingmmcblk0boot1: mmc0:0001 MMC02G partition 2 1.00 MiB
mmcblk0rpmb: mmc0:0001MMC02G partition 3 128 KiB
mmcblk0: p1
usb 1-1: new high-speedUSB device number 2 using ci_hdrc
hub 1-1:1.0: USB hub found
hub 1-1:1.0: 4 portsdetected
EXT4-fs (mmcblk0rpmb):unable to read superblock
EXT4-fs (mmcblk0rpmb):unable to read superblock
EXT2-fs (mmcblk0rpmb):error: unable to read superblock
FAT-fs (mmcblk0rpmb):unable to read boot sector
EXT4-fs (mmcblk0rpmb):unable to read superblock
EXT4-fs (mmcblk0rpmb):unable to read superblock
EXT2-fs (mmcblk0rpmb):error: unable to read superblock
FAT-fs (mmcblk0rpmb):unable to read boot sector
FAT-fs (mmcblk0rpmb):unable to read boot sector
usb 1-1.1: new high-speedUSB device number 3 using ci_hdrc
mount: mounting/dev/mmcblk0rpmb on /run/media/mmcblk0rpmb failed: Input/output error
mount: mounting/dev/mmcblk0boot0 on /run/media/mmcblk0boot0 failed: Invalid argument
cdc_ether 1-1.1:2.0 usb0:register 'cdc_ether' at usb-ci_hdrc.0-1.1, CDC Ethernet Device,02:1e:10:1f:00:00
//檢測到4G模塊，啓動4G模塊
option 1-1.1:2.2: GSMmodem (1-port) converter detected
usb 1-1.1: GSM modem(1-port) converter now attached to ttyUSB0
option 1-1.1:2.3: GSMmodem (1-port) converter detected
mount: mounting/dev/mmcblk0boot1 on /run/media/mmcblk0boot1 failed: Invalid argument
usb 1-1.1: GSM modem(1-port) converter now attached to ttyUSB1
option 1-1.1:2.4: GSMmodem (1-port) converter detected
usb 1-1.1: GSM modem (1-port)converter now attached to ttyUSB2
option 1-1.1:2.5: GSMmodem (1-port) converter detected
usb 1-1.1: GSM modem(1-port) converter now attached to ttyUSB3
option 1-1.1:2.6: GSMmodem (1-port) converter detected
usb 1-1.1: GSM modem(1-port) converter now attached to ttyUSB4
/etc/mdev/mdev-mount.sh:line 28: [: /sys/block/mmcblk0/mmcblk0boot1: binary operator expected
mount: mounting/dev/mmcblk0 on /run/media/mmcblk0 failed: Device or resource busy
random: dd urandom readwith 5 bits of entropy available
Mon Apr 24 07:06:36 UTC2017
Starting internetsuperserver: inetd.
INIT: Entering runlevel: 5
//配置以太網接口，等待網口芯片啓動
Configuring networkinterfaces... IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
done.
// 啓動Dropbear並生成密鑰，Dropbear是一個相對較小的SSH服務器和客戶端(開源軟件)。
Starting Dropbear SSHserver: Generating key, this may take a while...
//公鑰，用公鑰加密數據就必須用私鑰解密，如果用私鑰加密也必須用公鑰解密。
Public key portion is:
ssh-rsaAAAAB3NzaC1yc2EAAAADAQABAAABAQCQWM1vqfFHlIPbduTWsKeX1iQI4HMwuDZ46GV4FgJbtAFG/+9inB9K42p4YR06RrdnPdkvv2cPAQ/srfbm/qgF5BoKGdE32JsLU4EP9ovBecA6xSe2C2yzJ3e1HQOIaHcSWf59QpxTPFUrw+GYHNR4N8WZj6V9XJ+w6/5NWWSTwICjgo2yizVEodjsPc0VChAqmC8EBUz2evgBBJGbzm3mxgHXzsoKD/kKSlw2dtGcPCvO7GSdxYE1hBtk6xb8a6zToVOAPIqZFCnWtfEKUSexUx60I72nZngOtwqZR+ILR6BBLZqpomwc0AONZtjAYRrdIqnVPR2y0irVNIz1JAPx
root@plnx_arm
Fingerprint: md5b4:d4:cf:bc:ad:c0:79:93:89:66:ce:4a:b0:93:a5:2c
dropbear.
//啓動PetaLinux成功
Start Hello PetaLinux.
//運行初始化腳本
run init.sh
//配置網絡、路由
config network
//啓動系統日誌
Starting syslogd/klogd:set board time
//啓動4G撥號程序，後臺運行
run LTEConnection &
done
open /dev/ttyUSB0 SUCCESS
ttyclear:
Starting tcf-agent: OK
PetaLinux 2016.4 plnx_arm/dev/ttyPS0
//網卡芯片啓動成功
macb e000b000.etherneteth0: link up (1000/Full)
IPv6:ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
//用戶登錄系統
plnx_arm login:
//查看系統網卡信息
ifconfig
eth0 Link encap:Ethernet HWaddr 00:0A:35:00:1E:53
inet addr:192.168.0.100 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr:fe80::20a:35ff:fe00:1e53%768720/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:60 errors:0 dropped:0overruns:0 frame:0
TX packets:10 errors:0 dropped:0overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:6671 (6.5 KiB) TX bytes:1206 (1.1 KiB)
Interrupt:148 Base address:0xb000
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1%768720/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:8 errors:0 dropped:0overruns:0 frame:0
TX packets:8 errors:0 dropped:0overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:488 (488.0 B) TX bytes:488 (488.0 B)
usb0 Link encap:Ethernet HWaddr 02:1E:10:1F:00:00
inet addr:10.81.49.191 Bcast:10.81.49.255 Mask:255.255.255.128
inet6 addr:fe80::1e:10ff:fe1f:0%768720/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:9 errors:0 dropped:0overruns:0 frame:0
TX packets:15 errors:0 dropped:0overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1040 (1.0 KiB) TX bytes:1802 (1.7 KiB)
//查看系統設備信息
root@plnx_arm:~# ls /dev
bus null tty21 tty59
console port tty22 tty6
cpu_dma_latency ppp tty23 tty60
full psaux tty24 tty61
i2c-0 ptmx tty25 tty62
initctl pts tty26 tty63
input ram0 tty27 tty7
kmsg ram1 tty28 tty8
log ram10 tty29 tty9
loop-control ram11 tty3 ttyPS0
loop0 ram12 tty30 ttyPS1
loop1 ram13 tty31 ttyUL1
loop2 ram14 tty32 ttyUL10
loop3 ram15 tty33 ttyUL11
loop4 ram2 tty34 ttyUL12
loop5 ram3 tty35 ttyUL2
loop6 ram4 tty36 ttyUL3
loop7 ram5 tty37 ttyUL4
mdev.seq ram6 tty38 ttyUL5
mem ram7 tty39 ttyUL6
memory_bandwidth ram8 tty4 ttyUL7
mmcblk0 ram9 tty40 ttyUL8
mmcblk0boot0 random tty41 ttyUL9
mmcblk0boot1 rtc0 tty42 ttyUSB0
mmcblk0p1 shm tty43 ttyUSB1
mmcblk0rpmb snd tty44 ttyUSB2
mtab tty tty45 ttyUSB3
mtd0 tty0 tty46 ttyUSB4
mtd0ro tty1 tty47 urandom
mtd1 tty10 tty48 usbmon0
mtd1ro tty11 tty49 usbmon1
mtd2 tty12 tty5 vcs
mtd2ro tty13 tty50 vcs1
mtd3 tty14 tty51 vcsa
mtd3ro tty15 tty52 vcsa1
mtdblock0 tty16 tty53 vga_arbiter
mtdblock1 tty17 tty54 watchdog
mtdblock2 tty18 tty55 watchdog0
mtdblock3 tty19 tty56 xdevcfg
network_latency tty2 tty57 zero
network_throughput tty20 tty58
//系統關機過程：
oot@plnx_arm:~# shutdown-h now
Broadcast message fromroot@plnx_arm (ttyPS0) (Fri Oct 20 11:28:20 2017):
The syste@J蛠going down for system halt NOW!
INIT: Switching to runlev
//改變系統runlevel,0表示關機
//向系統進程發送中斷信號
INIT: Sending processesthe TERM signal
//停止Dropbear SSH server
root@plnx_arm:~# StoppingDropbear SSH server: stopped /usr/sbin/dropbear (pid 1160)
dropbear.
//停止Linux系統
Stop Hello PetaLinux.
//停止系統日誌進程
Stopping syslogd/klogd:stopped syslogd (pid 1173)
stopped klogd (pid 1175)
done
Stopping tcf-agent:random: nonblocking pool is initialized
FAIL
//清空網絡接口的配置
Deconfiguring networkinterfaces... done.
Sending all processes theTERM signal...
//退出用戶登錄
logout
macb e000b000.etherneteth0: link down
Sending all processes theKILL signal...
//卸載遠程文件系統和本地文件系統
Unmounting remotefilesystems...
Deactivating swap...
Unmounting localfilesystems...
//系統關機完成
reboot: System halted
附加信息：
Linux系統有7個運行級別(runlevel)
Linux系統有7個運行級別(runlevel)
運行級別0：系統停機狀態，系統默認運行級別不能設爲0，否則不能正常啓動
運行級別1：單用戶工作狀態，root權限，用於系統維護，禁止遠程登陸
運行級別2：多用戶狀態(沒有NFS)
運行級別3：完全的多用戶狀態(有NFS)，登陸後進入控制檯命令行模式
運行級別4：系統未使用，保留
運行級別5：X11控制檯，登陸後進入圖形GUI模式
運行級別6：系統正常關閉並重啓，默認運行級別不能設爲6，否則不能正常啓動
多數的桌面的linux系統缺省的runlevel是5，用戶登陸時是圖形界面，而多數的服務器版本的linux系統缺省的runlevel是3，用戶登陸時是字符界面，runlevel 1和2除了調試之外很少使用，runlevel s和S並不是直接給用戶使用，而是用來爲Single user mode作準備。
在基於Busybox的系統上執行busybox --list即可看到一個系統可用命令列表