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基于tiny4412的Linux内核移植（支持device tree）（三）

2016-03-22 17:03 603 查看

转自：http://www.cnblogs.com/pengdonglin137/p/5146791.html

阅读目录(Content)

作者信息
平台简介
注意

一、设备树反编译
二、在u-boot打印信息
三、打开Linux内核启动早期的log
四、在内核自解压时dump内存
五、CONFIG_ARM_APPENDED_DTB

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作者信息

作者:彭东林

邮箱：pengdonglin137@163.com

QQ：405728433

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平台简介

开发板：tiny4412ADK+S700+4GBFlash

要移植的内核版本：Linux-4.4.0（支持devicetree）

u-boot版本：友善之臂自带的U-Boot2010.12（为支持uImage启动，做了少许改动）

busybox版本：busybox1.25

交叉编译工具链：arm-none-linux-gnueabi-gcc

（gccversion4.8.320140320(prerelease)(SourceryCodeBenchLite2014.05-29)）

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注意

继续上文。

到目前为止，板子已经可以起来了，接下来就可以针对板子的情况移植驱动程序了。这个放在以后再做，下面是我折腾过程中得到的一些知识，分享一下。

一、设备树反编译

在内核目录下当我们执行makedtbs后，就会在arch/arm/boot/dts下生成一些.dtb文件，那这个文件里是什么东西呢？我们可以用dtc命令反编译这些dtb文件，下面以exynos4412-tiny4412.dtb为例：

命令：

dtc-Idtb-Odtb-otiny4412.dtsarch/arm/boot/dts/exynos4412-tiny4412.dtb

然后就会生成反编译后的文件tiny4412.dts，部分内容如下：

/dts-v1/;

/{
#address-cells=<;0x1>;
#size-cells=<;0x1>;
interrupt-parent=<;0x1>;
compatible="friendlyarm,tiny4412","samsung,exynos4412","samsung,exynos4";
model="FriendlyARMTINY4412boardbasedonExynos4412";

chosen{
stdout-path="/serial@13800000";
bootargs="root=/dev/ram0rwrootfstype=ext4console=ttySAC0,115200init=/linuxrcearlyprintk";
};

aliases{
spi0="/spi@13920000";
spi1="/spi@13930000";
spi2="/spi@13940000";
i2c0="/i2c@13860000";
i2c1="/i2c@13870000";
i2c2="/i2c@13880000";
i2c3="/i2c@13890000";
i2c4="/i2c@138A0000";
i2c5="/i2c@138B0000";
i2c6="/i2c@138C0000";
i2c7="/i2c@138D0000";
i2c8="/i2c@138E0000";
csis0="/camera/csis@11880000";
csis1="/camera/csis@11890000";
fimc0="/camera/fimc@11800000";
fimc1="/camera/fimc@11810000";
fimc2="/camera/fimc@11820000";
fimc3="/camera/fimc@11830000";
serial0="/serial@13800000";
serial1="/serial@13810000";
serial2="/serial@13820000";
serial3="/serial@13830000";
pinctrl0="/pinctrl@11400000";
pinctrl1="/pinctrl@11000000";
pinctrl2="/pinctrl@03860000";
pinctrl3="/pinctrl@106E0000";
fimc-lite0="/camera/fimc-lite@12390000";
fimc-lite1="/camera/fimc-lite@123A0000";
mshc0="/mmc@12550000";
};

memory{
device_type="memory";
reg=<0x400000000x40000000>;
};

clock-controller@03810000{
compatible="samsung,exynos4210-audss-clock";
reg=<0x38100000xc>;
#clock-cells=<;0x1>;
linux,phandle=<;0x2>;
phandle=<;0x2>;
};
i2s@03830000{

这个方法对于学习设备树很有帮助。

二、在u-boot打印信息

在u-boot中很多文件中是通过debug(……)来打印信息，默认情况下这些log是打印不出来的。这个函数的定义是在include/common.h中：

#ifdefDEBUG

#definedebug(fmt,args...)printf(fmt,##args)

#definedebugX(level,fmt,args...)if(DEBUG>=level)printf(fmt,##args);

#else

#definedebug(fmt,args...)

#definedebugX(level,fmt,args...)

#endif/*DEBUG*/

所以可以在调用debug函数的C文件的最上面添加#defineDEBUG即可。这个方法在Linux内核以及Android当中也很常用。

三、打开Linux内核启动早期的log

有时会遇到当在u-boot中执行完bootm后，打印出startkernel后串口就没有再输出任何信息了。此时就需要打开内核早期的log：

makemenuconfig

Kernelhacking--->

[*]Kernellow-leveldebuggingfunctions(readhelp!)

Kernellow-leveldebuggingport(UseSamsungS3CUART0forlow-leveldebug)

[*]Earlyprintk

对于earlyprintk，还需要在bootargs中添加参数earlyprintk才能生效，有了上面这几个配置，会有下面几个宏生效：

CONFIG_DEBUG_LL=y

CONFIG_DEBUG_S3C_UART0=y

CONFIG_DEBUG_LL_INCLUDE="debug/exynos.S"

CONFIG_DEBUG_UNCOMPRESS=y

CONFIG_UNCOMPRESS_INCLUDE="debug/uncompress.h"

CONFIG_EARLY_PRINTK=y

关于earlyprintk的解析在文件arch/arm/kernel/early_printk.c中：

1:externvoidprintch(int);

2:

3:staticvoidearly_write(constchar*s,unsignedn)

4:{

5:while(n-->;0){

6:if(*s=='\n')

7:printch('\r');

8:printch(*s);

9:s++;

10:}

11:}

12:

13:staticvoidearly_console_write(structconsole*con,constchar*s,unsignedn)

14:{

15:early_write(s,n);

16:}

17:

18:staticstructconsoleearly_console_dev={

19:.name="earlycon",

20:.write=early_console_write,

21:.flags=CON_PRINTBUFFER|CON_BOOT,

22:.index=-1,

23:};

24:

25:staticint__initsetup_early_printk(char*buf)

26:{

27:early_console=&;early_console_dev;

28:register_console(&;early_console_dev);

29:return0;

30:}

31:

32:early_param("earlyprintk",setup_early_printk);

其中printch都是通过汇编语言实现的。

在arch/arm/Kconfig.debug中可以看到：

configDEBUG_LL

bool"Kernellow-leveldebuggingfunctions(readhelp!)"

dependsonDEBUG_KERNEL

help

SayYheretoincludedefinitionsofprintascii,printch,printhex

inthekernel.Thisishelpfulifyouaredebuggingcodethat

executesbeforetheconsoleisinitialized.

configDEBUG_S3C_UART0

dependsonPLAT_SAMSUNG

selectDEBUG_EXYNOS_UARTifARCH_EXYNOS

selectDEBUG_S3C24XX_UARTifARCH_S3C24XX

selectDEBUG_S5PV210_UARTifARCH_S5PV210

bool"UseSamsungS3CUART0forlow-leveldebug"

help

SayYhereifyouwantthedebugprintroutinestodirect

theiroutputtoUART0.Theportmusthavebeeninitialised

bytheboot-loaderbeforeuse.

configDEBUG_LL_INCLUDE

string

……

default"debug/exynos.S"ifDEBUG_EXYNOS_UART

configEARLY_PRINTK

bool"Earlyprintk"

dependsonDEBUG_LL

help

SayYhereifyouwanttohaveanearlyconsoleusingthe

kernellow-leveldebuggingfunctions.Addearlyprintktoyour

kernelparameterstoenablethisconsole.

从上面的信息我们可以知道：

在串口终端尚未注册时，内核定义了printascii、printch以及printhex用于调试；
earlyconsole使用的也是上面定义的函数，需要在传递给内核的参数中添加earlyprintk参数
Linux内核早期的print函数的输出串口要跟u-boot下使用的一致，即内核不再负责初始化了，让u-boot来做，所以二者一定要一致，否则那些print函数以及earlyprintk都没法输出信息；
可以参考arch/arm/kernel/debug.S，printascii、printch以及printhex都是在这里定义的；
在kernel进入C函数（start_kernel）后可以调用early_print来打印信息，它是在arch/arm/kernel/setup.c中定义的：

1:void__initearly_print(constchar*str,...)

2:{

3:externvoidprintascii(constchar*);

4:charbuf[256];

5:va_listap;

6:

7:va_start(ap,str);

8:vsnprintf(buf,sizeof(buf),str,ap);

9:va_end(ap);

10:

11:#ifdefCONFIG_DEBUG_LL

12:printascii(buf);

13:#endif

14:printk("%s",buf);

15:}

可以看到，early_print也会调用printascii和printk，意思是用early_print打印的信息可能会重复出现在终端上（printk会缓冲一部分,当bootconsole注册后，会将printk缓冲区中的内容输出）。

上面所说的打印函数只能在内核自解压后的函数中才能使用，那么内核自解压过程中的信息是不是也可以打印呢？可以，内核自解压相关的文件在arch/arm/boot/compressed/下面，我们所熟知的：

UncompressingLinux...done,bootingthekernel.

就是这个目录下的代码打印出来的，具体代码如下：

arch/arm/boot/compressed/misc.c

1:void

2:decompress_kernel(unsignedlongoutput_start,unsignedlongfree_mem_ptr_p,

3:unsignedlongfree_mem_ptr_end_p,

4:intarch_id)

5:{

6:......

7:putstr("UncompressingLinux...");

8:ret=do_decompress(input_data,input_data_end-input_data,

9:output_data,error);

10:......

11:putstr("done,bootingthekernel.\n");

12:}

其中，putstr的定义如下:

1:staticvoidputstr(constchar*ptr)

2:{

3:charc;

4:

5:while((c=*ptr++)!='\0'){

6:if(c=='\n')

7:putc('\r');

8:putc(c);

9:}

10:

11:flush();

12:}

putc是汇编实现的，arch/arm/boot/compressed/debug.S：

1:#includeCONFIG_DEBUG_LL_INCLUDE

2:

3:ENTRY(putc)

4:addruartr1,r2,r3

5:waituartr3,r1

6:senduartr0,r1

7:busyuartr3,r1

8:movpc,lr

9:ENDPROC(putc)

10:

11:

其中addruart的实现因soc的不同而不同，对于exynos4412，它的实现是（arch/arm/include/debug/exynos.S）：

1:.macroaddruart,rp,rv,tmp

2:mrcp15,0,\tmp,c0,c0,0

3:and\tmp,\tmp,#0xf0

4:teq\tmp,#0xf0@@A15

5:ldreq\rp,=EXYNOS5_PA_UART

6:movne\rp,#EXYNOS4_PA_UART@@EXYNOS4

7:ldr\rv,=S3C_VA_UART

8:CONFIG_DEBUG_S3C_UART!=0

9:add\rp,\rp,#(0x10000*CONFIG_DEBUG_S3C_UART)

10:add\rv,\rv,#(0x10000*CONFIG_DEBUG_S3C_UART)

11:if

12:.endm

这个函数的目的就是获得控制调试uart的寄存器的物理基地址(rp)和虚拟基地址(rv),这里也没有初始化uart的代码，所以必须跟u-boot使用的串口一致。

四、在内核自解压时dump内存

这是在调试设备树在内存中的镜像被自解压后的内核覆盖时发现的。下面是使用方法：

首先需要按照上面的一节配置内核打开那几个宏
修改arch/arm/boot/compressed/head.S，如下：

1:diff--gita/arch/arm/boot/compressed/head.Sb/arch/arm/boot/compressed/head.S

2:index06e983f..7ecde2e100644

3:---a/arch/arm/boot/compressed/head.S

4:+++b/arch/arm/boot/compressed/head.S

5:@@-22,6+22,8@@

6:*100%relocatable.Anyattempttodosowillresultinacrash.

7:*Pleaseselectoneofthefollowingwhenturningondebugging.

8:*/

9:+#defineDEBUG

10:+

11:#ifdefDEBUG

12:

13:#ifdefined(CONFIG_DEBUG_ICEDCC)

14:@@-65,7+67,7@@

15:.endm

16:#else

17:.macroloadsp,rb,tmp

18:-addruart\rb,\tmp

19:+addruart\rb,\tmp,\tmp

20:.endm

21:#endif

22:#endif

23:@@-536,6+538,24@@not_relocated:movr0,#0

24:*r7=architectureID

25:*r8=atagspointer

26:*/

27:+stmfdsp!,{r0-r3,r10-r12,lr}

28:+kputc#'\n'

29:+kputc#'a'

30:+kputc#'t'

31:+kputc#'a'

32:+kputc#'g'

33:+kputc#'s'

34:+kputc#':'

35:+kputc#''

36:+kputc#'0'

37:+kputc#'x'

38:+kphexr8,8/*atagspointer*/

39:+kputc#'\n'

40:+movr0,r8

41:+blmemdump/*dump256bytesatstartofkernel*/

42:+kputc#'\n'

43:+ldmfdsp!,{r0-r3,r10-r12,lr}

44:+

45:movr0,r4

46:movr1,sp@mallocspaceabovestack

47:addr2,sp,#0x10000@64kmax

48:@@-546,6+566,26@@not_relocated:movr0,#0

49:movr1,r7@restorearchitecturenumber

50:movr2,r8@restoreatagspointer

51:

52:+stmfdsp!,{r0-r3,r10-r12,lr}

53:+kputc#'\n'

54:+kputc#'\n'

55:+kputc#'a'

56:+kputc#'t'

57:+kputc#'a'

58:+kputc#'g'

59:+kputc#'s'

60:+kputc#':'

61:+kputc#''

62:+kputc#'0'

63:+kputc#'x'

64:+kphexr8,8/*atagspointer*/

65:+kputc#'\n'

66:+movr0,r8

67:+blmemdump/*dump256bytesatstartofkernel*/

68:+kputc#'\n'

69:+ldmfdsp!,{r0-r3,r10-r12,lr}

70:+

71:+

72:#ifdefCONFIG_ARM_VIRT_EXT

73:mrsr0,spsr@GetsavedCPUbootmode

74:andr0,r0,#MODE_MASK

可以使用kputc打印出一个字符，kphex用于打印一个指定位宽的十六进制数，将需要dump的内粗地址存放入r0，然后调用memdump即可，memdump会dump出256B的内容。u-boot在跳转到内核的时候传递三个参数，分别给了r0、r1、r2，在没有设备树之前，传给r0,r1和r2的分别是0，machid以及u-boot传给Linux内核参数的地址（如0x40000100）,在有了设备树之后，传给r0的是0，传给r1的值无所谓，传给r2的是设备树镜像在内存中的地址。效果如下：

U-Boot2010.12-00000-gb391276-dirty(Jan172016-06:03:22)forTINY4412

CPU:S5PC220[SamsungSOConSMPPlatformBaseonARMCortexA9]

APLL=1400MHz,MPLL=800MHz

Board:TINY4412

DRAM:1023MiB

vdd_arm:1.2

vdd_int:1.0

vdd_mif:1.1

BL1version:N/A(TrustZoneEnabledBSP)

CheckingBootMode...SDMMC

REVISION:1.1

MMCDevice0:3803MB

MMCDevice1:3728MB

MMCDevice2:N/A

***Warning-usingdefaultenvironment

Net:Noethernetfound.

Hitanykeytostopautoboot:0

TINY4412#

TINY4412#dnw0x40000000

OTGcableConnected!

Now,WaitingforDNWtotransmitdata

DownloadDone!!DownloadAddress:0x40000000,DownloadFilesize:0x43bde8

Checksumisbeingcalculated.....

ChecksumO.K.

TINY4412#dnw0x41000000

OTGcableConnected!

Now,WaitingforDNWtotransmitdata

DownloadDone!!DownloadAddress:0x41000000,DownloadFilesize:0x27752e

Checksumisbeingcalculated...

ChecksumO.K.

TINY4412#dnw0x42000000

OTGcableConnected!

Now,WaitingforDNWtotransmitdata

DownloadDone!!DownloadAddress:0x42000000,DownloadFilesize:0xa53a

Checksumisbeingcalculated.

ChecksumO.K.

TINY4412#bootm0x400000000x410000000x42000000

##BootingkernelfromLegacyImageat40000000...

ImageName:Linux-4.4.0-gbd49c0f-dirty

ImageType:ARMLinuxKernelImage(uncompressed)

DataSize:4439464Bytes=4335KiB

LoadAddress:40008000

EntryPoint:40008000

VerifyingChecksum...OK

##LoadinginitRamdiskfromLegacyImageat41000000...

ImageName:ramdisk

ImageType:ARMLinuxRAMDiskImage(gzipcompressed)

DataSize:2585838Bytes=2525KiB

LoadAddress:00000000

EntryPoint:00000000

VerifyingChecksum...OK

##FlattenedDeviceTreeblobat42000000

Bootingusingthefdtblobat0x42000000

LoadingKernelImage...OK

OK

##LoadinginitRamdiskfromLegacyImageat41000000...

ImageName:ramdisk

ImageType:ARMLinuxRAMDiskImage(gzipcompressed)

DataSize:2585838Bytes=2525KiB

LoadAddress:00000000

EntryPoint:00000000

VerifyingChecksum...OK

LoadingRamdiskto43a84000,end43cfb4ee...OK

LoadingDeviceTreeto413f2000,end413ff539...OK

Startingkernel...

atags:0x413F2000

413F2000:EDFE0DD03AD5000048000000849E000028000000110000001000000000000000

413F2020:220700003C9E0000000000000040A84300000000EF7427000000000000000000

413F2040:0000000000000000010000000000000003000000040000000000000001000000

413F2060:03000000040000000F0000000100000003000000040000001B00000001000000

413F2080:03000000380000002C00000065697266796C646E2C6D7261796E697432313434

413F20A0:6D617300676E75737978652C34736F6E00323134736D61732C676E756E797865

413F20C0:0034736F030000002F0000003700000065697246796C646E204D5241594E4954

413F20E0:32313434616F62206220647264657361206E6F206E7978453434736F00003231

UncompressingLinux...done,bootingthekernel.

atags:0x413F2000

413F2000:EDFE0DD03AD5000048000000849E000028000000110000001000000000000000

413F2020:220700003C9E0000000000000040A84300000000EF7427000000000000000000

413F2040:0000000000000000010000000000000003000000040000000000000001000000

413F2060:03000000040000000F0000000100000003000000040000001B00000001000000

413F2080:03000000380000002C00000065697266796C646E2C6D7261796E697432313434

413F20A0:6D617300676E75737978652C34736F6E00323134736D61732C676E756E797865

413F20C0:0034736F030000002F0000003700000065697246796C646E204D5241594E4954

413F20E0:32313434616F62206220647264657361206E6F206E7978453434736F00003231

[0.000000]BootingLinuxonphysicalCPU0xa00

[0.000000]Linuxversion4.4.0-gbd49c0f-dirty(root@ubuntu)(gccversion4.8.320140320(prerelease)(SourceryCodeBenchLite2014.05-29))#25SMPPREEMPTTueJan1905:50:47PST2016

[0.000000]CPU:ARMv7Processor[413fc090]revision0(ARMv7),cr=10c5387d

[0.000000]CPU:PIPT/VIPTnonaliasingdatacache,VIPTaliasinginstructioncache

[0.000000]Machinemodel:FriendlyARMTINY4412boardbasedonExynos4412

[0.000000]bootconsole[earlycon0]enabled

[0.000000]cma:Reserved64MiBat0x7bc00000

[0.000000]Memorypolicy:Datacachewritealloc

[0.000000]SamsungCPUID:0xe4412011

[0.000000]PERCPU:Embedded12pages/cpu@ef79b000s18816r8192d22144u49152

[0.000000]Built1zonelistsinZoneorder,mobilitygroupingon.Totalpages:260352

[0.000000]Kernelcommandline:root=/dev/ram0rwrootfstype=ext4console=ttySAC0,115200init=/linuxrcearlyprintk

[0.000000]PIDhashtableentries:4096(order:2,16384bytes)

[0.000000]Dentrycachehashtableentries:131072(order:7,524288bytes)

[0.000000]Inode-cachehashtableentries:65536(order:6,262144bytes)

[0.000000]Memory:960824K/1047552Kavailable(5867Kkernelcode,293Krwdata,2288Krodata,440Kinit,315Kbss,21192Kreserved,65536Kcma-reserved,195584Khighmem)

[0.000000]Virtualkernelmemorylayout:

[0.000000]vector:0xffff0000-0xffff1000(4kB)

[0.000000]fixmap:0xffc00000-0xfff00000(3072kB)

[0.000000]vmalloc:0xf0800000-0xff800000(240MB)

[0.000000]lowmem:0xc0000000-0xf0000000(768MB)

[0.000000]pkmap:0xbfe00000-0xc0000000(2MB)

[0.000000]modules:0xbf000000-0xbfe00000(14MB)

[0.000000].text:0xc0008000-0xc07ff200(8157kB)

[0.000000].init:0xc0800000-0xc086e000(440kB)

[0.000000].data:0xc086e000-0xc08b7418(294kB)

[0.000000].bss:0xc08ba000-0xc0908d28(316kB)

可以看到UncompressingLinux...done,bootingthekernel.前后就是dump出的设备树的内容（大小端可能有些问题）.

五、CONFIG_ARM_APPENDED_DTB

这个宏是Linux内核中的，它的作用是支持zImage+dtb的启动方式。为什么要有种方式呢？因为很多厂家都有自己的bootloader，但是这些bootloader并不都一定支持设备树，为了实现支持设备树启动，就引入了这种启动方式，即将编译出的zImage和编译出的设备树镜像文件拼成一个新的镜像，在内核的自解压代码中会识别到，不会出现自解压时导致设备树被覆盖，具体实现如下（arch/arm/boot/compressed/head.S）

movr5,#0@initdtbsizeto0

#ifdefCONFIG_ARM_APPENDED_DTB

/*

*r0=delta

*r2=BSSstart

*r3=BSSend

*r4=finalkerneladdress(possiblywithLSBset)

*r5=appendeddtbsize(stillunknown)

*r6=_edata

*r7=architectureID

*r8=atags/devicetreepointer

*r9=sizeofdecompressedimage

*r10=endofthisimage,includingbss/stack/mallocspaceifnonXIP

*r11=GOTstart

*r12=GOTend

*sp=stackpointer

*iftherearedevicetrees(dtb)appendedtozImage,advancer10sothatthe

*dtbdatawillgetrelocatedalongwiththekernelifnecessary.

*/

ldrlr,[r6,#0]

#ifndef__ARMEB__

ldrr1,=0xedfe0dd0@sigis0xd00dfeedbigendian

#else

ldrr1,=0xd00dfeed

#endif

cmplr,r1

bnedtb_check_done@notfound

#ifdefCONFIG_ARM_ATAG_DTB_COMPAT

/*

*OK...Let'sdosomefunkybusinesshere.

*IfwedohaveaDTBappendedtozImage,andwedohave

*anATAGlistaround,wewantthelatertobetranslated

*andfoldedintotheformerhere.NoGOTfixuphasoccurred

*yet,butnoneofthecodewe'reabouttocallusesany

*globalvariable.

*/

/*GettheinitialDTBsize*/

ldrr5,[r6,#4]

#ifndef__ARMEB__

/*converttolittleendian*/

eorr1,r5,r5,ror#16

bicr1,r1,#0x00ff0000

movr5,r5,ror#8

eorr5,r5,r1,lsr#8

#endif

/*50%DTBgrowthshouldbegoodenough*/

addr5,r5,r5,lsr#1

/*preserve64-bitalignment*/

addr5,r5,#7

bicr5,r5,#7

/*clampto32KBminand1MBmax*/

cmpr5,#(1<;<15)

movlor5,#(1<;<15)

cmpr5,#(1<;<20)

movhir5,#(1<;<20)

/*temporarilyrelocatethestackpasttheDTBworkspace*/

addsp,sp,r5

stmfdsp!,{r0-r3,ip,lr}

movr0,r8

movr1,r6

movr2,r5

blatags_to_fdt

/*

*Ifreturnedvalueis1,thereisnoATAGatthelocation

*pointedbyr8.Trythetypical0x100offsetfromstart

*ofRAMandhopeforthebest.

*/

cmpr0,#1

subr0,r4,#TEXT_OFFSET

bicr0,r0,#1

addr0,r0,#0x100

movr1,r6

movr2,r5

bleqatags_to_fdt

ldmfdsp!,{r0-r3,ip,lr}

subsp,sp,r5

#endif

movr8,r6@usetheappendeddevicetree

/*

*MakesurethattheDTBdoesn'tendupinthefinal

*kernel's.bssarea.Todoso,weadjustthedecompressed

*kernelsizetocompensateifthat.bsssizeislarger

*thantherelocatedcode.

*/

ldrr5,=_kernel_bss_size

adrr1,wont_overwrite

subr1,r6,r1

subsr1,r5,r1

addhir9,r9,r1

/*GetthecurrentDTBsize*/

ldrr5,[r6,#4]

#ifndef__ARMEB__

/*convertr5(dtbsize)tolittleendian*/

eorr1,r5,r5,ror#16

bicr1,r1,#0x00ff0000

movr5,r5,ror#8

eorr5,r5,r1,lsr#8

#endif

/*preserve64-bitalignment*/

addr5,r5,#7

bicr5,r5,#7

/*relocatesomepointerspasttheappendeddtb*/

addr6,r6,r5

addr10,r10,r5

addsp,sp,r5

dtb_check_done:

#endif

拼接方法：

catzImagedts/exynos4412-tiny4412.dtb>dtbImage

也可以修改内核编译系统，在编译完成后自动实现拼接，可以参考下面的博文实现：

/article/5055154.html

下面是使用dtbImage启动的方法：

1、修改设备树arch/arm/boot/dts/exynos4412-tiny4412.dts

diff--gita/arch/arm/boot/dts/exynos4412-tiny4412.dtsb/arch/arm/boot/dts/exynos4412-tiny4412.dts

index4840bbd..1e33ede100644

---a/arch/arm/boot/dts/exynos4412-tiny4412.dts

+++b/arch/arm/boot/dts/exynos4412-tiny4412.dts

@@-21,6+21,7@@

chosen{

stdout-path=&;serial_0;

+bootargs="root=/dev/ram0rwrootfstype=ext4ramdisk=8192initrd=0x41000000,8Mconsole=ttySAC0,115200init=/linuxrcmem=1024M"

};

memory{

@@-78,7+79,7@@

bus-width=<;4>;

pinctrl-0=<;&sd2_clk&sd2_cmd&sd2_cd&sd2_bus4>;

pinctrl-names="default";

-status="okay";

+status="disabled";

};

&;serial_0{

2、编译设备树makedtbs，将生成的.dtb跟zImag拼接起来生成dtbImage

3、使用ramdisk启动，目前不能使用ramdisk.img，还不知道为什么。

4、启动开发板，进入u-boot命令行模式，执行如下命令：

在u-boot里执行下载dtbImage的命令：dnw0x40008000

在开发机上执行：dnwdtbImage

在u-boot里执行下载ramdisk的命令：dnw0x41000000

在开发机上执行：dnwramdisk

启动内核：bootm0x40008000(u-boot不识别未压缩的ramdisk，ramdisk的地址在bootargs中指定为0x41000000，而且上面我们已经把ramdisk下载到0x41000000了)

下面是完整的log：

U-Boot2010.12-00000-gb391276-dirty(Jan172016-06:03:22)forTINY4412

CPU:S5PC220[SamsungSOConSMPPlatformBaseonARMCortexA9]

APLL=1400MHz,MPLL=800MHz

Board:TINY4412

DRAM:1023MiB

vdd_arm:1.2

vdd_int:1.0

vdd_mif:1.1

BL1version:N/A(TrustZoneEnabledBSP)

CheckingBootMode...SDMMC

REVISION:1.1

MMCDevice0:3803MB

MMCDevice1:3728MB

MMCDevice2:N/A

***Warning-usingdefaultenvironment

Net:Noethernetfound.

Hitanykeytostopautoboot:0

TINY4412#dnw0x40008000

OTGcableConnected!

Now,WaitingforDNWtotransmitdata

DownloadDone!!DownloadAddress:0x40008000,DownloadFilesize:0x446302

Checksumisbeingcalculated.....

ChecksumO.K.

TINY4412#dnw0x41000000

OTGcableConnected!

Now,WaitingforDNWtotransmitdata

DownloadDone!!DownloadAddress:0x41000000,DownloadFilesize:0x800000

Checksumisbeingcalculated.........

ChecksumO.K.

TINY4412#bootm0x40008000

BootwithzImage

Startingkernel...

atags:0x40CF68E8

40CF68E8:EDFE0DD072A5000038000000749E000028000000110000001000000000000000

40CF6908:FE0600003C9E0000000000000000000000000000000000000100000000000000

40CF6928:0300000004000000000000000100000003000000040000000F00000001000000

40CF6948:03000000040000001B0000000100000003000000380000002C00000065697266

40CF6968:796C646E2C6D7261796E6974323134346D617300676E75737978652C34736F6E

40CF6988:00323134736D61732C676E756E7978650034736F030000002F00000037000000

40CF69A8:65697246796C646E204D5241594E495432313434616F62206220647264657361

40CF69C8:206E6F206E7978453434736F0000323101000000736F686300006E6503000000

UncompressingLinux...done,bootingthekernel.

atags:0x40CF68E8

40CF68E8:EDFE0DD072A5000038000000749E000028000000110000001000000000000000

40CF6908:FE0600003C9E0000000000000000000000000000000000000100000000000000

40CF6928:0300000004000000000000000100000003000000040000000F00000001000000

40CF6948:03000000040000001B0000000100000003000000380000002C00000065697266

40CF6968:796C646E2C6D7261796E6974323134346D617300676E75737978652C34736F6E

40CF6988:00323134736D61732C676E756E7978650034736F030000002F00000037000000

40CF69A8:65697246796C646E204D5241594E495432313434616F62206220647264657361

40CF69C8:206E6F206E7978453434736F0000323101000000736F686300006E6503000000

[0.000000]BootingLinuxonphysicalCPU0xa00

[0.000000]Linuxversion4.4.0-gbd49c0f-dirty(root@ubuntu)(gccversion4.8.320140320(prerelease)(SourceryCodeBenchLite2014.05-29))#25SMPPREEMPTTueJan1905:50:47PST2016

[0.000000]CPU:ARMv7Processor[413fc090]revision0(ARMv7),cr=10c5387d

[0.000000]CPU:PIPT/VIPTnonaliasingdatacache,VIPTaliasinginstructioncache

[0.000000]Machinemodel:FriendlyARMTINY4412boardbasedonExynos4412

[0.000000]cma:Reserved64MiBat0x7c000000

[0.000000]Memorypolicy:Datacachewritealloc

[0.000000]SamsungCPUID:0xe4412011

[0.000000]PERCPU:Embedded12pages/cpu@ef79b000s18816r8192d22144u49152

[0.000000]Built1zonelistsinZoneorder,mobilitygroupingon.Totalpages:260608

[0.000000]Kernelcommandline:root=/dev/ram0rwrootfstype=ext4ramdisk=8192initrd=0x41000000,8Mconsole=ttySAC0,115200init=/linuxrcmem=1024M

[0.000000]PIDhashtableentries:4096(order:2,16384bytes)

[0.000000]Dentrycachehashtableentries:131072(order:7,524288bytes)

[0.000000]Inode-cachehashtableentries:65536(order:6,262144bytes)

[0.000000]Memory:956196K/1048576Kavailable(5867Kkernelcode,293Krwdata,2288Krodata,440Kinit,315Kbss,26844Kreserved,65536Kcma-reserved,196608Khighmem)

[0.000000]Virtualkernelmemorylayout:

[0.000000]vector:0xffff0000-0xffff1000(4kB)

[0.000000]fixmap:0xffc00000-0xfff00000(3072kB)

[0.000000]vmalloc:0xf0800000-0xff800000(240MB)

[0.000000]lowmem:0xc0000000-0xf0000000(768MB)

[0.000000]pkmap:0xbfe00000-0xc0000000(2MB)

[0.000000]modules:0xbf000000-0xbfe00000(14MB)

[0.000000].text:0xc0008000-0xc07ff200(8157kB)

[0.000000].init:0xc0800000-0xc086e000(440kB)

[0.000000].data:0xc086e000-0xc08b7418(294kB)

[0.000000].bss:0xc08ba000-0xc0908d28(316kB)

[0.000000]SLUB:HWalign=64,Order=0-3,MinObjects=0,CPUs=4,Nodes=1

[0.000000]PreemptiblehierarchicalRCUimplementation.

[0.000000]Build-timeadjustmentofleaffanoutto32.

[0.000000]RCUrestrictingCPUsfromNR_CPUS=8tonr_cpu_ids=4.

[0.000000]RCU:Adjustinggeometryforrcu_fanout_leaf=32,nr_cpu_ids=4

[0.000000]NR_IRQS:16nr_irqs:1616

[0.000000]GICphysicallocationis0x10490000

[0.000000]L2C:platformmodifiesauxcontrolregister:0x02070000->;0x3e470001

[0.000000]L2C:platformprovidedauxvaluespermitregistercorruption.

[0.000000]L2C:DT/platformmodifiesauxcontrolregister:0x02070000->;0x3e470001

[0.000000]L2C-310enablingearlyBRESPforCortex-A9

[0.000000]L2C-310:enablingfulllineofzerosbutnotenabledinCortex-A9

[0.000000]L2C-310dynamicclockgatingenabled,standbymodeenabled

[0.000000]L2C-310cachecontrollerenabled,16ways,1024kB

[0.000000]L2C-310:CACHE_ID0x4100c4c8,AUX_CTRL0x4e470001

[0.000000]Exynos4x12clocks:sclk_apll=466666667,sclk_mpll=800000000

[0.000000]sclk_epll=96000000,sclk_vpll=108000000,arm_clk=1400000000

[0.000000]Switchingtotimer-baseddelayloop,resolution41ns

[0.000000]clocksource:mct-frc:mask:0xffffffffmax_cycles:0xffffffff,max_idle_ns:79635851949ns

[0.000003]sched_clock:32bitsat24MHz,resolution41ns,wrapsevery89478484971ns

[0.000122]Console:colourdummydevice80x30

[0.000135]Calibratingdelayloop(skipped),valuecalculatedusingtimerfrequency..48.00BogoMIPS(lpj=120000)

[0.000144]pid_max:default:32768minimum:301

[0.000209]Mount-cachehashtableentries:2048(order:1,8192bytes)

[0.000217]Mountpoint-cachehashtableentries:2048(order:1,8192bytes)

[0.000586]CPU:Testingwritebuffercoherency:ok

[0.000772]CPU0:thread-1,cpu0,socket10,mpidr80000a00

[0.000999]Settingupstaticidentitymapfor0x400082c0-0x40008318

[0.045048]CPU1:thread-1,cpu1,socket10,mpidr80000a01

[0.060041]CPU2:thread-1,cpu2,socket10,mpidr80000a02

[0.075042]CPU3:thread-1,cpu3,socket10,mpidr80000a03

[0.075082]Broughtup4CPUs

[0.075096]SMP:Totalof4processorsactivated(192.00BogoMIPS).

[0.075101]CPU:AllCPU(s)startedinSVCmode.

[0.075611]devtmpfs:initialized

[0.084566]VFPsupportv0.3:implementor41architecture3part30variant9rev4

[0.084839]lcd0-power-domain@10023C80hasaschildsubdomain:tv-power-domain@10023C20.

[0.085225]clocksource:jiffies:mask:0xffffffffmax_cycles:0xffffffff,max_idle_ns:9556302231375000ns

[0.087164]pinctrlcore:initializedpinctrlsubsystem

[0.087929]NET:Registeredprotocolfamily16

[0.089226]DMA:preallocated256KiBpoolforatomiccoherentallocations

[0.105005]cpuidle:usinggovernorladder

[0.120000]cpuidle:usinggovernormenu

[0.120747]exynos-audss-clk3810000.clock-controller:setupcompleted

[0.157138]SCSIsubsysteminitialized

[0.157506]usbcore:registerednewinterfacedriverusbfs

[0.157580]usbcore:registerednewinterfacedriverhub

[0.157660]usbcore:registerednewdevicedriverusb

[0.158780]AdvancedLinuxSoundArchitectureDriverInitialized.

[0.159857]clocksource:Switchedtoclocksourcemct-frc

[0.169153]missingcooling_deviceproperty

[0.169163]failedtobuildthermalzonecpu-thermal:-2

[0.169260]NET:Registeredprotocolfamily2

[0.169627]TCPestablishedhashtableentries:8192(order:3,32768bytes)

[0.169686]TCPbindhashtableentries:8192(order:5,163840bytes)

[0.169803]TCP:Hashtablesconfigured(established8192bind8192)

[0.169921]UDPhashtableentries:512(order:2,24576bytes)

[0.169950]UDP-Litehashtableentries:512(order:2,24576bytes)

[0.170092]NET:Registeredprotocolfamily1

[0.170297]RPC:RegisterednamedUNIXsockettransportmodule.

[0.170305]RPC:Registeredudptransportmodule.

[0.170310]RPC:Registeredtcptransportmodule.

[0.170315]RPC:RegisteredtcpNFSv4.1backchanneltransportmodule.

[0.170461]Tryingtounpackrootfsimageasinitramfs...

[0.170628]rootfsimageisnotinitramfs(junkincompressedarchive);lookslikeaninitrd

[0.193515]Freeinginitrdmemory:8192K(c1000000-c1800000)

[0.194996]futexhashtableentries:1024(order:4,65536bytes)

[0.204233]romfs:ROMFSMTD(C)2007RedHat,Inc.

[0.204924]bounce:poolsize:64pages

[0.204936]ioschedulernoopregistered

[0.204945]ioschedulerdeadlineregistered

[0.205116]ioschedulercfqregistered(default)

[0.209955]dma-pl33012680000.pdma:LoadeddriverforPL330DMAC-141330

[0.209967]dma-pl33012680000.pdma:DBUFF-32x4bytesNum_Chans-8Num_Peri-32Num_Events-32

[0.213022]dma-pl33012690000.pdma:LoadeddriverforPL330DMAC-141330

[0.213032]dma-pl33012690000.pdma:DBUFF-32x4bytesNum_Chans-8Num_Peri-32Num_Events-32

[0.213909]dma-pl33012850000.mdma:LoadeddriverforPL330DMAC-141330

[0.213919]dma-pl33012850000.mdma:DBUFF-64x8bytesNum_Chans-8Num_Peri-1Num_Events-32

[0.271176]Serial:8250/16550driver,4ports,IRQsharingdisabled

[0.272413]13800000.serial:ttySAC0atMMIO0x13800000(irq=44,base_baud=0)isaS3C6400/10

[0.908554]console[ttySAC0]enabled

[0.912530]13810000.serial:ttySAC1atMMIO0x13810000(irq=45,base_baud=0)isaS3C6400/10

[0.921327]13820000.serial:ttySAC2atMMIO0x13820000(irq=46,base_baud=0)isaS3C6400/10

[0.930171]13830000.serial:ttySAC3atMMIO0x13830000(irq=47,base_baud=0)isaS3C6400/10

[0.939720][drm]Initializeddrm1.1.020060810

[0.953371]brd:moduleloaded

[0.958359]loop:moduleloaded

[0.959171]usbcore:registerednewinterfacedriverr8152

[0.959302]usbcore:registerednewinterfacedriverasix

[0.960434]usbcore:registerednewinterfacedriverax88179_178a

[0.966498]usbcore:registerednewinterfacedrivercdc_ether

[0.972325]usbcore:registerednewinterfacedriverdm9601

[0.977884]usbcore:registerednewinterfacedriversmsc75xx

[0.983611]usbcore:registerednewinterfacedriversmsc95xx

[0.989325]usbcore:registerednewinterfacedrivernet1080

[0.994965]usbcore:registerednewinterfacedrivercdc_subset

[1.000873]usbcore:registerednewinterfacedriverzaurus

[1.006454]usbcore:registerednewinterfacedrivercdc_ncm

[1.012397]ehci_hcd:USB2.0'Enhanced'HostController(EHCI)Driver

[1.018528]ehci-exynos:EHCIEXYNOSdriver

[1.022808]ohci_hcd:USB1.1'Open'HostController(OHCI)Driver

[1.028850]ohci-exynos:OHCIEXYNOSdriver

[1.033363]usbcore:registerednewinterfacedriverusb-storage

[1.039544]mousedev:PS/2mousedevicecommonforallmice

[1.045326]s3c-rtc10070000.rtc:failedtofindrtcsourceclock

[1.050645]s3c-rtc:probeof10070000.rtcfailedwitherror-2

[1.056739]i2c/deventriesdriver

[1.062046]device-mapper:ioctl:4.34.0-ioctl(2015-10-28)initialised:dm-devel@redhat.com

[1.069226]sdhci:SecureDigitalHostControllerInterfacedriver

[1.074585]sdhci:Copyright(c)PierreOssman

[1.079056]SynopsysDesignwareMultimediaCardInterfaceDriver

[1.086865]usbcore:registerednewinterfacedriverusbhid

[1.090471]usbhid:USBHIDcoredriver

[1.097222]NET:Registeredprotocolfamily10

[1.099233]sit:IPv6overIPv4tunnelingdriver

[1.103848]NET:Registeredprotocolfamily17

[1.107765]NET:Registeredprotocolfamily15

[1.112340]RegisteringSWP/SWPBemulationhandler

[1.118177]hctosys:unabletoopenrtcdevice(rtc0)

[1.134172]ALSAdevicelist:

[1.134208]Nosoundcardsfound.

[1.134917]RAMDISK:ext2filesystemfoundatblock0

[1.134972]RAMDISK:Loading8192KiB[1disk]intoramdisk...done.

[1.262918]EXT4-fs(ram0):mountedfilesystemwithreddatamode.Opts:(null)

[1.263014]VFS:Mountedroot(ext4filesystem)ondevice1:0.

[1.263132]devtmpfs:mounted

[1.263411]Freeingunusedkernelmemory:440K(c0800000-c086e000)

PleasepressEntertoactivatethisconsole.

[root@tiny4412]#

[root@tiny4412]#

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