Eboot（Uboot）相关函数
Eboot开始一段是用汇编写的，暂不考虑，跳到C函数后：
1
void
main(
void
)
2
{
3
BootloaderMain();
//Eboot的框架函数，在BLCOMMON模块中
4
SpinForever();
5
}
BLCOMMON路径 ：%_WINCEROOT%\Public\Common\Oak\Drivers\Ethdbg\Blcommon
框架函数BootloaderMain：
1
void
BootloaderMain (
void
)
2
{
3
DWORD dwAction;
4
DWORD dwpToc
=
0
;
5
DWORD dwImageStart
=
0
, dwImageLength
=
0
, dwLaunchAddr
=
0
;
6
BOOL bDownloaded
=
FALSE;
7
8
//
relocate globals to RAM
9
if
(
!
KernelRelocate (pTOC))
10
{
11
//
spin forever
12
HALT (BLERR_KERNELRELOCATE);
13
}
14
15
//
(1) Init debug support. We can use OEMWriteDebugString afterward.
16
if
(
!
OEMDebugInit ())
17
{
18
//
spin forever
19
HALT (BLERR_DBGINIT);
20
}
21
22
//
(2) initialize platform (clock, drivers, transports, etc)
23
if
(
!
OEMPlatformInit ())
24
{
25
//
spin forever
26
HALT (BLERR_PLATINIT);
27
}
28
29
//
(3) call OEM specific pre-download function
30
switch
(dwAction
=
OEMPreDownload ())
31
{
32
case
BL_DOWNLOAD:
//
在OEMLaunch中下载nk
33
//
(4) download image
34
if
(
!
DownloadImage (
&
dwImageStart,
&
dwImageLength,
&
dwLaunchAddr))//此处就是NK信息的获取函数，通过解析镜像文件获取
35
{
36
//
error already reported in DownloadImage
37
SPIN_FOREVER;
38
}
39
bDownloaded
=
TRUE;
40
41
//
Check for pTOC signature ("CECE") here, after image in place
42
if
(
*
(LPDWORD) OEMMapMemAddr (dwImageStart, dwImageStart
+
ROM_SIGNATURE_OFFSET)
==
ROM_SIGNATURE)
43
{
44
dwpToc
=
*
(LPDWORD) OEMMapMemAddr (dwImageStart, dwImageStart
+
ROM_SIGNATURE_OFFSET
+
sizeof
(ULONG));
45
//
need to map the content again since the pointer is going to be in a fixup address
46
dwpToc
=
(DWORD) OEMMapMemAddr (dwImageStart, dwpToc
+
g_dwROMOffset);
47
48
EdbgOutputDebugString (
"
ROMHDR at Address %Xh\r\n
"
, dwImageStart
+
ROM_SIGNATURE_OFFSET
+
sizeof
(DWORD));
//
right after signature
49
}
50
//
fall through
51
53
case
BL_JUMP:
54
55
if
(g_bBINDownload
&&
g_pOEMCheckSignature)
56
{
57
if
(
!
g_pOEMCheckSignature(dwImageStart, g_dwROMOffset, dwLaunchAddr, bDownloaded))
58
HALT(BLERR_CAT_SIGNATURE);
59
}
60
//
(4) final call to launch the image. never returned
61
OEMLaunch (dwImageStart, dwImageLength, dwLaunchAddr, (
const
ROMHDR
*
)dwpToc);
62
//
should never return
63
//
fall through
64
default
:
65
//
ERROR! spin forever
66
HALT (BLERR_INVALIDCMD);
67
}
68
}
69
启动函数OEMLaunch：
1
void
OEMLaunch( DWORD dwImageStart, DWORD dwImageLength, DWORD dwLaunchAddr,
const
ROMHDR
*
pRomHdr )
2
{
3
DWORD dwPhysLaunchAddr;
4
5
OALMSG(OAL_FUNC, (TEXT(
"
+OEMLaunch. dwImageStart =0x%x,dwImageLength=0x%x,dwLaunchAddr=0x%x\r\n
"
),dwImageStart,dwImageLength,dwLaunchAddr));
6
7
if
( g_bUSBDownload)
8
{
9
g_pTOC
->
id[g_dwTocEntry].dwLoadAddress
=
dwImageStart;
10
g_pTOC
->
id[g_dwTocEntry].dwTtlSectors
=
FILE_TO_SECTOR_SIZE(dwImageLength);
11
g_pTOC
->
id[g_dwTocEntry].dwJumpAddress
=
dwLaunchAddr;
12
if
(
!
WriteOSImageToBootMedia(dwImageStart, dwImageLength, dwLaunchAddr))//将OSImage写入Flash中
13
{
14
OALMSG(OAL_ERROR, (TEXT(
"
ERROR: OEMLaunch: Failed to store image to Smart Media.\r\n
"
)));
15
goto
CleanUp;
16
}
17
18
19
if
(
!
TOC_Write() ) //将TOC保存到Flash中
20
{
21
EdbgOutputDebugString(
"
*** OEMLaunch ERROR: TOC_Write failed! Next boot may not load from disk *** \r\n
"
);
22
}
23
TOC_Print();
24
}
25
else
26
{
27
EdbgOutputDebugString(
"
To start Launch OS! List TOC table :\r\n
"
);
28
TOC_Print();
29
dwLaunchAddr
=
g_pTOC
->
id[g_dwTocEntry].dwJumpAddress;
30
}
31
dwPhysLaunchAddr
=
(DWORD)OALVAtoPA((
void
*
)dwLaunchAddr);
32
OALMSG(TRUE, (TEXT(
"
INFO: OEMLaunch: Jumping to Physical Address 0x%Xh (Virtual Address 0x%Xh)...\r\n\r\n\r\n
"
), dwPhysLaunchAddr, dwLaunchAddr));
33
34
Launch(dwPhysLaunchAddr); //跳到OS起始地址
35
CleanUp:
36
37
OALMSG(TRUE, (TEXT(
"
ERROR: OEMLaunch: Halting...\r\n
"
)));
38
SpinForever();
39
}
OEMLaunch传入了内核镜像的起始地址dwImageStart、大小dwImageLength（用来将NK写入Flash中）和启动地址dwLaunchAddr（最终启动内核）。
通过USB下载NK时，则将其保存到Flash的TOC块中（TOC_Write（）），下次启动时就可以找到并加载NK了。
现只是大体理一下，还有好多细节问题需要整理。
参考：http://blog.csdn.net/nanjianhui/archive/2008/10/21/3111422.aspx