True FFS内核编程(简单笔记)

2006-08-22 19:22

True FFS内核编程

1 格式化FLASH

即使FLASH没有和块设备驱动绑定，也可对其进行格式化。

tffsDevFormat (int tffsDriveNo, int formatArg);

typedef struct

{

tffsFormatParams formatParams;

unsigned formatFlags;

} tffsDevFormatParams;

2 创建Boot Image区域

2.1 创建Boot Image区域

创建Boot Image区域，通过在格式化flash，使TFFS段从某个偏移的位置开始。

tffsFormatParams

typedef struct {

long int bootImageLen; //保留给Boot Image空间大小

unsigned percentUse;

unsigned noOfSpareUnits;

unsigned long vmAddressingLimit;

int (*progressCallback)(int totalUnitsToFormat, int totalUnitsFormattedSoFar);

char * volumeLabel;

unsigned noOfFATcopies;

unsigned embeddedCISlength;

char * embeddedCIS;

} tffsFormatParams;

STATUS sysTffsFormat (void)

{

STATUS status;

tffsDevFormatParams params =

{

#define HALF_FORMAT /* lower 0.5MB for bootimage, upper 1.5MB for TFFS */

#ifdef HALF_FORMAT

{0x80000l, 99, 1, 0x10000l, NULL, {0,0,0,0}, NULL, 2, 0, NULL},

#else

{0x000000l, 99, 1, 0x10000l, NULL, {0,0,0,0}, NULL, 2, 0, NULL},

#endif /* HALF_FORMAT */

FTL_FORMAT_IF_NEEDED

};

/* we assume that the drive number 0 is RFA */

status = tffsDevFormat (0, (int)&params);

return (status);

}

问题：这里保留的长度为0x80000l，为什么说是0.5M，不止啊？

2.2 写Boot Image到FLASH

采用函数tffsBootImagePut()实现，该函数依赖tffsRawio()，所以不能在TFFS卷装载以后使用。

TffsBootImagePut()能直接操作FLASH的任何区域。

函数定义：

STATUS tffsBootImagePut

(

int driveNo, /* TFFS drive number */

int offset, /* offset in the flash chip/card */

char * filename /* binary format of the bootimage */

)

3 mounting the driver

函数usrTffsConfig()把dosFile文件系统加载到TFFS Flash驱动上。

STATUS usrTffsConfig

(

int drive, /* drive number of TFFS */

int removable, /* 0 for nonremovable flash media */

char * fileName /* mount point */

)

STATUS usrTffsConfig ( int drive, int removable, char * fileName )

{

int dosFsCacheSizeDefault = 128 * 1024 ;

CBIO_DEV_ID pCbio;

BLK_DEV * pBlkDev;

char devName [BOOT_FILE_LEN];

if ((UINT)drive >= noOfDrives) {

printErr ("drive is out of range (0-%d)./n", noOfDrives - 1);

return (ERROR);

}

/* create a block device spanning entire disk (non-distructive!) */

if ((pBlkDev = tffsDevCreate (drive, removable)) == NULL) {

printErr ("tffsDevCreate failed./n");

return (ERROR);

}

/* split off boot device from boot file */

devSplit (fileName, devName);

/* initialize the block device as a dosFs device named */

/* Create e.g. 128 Kbytes disk cache */

if ( (pCbio = dcacheDevCreate( (CBIO_DEV_ID) pBlkDev, NULL,

dosFsCacheSizeDefault, devName)) == NULL )

return (ERROR);

if (dosFsDevCreate (devName, pCbio, 0, NONE) != OK)

return (ERROR);

return (OK);

}

4 TFFS SHELL命令

格式化flash，但保留Boot Image区域。

-> sysTffsFormat

加载RFA medium做为驱动0

-> usrTffsConfig 0,0,"/RFA/"