mkyaffs2image工具解析

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mkyaffs2image工具解析

来自：http://blogold.chinaunix.net/u3/104683/showart_2504330.html

mkyaffs2image工具解析

文件:mkyaffs2image.tar.gz大小:147KB下载:下载终于可以成功制作页大小为2K + 64 Bytes 的nand flash的image 文件了。令人兴奋啊：)

这两天一直苦于自己制作的yaffs2 image文件系统无法被linux-2.6.29.1内核识别，而使用FriendlyARM的mkyaffs2imag-128M工具就没有这个问题。一开始便判断是mkyaffs2image工具有问题，没有生成正确格式的yaffs2 image文件，从而导致内核无法识别，并抛出以下错误信息：

----------------------------------------------------------------------------------------------------------------

……

block 155 is bad
yaffs_read_super: isCheckpointed 0
VFS: Mounted root (yaffs filesystem) readonly on device 31:2.
Freeing init memory: 164K
Warning: unable to open an initial console.
Failed to execute /linuxrc. Attempting defaults...
Kernel panic - not syncing: No init found. Try passing init= option to kernel.

----------------------------------------------------------------------------------------------------------------

网上查了很多相关的资料，对2K data + 64bytes spare 的nand flash上yaffs2文件的存储格式并没有较为清晰的说明。不知道数据的存储模式，就无法正确生成image文件。苦恼了好几天，甚至有些想放弃了。。。

然而今天得到了一个意外的收获，http://www.bluewatersys.com/quickstart/9260sambootassistant.php上大概阐述了2K yaffs2 nand flash中数据的组织形式(虽然后来发现该文章中关于结构yaffs2_PackedTags的大小表述有错，应该是28字节，而非25字节)，经过修改后，并且纠正相关bug，成功生成正确的yaffs2 image 文件，download进s3c2440开发板后，顺利启动系统。

有一点很重要，就是mkyaffs2image生成的image 文件的OOB区数据格式要与linux kernel对nand flash进行读取时的数据格式保持一致，所以mkyaffs2image.c中来自linux kernel的数据结构，即包含了mtd-abi.h头文件。

PS：下面本人会附上mkyaffs2image.c的全部内容，供朋友们参考，希望给meet with同样error的兄弟们一些帮助：)

PART2 About 64bytes OOB

下图为64bytes OOB区中的数据组织结构：

图1 64bytes OOB area

PS：

1) OOB最前端的2bytes为0xFF 0xFF，用于标识为非坏块。

2) 每256bytes的数据需要3bytes有ECC校验，因此2K的数据需要24bytes的ECC。

以下为经过修改过后的mkyaffs2image.c的源码：

/*
* YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
*
* Copyright (C) 2002-2007 Aleph One Ltd.
* for Toby Churchill Ltd and Brightstar Engineering
*
* Created by Charles Manning <charles@aleph1.co.uk>
* Nick Bane modifications flagged NCB
* Endian handling patches by James Ng.
* mkyaffs2image hacks by NCB
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/

/*
* makeyaffs2image.c
*
* Makes a YAFFS2 file system image that can be used to load up a file system.
* Uses default Linux MTD layout - change if you need something different.
*/

#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <string.h>
#include <unistd.h>
#define __user
#include <mtd/mtd-user.h>
#include "yaffs_ecc.h"
#include "yaffs_guts.h"

#include "yaffs_packedtags2.h"

#include "mtd-abi.h" //ADDED BY LIUHAO 2009-11-11

unsigned yaffs_traceMask=0;

#define MAX_OBJECTS 10000

#define chunkSize 2048
#define spareSize 64

//MODIFIED BY LIUHAO 2009-11-11 START
//#define PT2_BYTES 25 //Original
#define PT2_BYTES 28
//MODIFIED BY LIUHAO 2009-11-11 END

const char * mkyaffsimage_c_version = "$Id: mkyaffs2image.c,v 1.4 2007-02-14 01:09:06 wookey Exp $";

static int layout_no;

static struct nand_oobinfo oob_layout[] = {
    /* KSI:
     * Dummy "raw" layout - no ECC, all the bytes are free. Does NOT
     * really work, only used for compatibility with CVS YAFFS2 that
     * never ever worked with any stock MTD.
     */
    {
        .useecc = MTD_NANDECC_AUTOPLACE,
        .eccbytes = 0,
        .eccpos = {},
        .oobfree = { {0, 64} }
    },
    /* KSI:
     * Regular MTD AUTOPLACED ECC for large page NAND devices, the
     * only one existing in stock MTD so far. It corresponds to layout# 1
     * in command line arguments. Any other layouts could be added to
     * the list when they made their way in kernel's MTD. The structure
     * is simply copied from kernel's drivers/mtd/nand/nand_base.c as-is.
     */
    {
        .useecc = MTD_NANDECC_AUTOPLACE,
        .eccbytes = 24,
        .eccpos = {
            40, 41, 42, 43, 44, 45, 46, 47,
            48, 49, 50, 51, 52, 53, 54, 55,
            56, 57, 58, 59, 60, 61, 62, 63},
        .oobfree = { {2, 38} }
    },
    /* End-of-list marker */
    {
        .useecc = -1,
    }
};

typedef struct {
dev_t dev;
ino_t ino;
int obj;
} objItem;

static objItem obj_list[MAX_OBJECTS];
static int n_obj = 0;
static int obj_id = YAFFS_NOBJECT_BUCKETS + 1;

static int nObjects = 0, nDirectories = 0, nPages = 0;

static int outFile;

static int error;

static int convert_endian = 0;

static int obj_compare(const void *a, const void * b)
{
objItem *oa, *ob;

oa = (objItem *)a;
ob = (objItem *)b;

    if(oa->dev < ob->dev) return -1;
    if(oa->dev > ob->dev) return 1;
    if(oa->ino < ob->ino) return -1;
    if(oa->ino > ob->ino) return 1;

return 0;
}

static void add_obj_to_list(dev_t dev, ino_t ino, int obj)
{
if(n_obj < MAX_OBJECTS)
{
  obj_list[n_obj].dev = dev;
  obj_list[n_obj].ino = ino;
  obj_list[n_obj].obj = obj;
  n_obj++;
  qsort(obj_list,n_obj,sizeof(objItem),obj_compare);

}
else
{
  // oops! not enough space in the object array
  fprintf(stderr,"Not enough space in object array/n");
  exit(2);
}
}

static int find_obj_in_list(dev_t dev, ino_t ino)
{
objItem *i = NULL;
objItem test;

test.dev = dev;
test.ino = ino;

if(n_obj > 0)
{
i = bsearch(&test,obj_list,n_obj,sizeof(objItem),obj_compare);
}

if(i)
{
return i->obj;
}
return -1;
}

static void yaffs_PutDataECC(const __u8 * data, unsigned char *oob_buf)
{
    unsigned char ecc_code[3];
    int eccsteps = chunkSize / 256;
    int eccidx = 0, datidx = 0, i;
    struct nand_oobinfo *oobsel;
    __u32 *oob_config;

oobsel = &oob_layout[layout_no];
oob_config = oobsel->eccpos; //LIUHAO: 24bytes的ECC在spare area中的位置

    for (; eccsteps; eccsteps--) {
        yaffs_ECCCalculate (&data[datidx], ecc_code);
  for (i = 0; i < 3; i++, eccidx++)
     oob_buf[oob_config[eccidx]] = ecc_code[i];
  datidx += 256;
    }
}

/* KSI:
* No big endian for now. This is left for a later time. The existing code
* is FUBAR.
*/
#if 0
/* This little function converts a little endian tag to a big endian tag.
* NOTE: The tag is not usable after this other than calculating the CRC
* with.
*/
static void little_to_big_endian(yaffs_Tags *tagsPtr)
{
#if 0 // FIXME NCB
yaffs_TagsUnion * tags = (yaffs_TagsUnion* )tagsPtr; // Work in bytes.
yaffs_TagsUnion temp;

    memset(&temp, 0, sizeof(temp));
    // Ick, I hate magic numbers.
    temp.asBytes[0] = ((tags->asBytes[2] & 0x0F) << 4) | ((tags->asBytes[1] & 0xF0) >> 4);
    temp.asBytes[1] = ((tags->asBytes[1] & 0x0F) << 4) | ((tags->asBytes[0] & 0xF0) >> 4);
    temp.asBytes[2] = ((tags->asBytes[0] & 0x0F) << 4) | ((tags->asBytes[2] & 0x30) >> 2) | ((tags->asBytes[3] & 0xC0) >> 6);
    temp.asBytes[3] = ((tags->asBytes[3] & 0x3F) << 2) | ((tags->asBytes[2] & 0xC0) >> 6);
    temp.asBytes[4] = ((tags->asBytes[6] & 0x03) << 6) | ((tags->asBytes[5] & 0xFC) >> 2);
    temp.asBytes[5] = ((tags->asBytes[5] & 0x03) << 6) | ((tags->asBytes[4] & 0xFC) >> 2);
    temp.asBytes[6] = ((tags->asBytes[4] & 0x03) << 6) | (tags->asBytes[7] & 0x3F);
    temp.asBytes[7] = (tags->asBytes[6] & 0xFC) | ((tags->asBytes[7] & 0xC0) >> 6);

    // Now copy it back.
    tags->asBytes[0] = temp.asBytes[0];
    tags->asBytes[1] = temp.asBytes[1];
    tags->asBytes[2] = temp.asBytes[2];
    tags->asBytes[3] = temp.asBytes[3];
    tags->asBytes[4] = temp.asBytes[4];
    tags->asBytes[5] = temp.asBytes[5];
    tags->asBytes[6] = temp.asBytes[6];
    tags->asBytes[7] = temp.asBytes[7];
#endif
}
#endif

static void nandmtd2_pt2buf(unsigned char *buf, yaffs_PackedTags2 *pt)
{
int i, j = 0, k, n;
//MODIFIED BY LIUHAO 2009-11-11
//unsigned char pt2_byte_buf[PT2_BYTES]; //Original
unsigned char pt2_byte_buf[PT2_BYTES] = {0};

*((unsigned int *) &pt2_byte_buf[0]) = pt->t.sequenceNumber;
*((unsigned int *) &pt2_byte_buf[4]) = pt->t.objectId;
*((unsigned int *) &pt2_byte_buf[8]) = pt->t.chunkId;
*((unsigned int *) &pt2_byte_buf[12]) = pt->t.byteCount;
pt2_byte_buf[16] = pt->ecc.colParity;
//MODIFIED BY LIUHAO 2009-11-11 START
#if 0
//Original
pt2_byte_buf[17] = pt->ecc.lineParity & 0xff;
pt2_byte_buf[18] = (pt->ecc.lineParity >> 8) & 0xff;
pt2_byte_buf[19] = (pt->ecc.lineParity >> 16) & 0xff;
pt2_byte_buf[20] = (pt->ecc.lineParity >> 24) & 0xff;
pt2_byte_buf[21] = pt->ecc.lineParityPrime & 0xff;
pt2_byte_buf[22] = (pt->ecc.lineParityPrime >> 8) & 0xff;
pt2_byte_buf[23] = (pt->ecc.lineParityPrime >> 16) & 0xff;
pt2_byte_buf[24] = (pt->ecc.lineParityPrime >> 24) & 0xff;
#else
pt2_byte_buf[20] = pt->ecc.lineParity & 0xff;
pt2_byte_buf[21] = (pt->ecc.lineParity >> 8) & 0xff;
pt2_byte_buf[22] = (pt->ecc.lineParity >> 16) & 0xff;
pt2_byte_buf[23] = (pt->ecc.lineParity >> 24) & 0xff;
pt2_byte_buf[24] = pt->ecc.lineParityPrime & 0xff;
pt2_byte_buf[25] = (pt->ecc.lineParityPrime >> 8) & 0xff;
pt2_byte_buf[26] = (pt->ecc.lineParityPrime >> 16) & 0xff;
pt2_byte_buf[27] = (pt->ecc.lineParityPrime >> 24) & 0xff;
#endif

k = oob_layout[layout_no].oobfree[j][0];
n = oob_layout[layout_no].oobfree[j][1];

if (n == 0) {
  fprintf(stderr, "No OOB space for tags");
  exit(-1);
}

for (i = 0; i < PT2_BYTES; i++) {
  if (n == 0) {
   j++;
   k = oob_layout[layout_no].oobfree[j][0];
   n = oob_layout[layout_no].oobfree[j][1];
   if (n == 0) {
    fprintf(stderr, "No OOB space for tags");
    exit(-1);
   }
  }
  buf[k++] = pt2_byte_buf[i];
  n--;
}
}

static int write_chunk(__u8 *data, __u32 objId, __u32 chunkId, __u32 nBytes)
{
yaffs_ExtendedTags t;
yaffs_PackedTags2 pt;

yaffs_PackedTags2TagsPart ptt; //ADDED BY LIUHAO 2009-11-11

//ADDED BY LIUHAO 2009-11-11
//unsigned char spare_buf[spareSize]; //Original
unsigned char spare_buf[spareSize] = {0};

error = write(outFile,data,chunkSize);
if(error < 0) return error;

yaffs_InitialiseTags(&t);

t.chunkId = chunkId;
// t.serialNumber = 0;
t.serialNumber = 1; // **CHECK**
t.byteCount = nBytes;
t.objectId = objId;

t.sequenceNumber = YAFFS_LOWEST_SEQUENCE_NUMBER;

// added NCB **CHECK**
t.chunkUsed = 1;

//ADDED BY LIUHAO 2009-11-11
//t.extraHeaderInfoAvailable = 1;

/* KSI: Broken anyway -- e.g. &t is pointer to a wrong type... */
#if 0
if (convert_endian)
{
little_to_big_endian(&t);
}
#endif

//MODIFIED BY LIUHAO 2009-11-11 START
#if 0
yaffs_PackTags2(&pt,&t); //Original
#else
memset(&pt, 0, sizeof(yaffs_PackedTags2));
yaffs_PackTags2TagsPart(&pt.t,&t);
yaffs_ECCCalculateOther(
  (unsigned char *)&pt.t,
  sizeof(yaffs_PackedTags2TagsPart),
  &pt.ecc);
#endif
//MODIFIED BY LIUHAO 2009-11-11 END

    memset(spare_buf, 0xff, sizeof(spare_buf));

    if (layout_no == 0) {
  memcpy(spare_buf, &pt, sizeof(yaffs_PackedTags2));
} else {
  nandmtd2_pt2buf(spare_buf, &pt);
}

yaffs_PutDataECC(data, &spare_buf[0]);

nPages++;

return write(outFile,spare_buf,spareSize);
}

#define SWAP32(x)   ((((x) & 0x000000FF) << 24) | /
                     (((x) & 0x0000FF00) << 8 ) | /
                     (((x) & 0x00FF0000) >> 8 ) | /
                     (((x) & 0xFF000000) >> 24))

#define SWAP16(x)   ((((x) & 0x00FF) << 8) | /
                     (((x) & 0xFF00) >> 8))

/* KSI: Removed for now. TBD later when the proper util (from scratch) is written */
#if 0
// This one is easier, since the types are more standard. No funky shifts here.
static void object_header_little_to_big_endian(yaffs_ObjectHeader* oh)
{
    oh->type = SWAP32(oh->type); // GCC makes enums 32 bits.
    oh->parentObjectId = SWAP32(oh->parentObjectId); // int
    oh->sum__NoLongerUsed = SWAP16(oh->sum__NoLongerUsed); // __u16 - Not used, but done for completeness.
    // name = skip. Char array. Not swapped.
    oh->yst_mode = SWAP32(oh->yst_mode);
#ifdef CONFIG_YAFFS_WINCE // WinCE doesn't implement this, but we need to just in case.
    // In fact, WinCE would be *THE* place where this would be an issue!
    oh->notForWinCE[0] = SWAP32(oh->notForWinCE[0]);
    oh->notForWinCE[1] = SWAP32(oh->notForWinCE[1]);
    oh->notForWinCE[2] = SWAP32(oh->notForWinCE[2]);
    oh->notForWinCE[3] = SWAP32(oh->notForWinCE[3]);
    oh->notForWinCE[4] = SWAP32(oh->notForWinCE[4]);
#else
    // Regular POSIX.
    oh->yst_uid = SWAP32(oh->yst_uid);
    oh->yst_gid = SWAP32(oh->yst_gid);
    oh->yst_atime = SWAP32(oh->yst_atime);
    oh->yst_mtime = SWAP32(oh->yst_mtime);
    oh->yst_ctime = SWAP32(oh->yst_ctime);
#endif

    oh->fileSize = SWAP32(oh->fileSize); // Aiee. An int... signed, at that!
    oh->equivalentObjectId = SWAP32(oh->equivalentObjectId);
    // alias - char array.
    oh->yst_rdev = SWAP32(oh->yst_rdev);

#ifdef CONFIG_YAFFS_WINCE
    oh->win_ctime[0] = SWAP32(oh->win_ctime[0]);
    oh->win_ctime[1] = SWAP32(oh->win_ctime[1]);
    oh->win_atime[0] = SWAP32(oh->win_atime[0]);
    oh->win_atime[1] = SWAP32(oh->win_atime[1]);
    oh->win_mtime[0] = SWAP32(oh->win_mtime[0]);
    oh->win_mtime[1] = SWAP32(oh->win_mtime[1]);
    oh->roomToGrow[0] = SWAP32(oh->roomToGrow[0]);
    oh->roomToGrow[1] = SWAP32(oh->roomToGrow[1]);
    oh->roomToGrow[2] = SWAP32(oh->roomToGrow[2]);
    oh->roomToGrow[3] = SWAP32(oh->roomToGrow[3]);
    oh->roomToGrow[4] = SWAP32(oh->roomToGrow[4]);
    oh->roomToGrow[5] = SWAP32(oh->roomToGrow[5]);
#else
    oh->roomToGrow[0] = SWAP32(oh->roomToGrow[0]);
    oh->roomToGrow[1] = SWAP32(oh->roomToGrow[1]);
    oh->roomToGrow[2] = SWAP32(oh->roomToGrow[2]);
    oh->roomToGrow[3] = SWAP32(oh->roomToGrow[3]);
    oh->roomToGrow[4] = SWAP32(oh->roomToGrow[4]);
    oh->roomToGrow[5] = SWAP32(oh->roomToGrow[5]);
    oh->roomToGrow[6] = SWAP32(oh->roomToGrow[6]);
    oh->roomToGrow[7] = SWAP32(oh->roomToGrow[7]);
    oh->roomToGrow[8] = SWAP32(oh->roomToGrow[8]);
    oh->roomToGrow[9] = SWAP32(oh->roomToGrow[9]);
    oh->roomToGrow[10] = SWAP32(oh->roomToGrow[10]);
    oh->roomToGrow[11] = SWAP32(oh->roomToGrow[11]);
#endif
}
#endif

static int write_object_header(int objId, yaffs_ObjectType t, struct stat *s, int parent, const char *name, int equivalentObj, const char * alias)
{
__u8 bytes[chunkSize];

yaffs_ObjectHeader *oh = (yaffs_ObjectHeader *)bytes;

memset(bytes,0xff,sizeof(bytes));

oh->type = t;

oh->parentObjectId = parent;

strncpy(oh->name,name,YAFFS_MAX_NAME_LENGTH);

if(t != YAFFS_OBJECT_TYPE_HARDLINK)
{
  oh->yst_mode = s->st_mode;
  oh->yst_uid = s->st_uid;
// NCB 12/9/02  oh->yst_gid = s->yst_uid;
  oh->yst_gid = s->st_gid;
  oh->yst_atime = s->st_atime;
  oh->yst_mtime = s->st_mtime;
  oh->yst_ctime = s->st_ctime;
  oh->yst_rdev = s->st_rdev;
}

if(t == YAFFS_OBJECT_TYPE_FILE)
{
  oh->fileSize = s->st_size;
}

if(t == YAFFS_OBJECT_TYPE_HARDLINK)
{
  oh->equivalentObjectId = equivalentObj;
}

if(t == YAFFS_OBJECT_TYPE_SYMLINK)
{
  strncpy(oh->alias,alias,YAFFS_MAX_ALIAS_LENGTH);
}

/* KSI: FUBAR. Left for a leter time. */
#if 0
if (convert_endian)
{
object_header_little_to_big_endian(oh);
}
#endif

return write_chunk(bytes,objId,0,0xffff);

}

static int process_directory(int parent, const char *path)
{

DIR *dir;
struct dirent *entry;

nDirectories++;

dir = opendir(path);

if(dir)
{
  while((entry = readdir(dir)) != NULL)
  {

   /* Ignore . and .. */
   if(strcmp(entry->d_name,".") &&
      strcmp(entry->d_name,".."))
    {
     char full_name[500];
    struct stat stats;
    int equivalentObj;
    int newObj;

    sprintf(full_name,"%s/%s",path,entry->d_name);

    lstat(full_name,&stats);

    if(S_ISLNK(stats.st_mode) ||
        S_ISREG(stats.st_mode) ||
        S_ISDIR(stats.st_mode) ||
        S_ISFIFO(stats.st_mode) ||
        S_ISBLK(stats.st_mode) ||
        S_ISCHR(stats.st_mode) ||
        S_ISSOCK(stats.st_mode))
    {

     newObj = obj_id++;
     nObjects++;

     printf("Object %d, %s is a ",newObj,full_name);

     /* We're going to create an object for it */
     if((equivalentObj = find_obj_in_list(stats.st_dev, stats.st_ino)) > 0)
     {
      /* we need to make a hard link */
      printf("hard link to object %d/n",equivalentObj);
      error = write_object_header(newObj, YAFFS_OBJECT_TYPE_HARDLINK, &stats, parent, entry->d_name, equivalentObj, NULL);
     }
     else
     {

      add_obj_to_list(stats.st_dev,stats.st_ino,newObj);

      if(S_ISLNK(stats.st_mode))
      {

       char symname[500];

       memset(symname,0, sizeof(symname));

       readlink(full_name,symname,sizeof(symname) -1);

       printf("symlink to /"%s/"/n",symname);
       error = write_object_header(newObj, YAFFS_OBJECT_TYPE_SYMLINK, &stats, parent, entry->d_name, -1, symname);

      }
      else if(S_ISREG(stats.st_mode))
      {
       printf("file, ");
       error = write_object_header(newObj, YAFFS_OBJECT_TYPE_FILE, &stats, parent, entry->d_name, -1, NULL);

       if(error >= 0)
       {
        int h;
        __u8 bytes[chunkSize];
        int nBytes;
        int chunk = 0;

        h = open(full_name,O_RDONLY);
        if(h >= 0)
        {
         memset(bytes,0xff,sizeof(bytes));
         while((nBytes = read(h,bytes,sizeof(bytes))) > 0)
         {
          chunk++;
          write_chunk(bytes,newObj,chunk,nBytes);
          memset(bytes,0xff,sizeof(bytes));
         }
         if(nBytes < 0)
            error = nBytes;

         printf("%d data chunks written/n",chunk);
                close(h);
        }
        else
        {
         perror("Error opening file");
        }

       }

      }
      else if(S_ISSOCK(stats.st_mode))
      {
       printf("socket/n");
       error = write_object_header(newObj, YAFFS_OBJECT_TYPE_SPECIAL, &stats, parent, entry->d_name, -1, NULL);
      }
      else if(S_ISFIFO(stats.st_mode))
      {
       printf("fifo/n");
       error = write_object_header(newObj, YAFFS_OBJECT_TYPE_SPECIAL, &stats, parent, entry->d_name, -1, NULL);
      }
      else if(S_ISCHR(stats.st_mode))
      {
       printf("character device/n");
       error = write_object_header(newObj, YAFFS_OBJECT_TYPE_SPECIAL, &stats, parent, entry->d_name, -1, NULL);
      }
      else if(S_ISBLK(stats.st_mode))
      {
       printf("block device/n");
       error = write_object_header(newObj, YAFFS_OBJECT_TYPE_SPECIAL, &stats, parent, entry->d_name, -1, NULL);
      }
      else if(S_ISDIR(stats.st_mode))
      {
       printf("directory/n");
       error = write_object_header(newObj, YAFFS_OBJECT_TYPE_DIRECTORY, &stats, parent, entry->d_name, -1, NULL);
       process_directory(newObj,full_name);
      }
     }
    }
    else
    {
     printf(" we don't handle this type/n");
    }
   }
  }
  closedir(dir);
}

return 0;

}

void usage(void)
{
printf("usage: mkyaffs2image layout# dir image_file [convert]/n");
printf(" layout# NAND OOB layout # (0 - raw, 1 - nand_oob_64)/n");
printf(" dir the directory tree to be converted/n");
printf(" image_file the output file to hold the image/n");
printf(" 'convert' make a big-endian img on a little-endian machine. BROKEN !/n");
exit(1);
}

int main(int argc, char *argv[])
{
struct stat stats;
int i;

printf("mkyaffs2image: image building tool for YAFFS2 built "__DATE__"/n");

if ((argc < 4) || (sscanf(argv[1], "%u", &layout_no) != 1))
{
usage();
}

i = 0;

while (oob_layout[i].useecc != -1)
         i++;

        if (layout_no >= i)
                usage();

if ((argc == 5) && (!strncmp(argv[4], "convert", strlen("convert"))))
{
                fprintf (stderr, "WARNING: ENDIAN CONVERSION IS BROKEN/n");
         /* KSI: Broken as of now. TBD. Fail. */
         usage();
                convert_endian = 1;
        }

if(stat(argv[2],&stats) < 0)
{
  printf("Could not stat %s/n",argv[2]);
  exit(1);
}

if(!S_ISDIR(stats.st_mode))
{
  printf(" %s is not a directory/n",argv[2]);
  exit(1);
}

outFile = open(argv[3],O_CREAT | O_TRUNC | O_WRONLY, S_IREAD | S_IWRITE);

if(outFile < 0)
{
  printf("Could not open output file %s/n",argv[3]);
  exit(1);
}

printf("Processing directory %s into image file %s/n",argv[2],argv[3]);
error = write_object_header(1, YAFFS_OBJECT_TYPE_DIRECTORY, &stats, 1,"", -1, NULL);

if(error)
error = process_directory(YAFFS_OBJECTID_ROOT,argv[2]);

close(outFile);

if(error < 0)
{
  perror("operation incomplete");
  exit(1);
}
else
{
  printf("Operation complete./n"
         "%d objects in %d directories/n"
         "%d NAND pages/n",nObjects, nDirectories, nPages);
}

close(outFile);

exit(0);
}

PART2 About 16bytes OOB

另外，下面用关键性的数据结构简单展示一下16bytes OOB区内的组织格式：

typedef struct {
unsigned chunkId:20;
unsigned serialNumber:2;
unsigned byteCountLSB:10;
unsigned objectId:18;
unsigned ecc:12;
unsigned byteCountMSB:2;
} yaffs_Tags;

//LIUHAO: yaffs_TagsUnion共用体，方便实现对yaffs_Tags中数据的处理。
typedef union {
yaffs_Tags asTags;
__u8 asBytes[8];
} yaffs_TagsUnion;

//LIUHAO: 512bytes data + 16bytes spare时spare区中的数据格式
//其中ecc1[3]为512bytes前半区的ecc校验码
// ecc2[3]为512bytes后半区的ecc校验码

/* Spare structure for YAFFS1 */
typedef struct {
__u8 tagByte0;
__u8 tagByte1;
__u8 tagByte2;
__u8 tagByte3;
__u8 pageStatus; /* set to 0 to delete the chunk */
__u8 blockStatus;
__u8 tagByte4;
__u8 tagByte5;
__u8 ecc1[3];
__u8 tagByte6;
__u8 tagByte7;
__u8 ecc2[3];
} yaffs_Spare;

总结：

对于未知的领域和问题，唯独我们坚持，才会最终得到正确的答案。一句话说得好：人类最伟大的品质在于坚持，所有的梦想和目标都会因些而实现。

原文地址 http://blog.csdn.net/itismine/archive/2009/11/11/4799770.aspx