Eboot 中给nandflash分区实现.doc

Eboot 中给nandflash分区实现 提到分区就不得不提到MBR，不得不提到分区表。什么是MBR硬盘的0柱面、0磁头、1扇区称为主引导扇区，NANDFLASH由BLOCK和Sector组成，所以NANDFLASH的第0 BLOCK，第1 Sector为主引导扇区，FDISK程序写到该扇区的内容称为主引导记录（MBR）。该记录占用512个字节，它用于硬盘启动时将系统控制权交给用户指定的，并在分区表中登记了的某个操作系统区。MBR的组成一个扇区的硬盘主引导记录MBR由如图6-15所示的4个部分组成。主引导程序（偏移地址0000H-0088H），它负责从活动分区中装载，并运行系统引导程序。出错信息数据区，偏移地址0089H-00E1H为出错信息，00E2H-01BDH全为0字节。分区表（DPT,Disk Partition Table）含4个分区项，偏移地址01BEH-01FDH,每个分区表项长16个字节，共64字节为分区项1、分区项2、分区项3、分区项4。结束标志字，偏移地址01FE-01FF的2个字节值为结束标志55AA,如果该标志错误系统就不能启动。图6-15 MBR的组成结构图MBR中的分区信息结构 占用512个字节的MBR中，偏移地址01BEH-01FDH的64个字节，为4个分区项内容（分区信息表）。它是由磁盘介质类型及用户在使用 FDISK定义分区说确定的。在实际应用中，FDISK对一个磁盘划分的主分区可少于4个，但最多不超过4个。每个分区表的项目是16个字节，其内容含义 如表6-19所示。表6-19 分区项表（16字节）内容及含义EBOOT中对NAND分区主要代码，eboot目录下的fmd.cpp文件，与NAND驱动基本相同，所以，要对NAND进行分区，就得对NAND驱动非常熟悉。透彻了解。然后就是E:WINCE500PUBLICCOMMONOAKDRIVERSETHDBGBOOTPARTbootpart.cpp文件了。该文件主要通过调用NANDFLASH的读写操作来写入MBR，也是今天主要的分析对象。主要函数。/* BP_OpenPartition * * Opens/creates a partition depending on the creation flags. If it is opening * and the partition has already been opened, then it returns a handle to the * opened partition. Otherwise, it loads the state information of that partition * into memory and returns a handle. * * ENTRY * dwStartSector - Logical sector to start the partition. NEXT_FREE_LOC if none * specified. Ignored if opening existing partition. * dwNumSectors - Number of logical sectors of the partition. USE_REMAINING_SPACE * to indicate to take up the rest of the space on the flash for that partition (should * only be used when creating extended partitions). This parameter is ignored * if opening existing partition. * dwPartType - Type of partition to create/open. * fActive - TRUE indicates to create/open the active partition. FALSE for * inactive. * dwCreationFlags - PART_CREATE_NEW to create only. Fail if it already * exists. PART_OPEN_EXISTING to open only. Fail if it doesnt exist. * PART_OPEN_ALWAYS creates if it does not exist and opens if it * does exist. * * EXIT * Handle to the partition on success. INVALID_HANDLE_VALUE on error. */HANDLE BP_OpenPartition(DWORD dwStartSector, DWORD dwNumSectors, DWORD dwPartType, BOOL fActive, DWORD dwCreationFlags)注：示例代码为本人EBOOT中分区实现源码（WINCE5.0+S3C2440+128MNAND,MBR写在第4个BLOCK，分一个BINFS格式分区和一个FAT格式分区）。BOOL WriteRegionsToBootMedia(DWORD dwImageStart, DWORD dwImageLength, DWORD dwLaunchAddr)在把SDRAM中的NK烧写到NAND中去之前，先创建一个BINFS分区。hPart = BP_OpenPartition( (NK_START_BLOCK+1)*PAGES_PER_BLOCK, / next block of MBR BINFS_BLOCK*PAGES_PER_BLOCK,/SECTOR_TO_BLOCK_SIZE(FILE_TO_SECTOR_SIZE(dwBINFSPartLength)*PAGES_PER_BLOCK, /align to block PART_BINFS, TRUE, PART_OPEN_ALWAYS);第一个参数分区的起始sector 为(NK_START_BLOCK+1)*PAGES_PER_BLOCK，第二个参数分区的结束 sector为BINFS_BLOCK*PAGES_PER_BLOCK，第三个参数分区的格式为PART_BINFS，即BINFS格式，第四个参数指示该分区为活动分区，fActive = TURE，第五个参数PART_OPEN_ALWAYS指示如果分区不存在就创建该分区，存在就OPEN该分区，返回分区句柄。HANDLE BP_OpenPartition(DWORD dwStartSector, DWORD dwNumSectors, DWORD dwPartType, BOOL fActive, DWORD dwCreationFlags) DWORD dwPartIndex; BOOL fExists; ASSERT (g_pbMBRSector); if (!IsValidMBR() DWORD dwFlags = 0; /fly RETAILMSG(1, (TEXT(BP_OpenPartition: dwStartSector=0x%x ,dwNumSectors= 0x%x.,dwPartType = 0x%xrn), dwStartSector, dwNumSectors,dwPartType); if (dwCreationFlags = PART_OPEN_EXISTING) RETAILMSG(1, (TEXT(OpenPartition: Invalid MBR. Cannot open existing partition 0x%x.rn), dwPartType); return INVALID_HANDLE_VALUE; RETAILMSG(1, (TEXT(OpenPartition: Invalid MBR. Formatting flash.rn); if (g_FlashInfo.flashType = NOR) dwFlags |= FORMAT_SKIP_BLOCK_CHECK; /fly RETAILMSG(1, (TEXT(BP_LowLevelFormat: g_pbMBRSector=0x%x, g_dwMBRSectorNum= 0x%x.rn), *g_pbMBRSector, g_dwMBRSectorNum); BP_LowLevelFormat (SECTOR_TO_BLOCK(dwStartSector), SECTOR_TO_BLOCK(dwNumSectors), dwFlags); dwPartIndex = 0; fExists = FALSE; else fExists = GetPartitionTableIndex(dwPartType, fActive, &dwPartIndex); RETAILMSG(1, (TEXT(OpenPartition: Partition Exists=0x%x for part 0x%x.rn), fExists, dwPartType); if (fExists) / Partition was found. if (dwCreationFlags = PART_CREATE_NEW) return INVALID_HANDLE_VALUE; if (g_partStateTabledwPartIndex.pPartEntry = NULL) / Open partition. If this is the boot section partition, then file pointer starts after MBR g_partStateTabledwPartIndex.pPartEntry = (PPARTENTRY)(g_pbMBRSector + PARTTABLE_OFFSET + sizeof(PARTENTRY)*dwPartIndex); g_partStateTabledwPartIndex.dwDataPointer = 0; if ( dwNumSectors g_partStateTabledwPartIndex.pPartEntry-Part_TotalSectors ) return CreatePartition (dwStartSector, dwNumSectors, dwPartType, fActive, dwPartIndex); else return (HANDLE)&g_partStateTabledwPartIndex; else / If there are already 4 partitions, or creation flag specified OPEN_EXISTING, fail. if (dwPartIndex = NUM_PARTS) | (dwCreationFlags = PART_OPEN_EXISTING) return INVALID_HANDLE_VALUE; / Create new partition return CreatePartition (dwStartSector, dwNumSectors, dwPartType, fActive, dwPartIndex); return INVALID_HANDLE_VALUE; 进入函数，首先做的事就是检测MBR的有效性。通过函数IsValidMBR（）实现。检测MBR的有效性，首先要知道MBR保存在哪里，前面说过NANDFLASH的第0 BLOCK，第1 Sector为主引导扇区，也就是MBR，但是NAND如果被当作启动芯片，地址一般被BOOTLOADER代码占据，MBR只有放在后面的BLOCK中。所以我把第0 个BLOCK放NBOOT，第1个BLOCK放TOC，第2个BLOCK放EBOOT，第3个BLOCK保留，第4个BLOCK就放MBR。static BOOL IsValidMBR() / Check to see if the MBR is valid / MBR block is always located at logical sector 0 g_dwMBRSectorNum = GetMBRSectorNum(); RETAILMSG (1, (TEXT(IsValidMBR: MBR sector = 0x%xrn), g_dwMBRSectorNum); if (g_dwMBRSectorNum = INVALID_ADDR) | !FMD_ReadSector (g_dwMBRSectorNum, g_pbMBRSector, NULL, 1) RETAILMSG (1, (TEXT(IsValidMBR-return FALSE-rn); return FALSE; return (g_pbMBRSector0 = 0xE9) & (g_pbMBRSector1 = 0xfd) & (g_pbMBRSector2 = 0xff) & (g_pbMBRSectorSECTOR_SIZE_FS-2 = 0x55) & (g_pbMBRSectorSECTOR_SIZE_FS-1 = 0xAA); IsValidMBR()实现的第一行就是给全局变量g_dwMBRSectorNum 赋值，显而易见，g_dwMBRSectorNum就是指示保存MBR的那个Sector了。g_dwMBRSectorNum = GetMBRSectorNum(); /是获得保存MBR的那个Sectorstatic DWORD GetMBRSectorNum () DWORD dwBlockNum = 3, dwSector = 0; SectorInfo si; while (dwBlockNum 0)然后确定BLOCK是否可使用的BLOCK，最后通si.dwReserved1 = 0来判断是不是选择这个Sector来保存MBR。IsValidMBR（）中还有一个重要的结构就是g_pbMBRSector数组，它就是MBR了。函数返回时，MBR必须符合下列记录。 return (g_pbMBRSector0 = 0xE9) & (g_pbMBRSector1 = 0xfd) & (g_pbMBRSector2 = 0xff) & (g_pbMBRSectorSECTOR_SIZE_FS-2 = 0x55) & (g_pbMBRSectorSECTOR_SIZE_FS-1 = 0xAA);可以看到只有开始三个字节为0XE9,FD,FF，当然，还有熟悉的结束标志符0X55AA。如果没有检测到MBR，则先对NANDFLASH进行低级格式化。BP_LowLevelFormat (SECTOR_TO_BLOCK(dwStartSector), SECTOR_TO_BLOCK(dwNumSectors), dwFlags);再创建分区，CreatePartition (dwStartSector, dwNumSectors, dwPartType, fActive, dwPartIndex);。BOOL BP_LowLevelFormat(DWORD dwStartBlock, DWORD dwNumBlocks, DWORD dwFlags) dwNumBlocks = min (dwNumBlocks, g_FlashInfo.dwNumBlocks); RETAILMSG(1,(TEXT(fly:Enter LowLevelFormat 0x%x, 0x%x.rn), dwStartBlock,dwNumBlocks);/ dwStartBlock + dwNumBlocks - 1); / Erase all the flash blocks. if (!EraseBlocks(dwStartBlock, dwNumBlocks, dwFlags) return(FALSE); / Determine first good starting block while (IS_BLOCK_UNUSABLE (dwStartBlock) & dwStartBlock = g_FlashInfo.dwNumBlocks) RETAILMSG(1,(TEXT(BP_LowLevelFormat: no good blocksrn); return FALSE; / MBR goes in the first sector of the starting block. This will be logical sector 0. g_dwMBRSectorNum = dwStartBlock * g_FlashInfo.wSectorsPerBlock; RETAILMSG(1,(TEXT(fly:g_dwMBRSectorNum=%drn),g_dwMBRSectorNum); / Create an MBR. CreateMBR(); return(TRUE);在对NANDFLASH进行低格时，主要对坏块的处理。if (!EraseBlocks(dwStartBlock, dwNumBlocks, dwFlags)检测每一个Sector，每个BLOCK只要有一个Sector不能读写这个块都会被处理成坏块，这样才能保证系统的稳定性。在函数的最后调用了 CreateMBR();来创建一个MBR。static BOOL CreateMBR() / This, plus a valid partition table, is all the CE partition manager needs to recognize / the MBR as valid. It does not contain boot code. memset (g_pbMBRSector, 0xff, g_FlashInfo.wDataBytesPerSector); g_pbMBRSector0 = 0xE9; g_pbMBRSector1 = 0xfd; g_pbMBRSector2 = 0xff; g_pbMBRSectorSECTOR_SIZE_FS-2 = 0x55; g_pbMBRSectorSECTOR_SIZE_FS-1 = 0xAA; / Zero out partition table so that mspart treats entries as empty. memset (g_pbMBRSector+PARTTABLE_OFFSET, 0, sizeof(PARTENTRY) * NUM_PARTS); return WriteMBR(); 当然。因为还没有进行分区，这里写入的MBR分区表部分是空的。static BOOL WriteMBR() DWORD dwMBRBlockNum = g_dwMBRSectorNum / g_FlashInfo.wSectorsPerBlock; /dwMBRBlockNum = 1 ; RETAILMSG(1, (TEXT(WriteMBR: MBR block = 0x%x,g_dwMBRSectorNum = 0x%x.rn), dwMBRBlockNum,g_dwMBRSectorNum); memset (g_pbBlock, 0xff, g_dwDataBytesPerBlock); memset (g_pSectorInfoBuf, 0xff, sizeof(SectorInfo) * g_FlashInfo.wSectorsPerBlock); / No need to check return, since a failed read means data hasnt been written yet. ReadBlock (dwMBRBlockNum, g_pbBlock, g_pSectorInfoBuf); if (!FMD_EraseBlock (dwMBRBlockNum) RETAILMSG (1, (TEXT(CreatePartition: error erasing block 0x%xrn), dwMBRBlockNum); return FALSE; memcpy (g_pbBlock + (g_dwMBRSectorNum % g_FlashInfo.wSectorsPerBlock) * g_FlashInfo.wDataBytesPerSector, g_pbMBRSector, g_FlashInfo.wDataBytesPerSector); g_pSectorInfoBuf-bOEMReserved &= OEM_BLOCK_READONLY; g_pSectorInfoBuf-wReserved2 &= SECTOR_WRITE_COMPLETED; g_pSectorInfoBuf-dwReserved1 = 0; RETAILMSG(1, (TEXT(fly:WriteMBR: MBR block = 0x%x.rn), dwMBRBlockNum); if (!WriteBlock (dwMBRBlockNum, g_pbBlock, g_pSectorInfoBuf) RETAILMSG (1, (TEXT(CreatePartition: could not write to block 0x%xrn), dwMBRBlockNum); return FALSE; return TRUE; 在WriteMBR()函数中，就写入了判断MBR 的一些标志到BLOCK， g_pSectorInfoBuf-bOEMReserved &= OEM_BLOCK_READONLY; g_pSectorInfoBuf-wReserved2 &= SECTOR_WRITE_COMPLETED; g_pSectorInfoBuf-dwReserved1 = 0;Wince系统启动时，具体是NANDFLASH驱动加载成功后，MOUNT文件系统到NANDFLASH之前，也会通过读取这些SectorInfo来得到MBR 保存的BLOCK，进而读取MBR，获得分区信息，从而把各分区MOUNT到相应文件系统。格式化完成，MBR也写入成功后就可以开始新建分区了。/* CreatePartition * * Creates a new partition. If it is a boot section partition, then it formats * flash. * * ENTRY * dwStartSector - Logical sector to start the partition. NEXT_FREE_LOC if * none specified. * dwNumSectors - Number of logical sectors of the partition. USE_REMAINING_SPACE * to indicate to take up the rest of the space on the flash for that partition. * dwPartType - Type of partition to create. * fActive - TRUE indicates to create the active partition. FALSE for * inactive. * dwPartIndex - Index of the partition entry on the MBR * * EXIT * Handle to the partition on success. INVALID_HANDLE_VALUE on error. */static HANDLE CreatePartition (DWORD dwStartSector, DWORD dwNumSectors, DWORD dwPartType, BOOL fActive, DWORD dwPartIndex) DWORD dwBootInd = 0; RETAILMSG(1, (TEXT(CreatePartition: Enter CreatePartition for 0x%x.rn), dwPartType); if (fActive) dwBootInd |= PART_IND_ACTIVE; if (dwPartType = PART_BOOTSECTION | dwPartType = PART_BINFS | dwPartType = PART_XIP) dwBootInd |= PART_IND_READ_ONLY; / If start sector is invalid, it means find next free sector if (dwStartSector = NEXT_FREE_LOC) dwStartSector = FindFreeSector(); if (dwStartSector = INVALID_ADDR) RETAILMSG(1, (TEXT(CreatePartition: cant find free sector.rn); return INVALID_HANDLE_VALUE; / Start extended partition on a block boundary if (dwPartType = PART_EXTENDED) & (dwStartSector % g_FlashInfo.wSectorsPerBlock) dwStartSector = (dwStartSector / g_FlashInfo.wSectorsPerBlock + 1) * g_FlashInfo.wSectorsPerBlock; / If num sectors is invalid, fill the rest of the space up if (dwNumSectors = USE_REMAINING_SPACE) DWORD dwLastLogSector = LastLogSector(); if (dwLastLogSector = INVALID_ADDR) return INVALID_HANDLE_VALUE; / Determine the number of blocks to reserve for the FAL compaction when creating an extended partition. DWORD dwReservedBlocks = g_FlashInfo.dwNumBlocks / PERCENTAGE_OF_MEDIA_TO_RESERVE; if(dwReservedBlocks = g_FlashInfo.dwNumBlocks / PERCENTAGE_OF_MEDIA_TO_RESERVE) MINIMUM_FLASH_BLOCKS_TO_RESERVE) dwReservedBlocks = MINIMUM_FLASH_BLOCKS_TO_RESERVE; dwNumSectors = dwLastLogSector - dwStartSector + 1 - dwReservedBlocks * g_FlashInfo.wSectorsPerBlock; if (!AreSectorsFree (dwStartSector, dwNumSectors) RETAILMSG (1, (TEXT(fly:CreatePartition: sectors 0x%x, 0x%x requested are out of range or taken by another partitionrn), dwStartSector, dwNumSectors); return INVALID_HANDLE_VALUE; RETAILMSG(1, (TEXT(CreatePartition: Start = 0x%x, Num = 0x%x.rn), dwStartSector, dwNumSectors); AddPartitionTableEntry (dwPartIndex, dwStartSector, dwNumSectors, (BYTE)dwPartType, (BYTE)dwBootInd); if (dwBootInd & PART_IND_READ_ONLY) if (!WriteLogicalNumbers (dwStartSector, dwNumSectors, TRUE) RETAILMSG(1, (TEXT(CreatePartition: cant mark sector info.rn); return INVALID_HANDLE_VALUE; if (!WriteMBR() return INVALID_HANDLE_VALUE; g_partStateTabledwPartIndex.pPartEntry = (PPARTENTRY)(g_pbMBRSector + PARTTABLE_OFFSET + sizeof(PARTENTRY)*dwPartIndex); g_partStateTabledwPartIndex.dwDataPointer = 0; return (HANDLE)&g_partStateTabledwPartIndex; 如果第二个参数为1，则视为将余下的所有空间划为一个分区。LastLogSector();函数获得最后一个逻辑Sector。static DWORD LastLogSector() if (g_dwLastLogSector) return g_dwLastLogSector; DWORD dwMBRBlock = g_dwMBRSectorNum / g_FlashInfo.wSectorsPerBlock; DWORD dwUnusableBlocks = dwMBRBlock; for (DWORD i = dwMBRBlock; i g_FlashInfo.dwNumBlocks; i+) if (IS_BLOCK_UNUSABLE (i) dwUnusableBlocks+; g_dwLastLogSector = (g_FlashInfo.dwNumBlocks - dwUnusableBlocks) * g_FlashInfo.wSectorsPerBlock - 1; RETAILMSG(1, (TEXT(fly:LastLo