mkfs.fat 将 BPB 中的 FAT32 字段保留为空值

Question

我有一个问题，mkfs.fat 使用参数 -F 32 将 FAT32 字段保留为空。我正在创建自己的引导加载程序并尝试从 EFI 分区读取，但不知何故这些值处于空值。 FAT32 字段之前的字段设置正确。为了从磁盘读取，我使用 ATA PIO 模式。

这是我的 BPB 结构：

#pragma pack(1)

typedef struct {
uint8_t jmpnop[3];
char OEMIdentifier[8];
uint16_t BytesPerSector;
uint8_t SectorsPerCluster;
uint16_t NumberOfReservedSectors;
uint8_t NumberOfFATs;
uint16_t NumberOfRootDirectories;
uint16_t TotalSectors;
uint8_t Media;
uint16_t Reserved;
uint16_t SectorsPerTrack;
uint16_t NumberOfHeads;
uint32_t HiddenSectors;
uint32_t LargeSectorCount;
}  BPB;

typedef struct {
BPB base;
uint32_t SectorsPerFat;
uint16_t Flags;
uint16_t Version;
uint32_t ClusterNumberRootDir;
uint16_t SectorNumberFSInfo;
uint16_t SectorNumberBackupBootSector;
uint8_t Reserved[12];
uint8_t DriveNumber;
uint8_t Reserved2;
uint8_t Signature;
uint32_t VolumeID;
uint8_t VolumeLabel[11];
char SystemIdentifier[8]; //Specs says never trust
} BPB_FAT32;

我尝试向 mkfs.fat 添加详细参数，看起来一切都很好

Answer 1

更新，也许是我的ata pio模式驱动程序的问题，因为磁盘似乎没有读取整个扇区。 这是我的 ata pio 模式驱动程序的读取功能：

uint8_t Read(Disk *d,uint32_t LBA,uint16_t num,uint32_t addr)
{
    //check if LBA48 is supported,if yes it will use LBA48 mode otherwise it will use LBA28 mode
    if(d->LBA48 == 1)
    {
        if(d->dev == MASTER_DRIVE)
        {
            outb(d->bus+DRIVE,0x40);
        }
        else {
            outb(d->bus+DRIVE,0x50);
        }
        while(((inb(d->bus) >> 7) & 1) != 0);
        uint16_t LBAmiddle =   (uint16_t)(LBA >> 16) & 0xFFFF;
        outw(d->bus+SECTOR_COUNT_REGISTER, num);
        outw(d->bus+LBAlo,(uint16_t)LBA & 0xFFFF);
        if(LBAmiddle > 0) outw(d->bus+LBAmid,LBAmiddle);
        outb(d->bus+COMMAND,READ_LBA48);
    }
    else {
        if(d->dev == MASTER_DRIVE)
        {
            outb(d->bus+DRIVE,0xE0);
        }
        else {
            outb(d->bus+DRIVE,0xF0);
        }
        while(((inb(d->bus) >> 7) & 1) != 0);
        outw(d->bus+SECTOR_COUNT_REGISTER, num);
        outb(d->bus+LBAlo,(uint8_t)LBA & 0xFF);
        outw(d->bus+LBAmid,(uint8_t)(LBA << 8) & 0xFF);
        outw(d->bus+LBAhi, (uint8_t)(LBA << 16) & 0xFF);
        outb(d->bus+COMMAND,READ_LBA28);
    }
    //wait until drive is ready to send data and check for error
    ATAsleep(d->bus);
    if(error == 1)
    {
        return inb(d->bus+ERROR_REGISTER);
    }

    //return the data
    //the driver count that the user has drive with 512 bytes sector size
    uint16_t *data = (uint16_t*)addr;
    for(int i = 0; i < (256*num);i++)
    {
        data[i] = inw(d->bus+DATA_REGISTER);
    }

    return 0;
}