FILECORE_BOOT_SECTOR
if (pread(f, bb, sizeof(bb), (off_t)FILECORE_BOOT_SECTOR * DEV_BSIZE) != sizeof(bb))
FILECORE_BOOT_SECTOR, DEV_BSIZE, buf, &rsize);
bp->b_blkno = FILECORE_BOOT_SECTOR;
bp->b_blkno = FILECORE_BOOT_SECTOR;
if (lseek(fd, (off_t)FILECORE_BOOT_SECTOR * DEV_BSIZE, SEEK_SET) < 0