FAT and Physical Disk Information

[siavoshkc]

Its not what I mean. I mean does it read MBR or obtains info from another source.

[Mario F.]

I'm assuming it reads the GPT. If the first logical block (LBA 0, the Protected MBR) does not contain a partition type of 0xEE (obtained from reading the 1-byte offset at 0x04), it knows it is reading a legacy device and uses the MBR instead.

[adeyblue]

Its not what I mean. I mean does it read MBR or obtains info from another source.

The source for the FAT filesystem driver comes with the WDK. Download it and be enlightened.

[siavoshkc]

Consider this:

The difference between IOCTL_DISK_GET_DRIVE_GEOMETRY_EX and the older IOCTL_DISK_GET_DRIVE_GEOMETRY request is that IOCTL_DISK_GET_DRIVE_GEOMETRY_EX can retrieve information from both Master Boot Record (MBR) and GUID Partition Table (GPT)-type partitioned media, whereas IOCTL_DISK_GET_DRIVE_GEOMETRY can only read MBR-style media.

It still does not clear if it reads from MBR(GUID) or somewhere else. If we persume it reads info from MBR, we should look for a more reliable source of disk info.