struct hd_geometry

`struct hd_geometry` is a C struct used to represent the geometry of a hard disk. It includes the number of cylinders, heads, and sectors per track. This information is used by the operating system to access and manage the hard disk.

Here's an example definition of the `hd_geometry` struct:

struct hd_geometry {
    unsigned char heads;
    unsigned char sectors;
    unsigned short cylinders;
    unsigned long start;
};

In this example, `heads` represents the number of heads (read/write heads) on the hard disk, `sectors` represents the number of sectors per track, `cylinders` represents the number of cylinders on the hard disk, and `start` represents the starting sector of the partition.