About the relocation table in DOS EXE header

Question

From the above we can see count of relocation table entries is 0 (there is no reloc item), but offset of first reloc item shows that the reloc item actually exists.

The definition of DOS EXE Header is here .

How to understand it?

Answer 1

This is normal. For modern formats like PE, the offset to the relocation table is always 0040H, even if there are zero relocation items.

Answer 2

You have to look at the EXE header size (shown as DOS_HdrSize in your screenshot). This is the number of paragraphs (16-byte blocks) that the whole header uses.

In your example it is 0x0004 so multiply it by 16 and you get the header length as 0x40 bytes. The relocation table starts at the relocation table offset and continues for DOS_ReloCnt entries until the end of the header.

In your case the relocation table offset is 0x40 and the end of the header is also 0x40 thus there is no room for the relocation table, which is just as well since DOS_ReloCnt says there are zero entries in it.

In this case it probably does not matter what value the relocation table offset is set to.