3.6.1.12 Reserve Option

The -mreserve=ranges option allows you to reserve memory normally used by the program. This option has the general form:
-mreserve=space@start:end

where space can be either of ram or rom, denoting the data and program memory spaces, respectively; and start and end are addresses, denoting the range to be excluded. For example, -mreserve=ram@0x100:0x101 will reserve two bytes starting at address 100h from the data memory.