3.7. Using Flash Memory
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## 3.7. Using Flash Memory

Sourcery G++ Lite supports development and debugging of applications loaded into flash memory on MIPS ELF targets. There are three steps involved:

1. You must use an appropriate linker script that identifies the ROM memory region on your target board, and locates the program text within that region. Refer to Chapter 5, “CS3™: The CodeSourcery Common Startup Code Sequence” for information about the boards supported by Sourcery G++.

2. Next, load your program into the flash memory on your target board. You must use third-party tools to program the flash memory.

3. Finally, when debugging a program in flash memory, GDB must be told about the ROM region so that it knows where it must use hardware breakpoints to control program execution. If you are using the Sourcery G++ Debug Sprite to debug your program, the Sprite does this automatically, using the memory map provided in the board configuration file. Otherwise, you must provide this information explicitly.

   When using GDB from the command line, you can mark the flash memory as read-only by using the command:

       (gdb) mem start end ro

   where `start` and `end` define the address range of the read-only memory region.

Although GDB automatically attempts to use hardware breakpoints on code locations in the read-only memory region, on many targets the number of available hardware breakpoints is very small. Furthermore, GDB also uses hardware breakpoints internally to implement commands such as step, next, and finish. Thus the number of breakpoints you can explicitly set in ROM may be fewer than the number supported by the target system.

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