User guide

Nios II IDE Help System

When you start a debug session, the Nios II IDE invokes the nios2-iss application. The

Nios II ISS supports all GDB debug facilities, such as the ability to set breakpoints, set

watchpoints, and view memory. Reading uninitialized memory or empty regions in the

memory map returns zero. Depending on the run/debug configuration, the ISS can generate a

warning or an error whenever a read occurs from uninitialized memory. Fetching an instruction

from these locations returns a zero instruction word (equivalent to call 0x0), which generally

causes your program to fail.

The IDE uses nios2-elf-gdb to communicate with nios2-iss over an automatically-selected

TCP/IP port. Invoking nios2-elf-gdb from the command-line also communicates over a

TCP/IP port.