Cross-development environment

f78 Cross-development environment

Cross-development environment
Using GNUPro Toolkit in one of the cross-development configurations usually requires some attention to setting up the target environment.

A cross-development configuration can develop software for a different target machine than the development tools themselves (which run on the host)--for example, a SPARCstation can generate and debug code for a Motorola Power PC-based board.
For our tools to work with a target environment (except for real-time operating systems, which provide full operating system support), set up the tools by using the following documentation.

To set up the C run-time environment, see The C run-time environment (crt0).
To create stubs, or minimal versions of operating system subroutines for the C subroutine library, see System Calls in GNUPro C Library in GNUPro Libraries.
To understand the connection to the debugger, see Remote debugging in Debugging with GDB in GNUPro Debugging Tools.

The C run-time environment (`crt0`)

To link and run C or C++ programs, you need to define a small module (usually written in assembler as 'crt0.s') that makes sure the hardware is initialized for C conventions before calling main.

There are some examples of crt0.s code (along with examples of system call stub code) available in the source code for GNUPro Toolkit. Look in the following path.

installdir /gnupro-98r1/src/newlib/libc/sys

installdir refers to your installation directory, by default '/usr/cygnus'.

For example, look in '.../sys/h8300hms' for Hitachi H8/300 bare boards, or in '.../sys/sparclite' for the Fujitsu SPARClite board.

More example ffb s are in the following directory.

installdir /gnupro-98r1/src/newlib/stub

To write your own crt0.s module, you need the following information about your target.

A memory map. What memory is available, and where?
Which way does the stack grow?
What output format do you use?

At a minimum, your crt0.s module must do the following processes.

Define the symbol, start (_start in assembler code).

Set up the stack pointer, sp.

bss

Initialize all memory in the uninitialized-data (bss) section to zero.

Command Language

Using LD

GNUPro Utilities

bss_start

bss_end

for

crt0.s

Call main.

A more complete crt0.s module might also do the following processes.

Define an _exit subroutine.

__exit

start

If your target has no monitor to mediate communications with the debugger, you must set up the hardware exception handler in the crt0.s module.

The gdb remote serial protocol

Debugging with GDB

GNUPro Debugging Tools

gdb

Perform other hardware-dependent initialization.

mmu

Define low-level input and output subroutines.

crt0.s

System Calls

GNUPro C Library

GNUPro Libraries

The C run-time environment (crt0)

The C run-time environment (`crt0`)