uClinux in the GDB/ARMulator
----------------------------

This page can be found on the web at:

  http://www.uclinux.org/pub/uClinux/utilities/armulator/

The web copy contains real links to many of the packages described herein.


Here are some patches to GDB to allow the existing gdb ARM emulator to run
uClinux targets. It can run both little-endian and big-endian code, as well
as apcs-32/26 code and Thumb. I have tested little/big endian kernels but
haven't played with thumb at this point.

The patch is heavily based on an ARM7100 patch that Ben Williamson produced
back around 1999 for gdb-4.18. The changes include Atmel AT91 emulation for
timers/system registers and serial ports, removal of Bens LCD support and
porting to gdb-5.0.


1. Getting GDB/ARMulator

   Here are the files you need to use to put together the GDB/ARMulator.

   gdb-5.0.tar.bz2
	The orginal gdb-5.0 archive.

   gdb-5.0-uclinux-armulator-20021127.patch.gz
	Patches against gdb-5.0 based heavily on the ARMulator changes from
	Ben Williamson <benw@pobox.com> with changes to behave like an Atmel
	AT91 device.


2. Building GDB/ARMulator

	bunzip2 < gdb-5.0.tar.bz2 | tar xvf -
	gunzip < gdb-5.0-uclinux-armulator-20021127.patch.gz | patch -p0
	cd gdb-5.0
	./configure --target=arm-elf
	make
	su root -c "make install"


3. Compiling uClinux

   During the configuration stepo choose GDB/ARMulator as the target. You
   can select either the linux-2.0.x or linux-2.4.x kernels, and you can
   choose either uC-libc or uClibc as the libaray.


4. Running the Binaries

   The ARMulator expects the romfs to be in a file called "boot.rom".
   So link the romfs.img to boot.rom with:

	ln -s images/romfs.img boot.rom

   Then to run uCLinux do:

	arm-elf-gdb linux-2.X.X/linux

   Then within gdb do:

	...
	gdb> target sim
	...
	gdb> load
	...
	gdb> run

   To save some typing you can create a .gdbinit file that conatins:

	target sim
	load

   Then you just need to use "run" to start the kernel each time.

5. Using the Debugger

  Just type ^C to drop into gdb. You have full source debugging of the kernel
  (and apps if you load their symbols appropriately). You can step and
  continue just like a normal debugger.


6. Messing with the Emulator

   If you want to see how much of a hack this really is, the main files to
   look at are:

	gdb-5.0/sim/arm/armmem.c
	gdb-5.0/sim/arm/armio.c

   These still include the old 7100 code commented out and the Atmel
   emulation that is truly hacked in on top. You can add more memory and
   change the size of the rom in armmem.c. You can fix most bugs in the
   emulation in armio.c.


7. Thanks to

   Patrick Doyle for the time.h patch to fixcompiling on RedHat 7.2/7.3
   Fernando José Cardozo de Sá for his Native 32 port (and binaries).
   Daniel Versick's big-endian patches for uaccess
	(taken from http://mac.os.nctu.edu.tw/distfiles/4530.patch).


Copyright (C) 2002,
David McCullough <davidm@snapgear.com>