Debugging
When developing for the Playstation Portable (PSP), you may run into crashes or code that does not quite work like expected. Figuring out what is going in is called debugging. This page will cover how to do that.
PSPLINK
PSPLINK is THE tool to use for debugging on the PSP. It is an application which allows you to run and debug programs for the PSP from your PC through USB.
Setting up PSPLINK
Each system involved in the use of PSPLINK requires a bit of setup for it to work. This includes both PSP and PC. Below are instructions for both.
PSP
Download the latest version of PSPLINK for the PSP here and extract it in ms0:/PSP/GAME
on the PSP memory card.
PC
Depending on the operating system used the setup on PC is different. Follow the on below which is relevant to your system.
Windows
On Windows a driver needs to be installed before PSPLINK can be used. To do this take the following steps:
- Make sure the programs
usbhostfs_pc
andpspsh
are available in cmd. Otherwise download them here. - Start PSPLINK on the Playstation Portable and connect it to the computer through USB.
- Download Zadig and start it. It will ask if you want to run it as administrator, click yes.
- In Zadig, click on
options
->List All Devices
. - Select the entry
"PSP" type B
from the dropdown list. - Left of driver, select the
libusb-win32
driver. Then click install. - Wait for the installation to finish, then disconnect the USB cable from the PSP.
Now PSPLINK can be used with Windows. See below how to do that.
Linux
With Linux PSPLINK will work without making any changes, but it will require using sudo for the usbhostfs_pc
command. To make it work without sudo, a udev rule can be added.
To make using PSPLINK without sudo create file called /etc/udev/rules.d/50-psplink.rules
(for example with sudo nano /etc/udev/rules.d/50-psplink.rules
) and add the following content:
SUBSYSTEM=="usb", ATTR{idVendor}=="054c", ATTR{idProduct}=="01c9", SYMLINK+="psp", MODE="0666"
Save this, in Nano this can be done with Ctrl+O and pressing enter. The run the following command:
sudo udevadm control --reload
Now PSPLINK can be used without sudo. See below how to do that.
Using PSPLINK
To be able to use PSPLINK with Playstation Portable homebrew, the homebrew will need to be build into an unencrypted .prx
file. This can be done by running CMake like psp-cmake -DBUILD_PRX=1 .
or if you’re using a Makefile by adding BUILD_PRX=1
to it. Then build the homebrew.
In the build directory, open a terminal and run the following program:
usbhostfs_pc
Keep this running!
Then open another terminal window and run the following there:
pspsh
Now we can simply start our homebrew on the PSP by running the following command in the pspsh window:
./myhomebrew.prx
Replace myhomebrew with the name of the .prx
file which was generated.
When you’re done with the current build, just run reset
, rebuild the homebrew and try again.
Options available can be found when using the help
command, but here are some notable ones:
scrshot screenshotname.bmp
for taking a screenshot.exit
for closing PSPLINK on the PSP.poweroff
for shutting down the PSP.
Getting Basic Crash Information
When a crash happens a crash log will be shown with a hint of what might have happened at the top and some additional info. If you wish to figure out where the crash happened, only the address is needed.
To figure out where the crash happened, open another terminal in the build directory and use the address shown by PSPLINK in the following command:
psp-addr2line -e myhomebrew address
Replace address
with the actual adress and replace myhomebrew with the name of the elf file. This is NOT the .prx
file and either has no extension or .elf
depending on the build system used.
If no result is returned, make sure to build with the -g
or -g3
option and without the -O
option to make sure psp-addr2line
knowns the function names and locations.
The information received from psp-addr2line
will be limited and not always useful, for more information you’ll have to use a debugger as described below.
Using a Debugger
When using psp-addr2line
is not enough to figure out what is going on, the best way to debug will be by using an actual debugger called GDB. PSPLINK allows you to enable access to psp-gdb
which comes bundles with the PSPDEV toolchain.
Preparation
Prepare a separate terminal for usbhostfs_pc
, pspsh
and psp-gdb
. Open all of them in the directory in which your compiled .prx
and the elf
(PSP binary) files are located.
1. usbhostfs_pc
Run usbhostfs_pc
on your terminal dedicated for usbhostfs_pc
and you will see the waiting for device...
status.
Now start the PSPLINK app on your PSP and connect the USB cable. You should see the connected to device
status in the terminal, which means success.
Do not close this terminal after that.
2. pspsh
Run pspsh
on your terminal dedicated for pspsh
and you will see the host0:/>
. Now run debug file.prx
, and it will display something like this:
PSPLink USB GDBServer (c) 2k7 TyRaNiD
host0:/> Loaded host0:/<file.prx> - UID 0x0408A763, Entry 0x088040AC
You need to replace
file.prx
with the file you need to debug. This is a.prx
file.
It means the debugger is succesfully loaded. You can type reset
if there’s something wrong with your GDBServer.
3. psp-gdb
In a new terminal run psp-gdb file -q
and you will see something like this:
You need to replace
file
with the elf file of the program you’re trying to debug. It has the same name as the file loaded in pspsh, but without the.prx
ending.
Check if your binary has enabled the debug symbols required for debugging by using
objdump --syms
command and should produce an output but if it saysno symbols
then it is disabled(You can enable it by adding-g
option to gcc).
Reading symbols from <file>...
(gdb)
<file>
is the name of the binary you are debugging.
then type the target remote :10001
to connect to your GDBServer and you will see the gdb output something like this:
Remote debugging using :10001
_start (args=0, argp=0x0) at crt0_prx.c:103
103 if (&sce_newlib_nocreate_thread_in_start != NULL) {
(gdb)
This will display the _start
routine, it means you succesfully connected and ready to the debug your app!
Here are a few useful commands for getting around in psp-gdb:
b
orbreak
- for setting breakpointsc
orcontinue
- for resuming program execution until the next breakpoint or program completions
orstep
- for executing the current line and, if it contains a function call, step into that functionn
ornext
- for executing the current line, but if it contains a function call, step over it without diving into the functionf
orfinish
- for executing the remaining lines of the current function and return to the callerbt
orbacktrace
- for getting stacktracep $var
orprint $var
- for displaying the value of specific variablei r
orinfo registers
- for displaying the contents of CPU registersd
ordelete
- for deleting all breakpointsq
orquit
- for exiting from psp-gdb
You can type help
for more information about the psp-gdb commands.
Done
Now you know how to debug your code. Make sure to check out the Tips and Tricks section to get most out of your PSP development experience.