Geckoloader

geckoloader - coded by dhewg, #wiidev efnet/blitzed

• latest version: v0.0.2b

about

geckoloader is a native wii application which helps you to load and execute wii homebrew binaries in the easiest and fastest way possible. It acts as a server which will receive binaries directly using a usbgecko adapter.

a client tool to transfer such files is included.

requirements

• a usbgecko adapter
• a gamecube pad
• a way to boot wii homebrew

architecture

geckoloader consists of 3 parts

• stub
• loader
• boot

the boot code contains the other two code parts, and it is the executable that you have to run. it will write the loader code to the onboard usbgecko flash and place the stub into memory

the boot code will then execute the stub

the stub's job is to read the loader code from flash and execute it

finally, the loader code will accept incoming .dol's sent using a client application from the pc side

the chosen architecture has the advantage that the tiny stub is the only component which has to stay intact in memory. while the usage of the usbgecko onboard flash might seem unnecessary at first, its purpose is the reloading feature. you will upload and run wii applications. these in return will allocate memory and write to it. if the loader code would stay somewhere in memory, any executed application might overwrite the loader code this way, but since it sits on the onboard usbgecko flash, no application can corrupt it.

features

• 100% native wii mode
• no medium ejecting, rewriting and inserting required whatsoever
• this is especially useful for wii coders (fast development cycle)
• the stub is placed at the memory location 0x80001800. this is PSO reload compatible, which means that any application can jump back there so that you can load another binary without reboot. the libogc exception handler also jumps to this address (when pressing START)
• the protocol used for uploading is compatible to the official geckotool (you can use your client of choice)
• as always, this is open source ;)

build

hint: a precompiled binary is included

to compile the included code, you will need devkitPPC and libogc r14 or higher

copy stub/stub.lds to $DEVKITPPC/powerpc-gekko/lib

check config.h for some tuneables

run make in the root dir

run make install to copy geckoupload (the client) to $DEVKITPPC/bin

usage

• use the Twilight hack in combination with the included geckoloader.elf to get this running
• the boot code will show up

• you have to write the loader code to the onboard usbgecko flash once, so press Z on your gamecube pad to do that
• just press A the next time you reboot the wii to skip the flash procedure

• after that you will see the loader code in action
• use a compatible client (like the included one geckoupload, or the official windows geckotool) to send a .dol
• the transfered binary should execute
• if you loaded a game/app which has an option to jump back to 0x80001800, you will be presented with the loader code again. from there, you can transfer another binary again (no reboot required)

hint: try to upload the included test.dol first. it just prints a string to screen and has an option to jump back to the loader

client usage

• set the environment variable USBGECKODEVICE to the tty device of the usbgecko adapter, eg:

export USBGECKODEVICE=/dev/ttyUSB0

• make sure that your console is ready to receive an executable
• pass the filename of the binary to geckoupload, for example:

geckoupload test.dol

you can use this client to transfer

• wii .dol's to the geckoloader described on this page
• gamecube .dol's to the official usbgecko boot dvd
• wii .elf's to the upcoming release of the twilight hack

notes

• please report back how it worked for you!
• only .dol files are supported
• you can not run gamecube binaries with this loader since we're working in wii mode here (that's a good thing)
• the included client will not compile using mingw, patches are welcome. update: i took the time to port it to win32. get on irc and ask me for a testing version if you're interested
• the uploaded data is not verified by neither the included client nor the receiving loader code. pay attention to what you are sending to avoid annoying reboots
• the default libogc base address for wii homebrew is at 0x80003f00. this gives a PSO compatible stub ~10k of memory. hence, the stub's main() functions were written in c so that it's easy to improve/fix
• the loader initially puts a received binary in MEM2 to avoid overlaps. it will be relocated from there. unfortunately the loader itself has a base address in MEM1. putting it in MEM2 is on my TODO list
• for the record: you can use the trucha signer to boot this app straight from dvd, but that is currently not supported nor endorsed. do not ask about it

thanks

• shagkur, for helping me getting the stub working and providing the linkerscript
• the devkitpro team
• team tweezers for making all of this possible
• all open source wii coders
• nuke for sharing code for his adapter

download

v0.0.2b

geckoloader-0.0.2b.tgz

v0.0.2

geckoloader-0.0.2.tgz

changelog

• v0.0.2b

• fixed a timing issue in the usbgecko flash code. since i couldn't reproduce this on my setup, thanks go out to bLAStY and NoNameNo for helping me hunting this one down
• the included client now works on os x thanks to bushing
• added an extra check for malformed .dol files (some doltool converted .elf's)
• included a tiny test application

• v0.0.2

• first public release