The Wii U currently has homebrew execution in both the PowerPC kernel and the ARM9 kernel (nicknamed IOSU by the community). The most common way to execute code on the Wii U for 5.5.1 and below is through vulnerabilities in the Wii U's built in web browser. There are many different userland and PowerPC kernel exploits in the Wii U internet browser. The earliest userland exploits used C code (on versions 2.0.0-5.3.2) and libstagefright bugs (on versions 5.4.0-5.5.1) to load custom code in the browser, with memory and permission limitations. The first kernel exploit found in the browser, called osdriver, only works on system versions 5.3.2 and lower, but this is no longer used as the 5.5.1 and lower exploit is more reliable. Currently, two different browser kernel exploits are used in the community. The first exploit found works on 5.5.1 and below and is very reliable. The other kernel exploit works on 5.5.2 and below, but due to its unreliability, it is only used on 5.5.2 to install Haxchi. Haxchi exploits the fact that DS virtual console game data is only checked when the game is installed. When installed to a DS virtual console game, Haxchi launches homebrew directly (such as the Wii U Homebrew Launcher) using an exploit installed in the game's file location. There is also an additional, optional, part of Haxchi called "Coldboot Haxchi" or CBHC. CBHC allows custom firmware to be enabled automatically each time the system is turned on, whereas other exploits have to be ran every time manually. However, CBHC has an increased risk of rendering the system inoperable as deleting the virtual console game (among other things) will break the console.