goshil
commented
6 years ago +1 Yeah, really, 4.x has different structure, some files are patchable, some - not. If somebody will guide in applying this patchset to 4.x, it will be great!
Closed aw1cks closed 2 years ago
goshil
commented
6 years ago +1 Yeah, really, 4.x has different structure, some files are patchable, some - not. If somebody will guide in applying this patchset to 4.x, it will be great!
jhoola86
commented
6 years ago Is source available for 4.x kernel versions ?
I couldn't find them in git repo
conrad-heimbold
commented
6 years ago @jhoola86 : no, unfortunately not (yet).
aw1cks
commented
6 years ago any update on this? is it planned at all?
conrad-heimbold
commented
6 years ago If anybody wants to create a patch for kernel 4.4 by themself, a quote from issue #12 on how @pelya invented the code:
First, there is a kernel patch - this is dark magic, without which nothing will work. This patch adds two new devices to your Android system, /dev/hidg0 for keyboard, and /dev/hidg1 for mouse. If you want to add HID joystick for example, you need to modify hid_function_bind_config() and hid_function_init(), and another struct ghid_device_android_joystick, with proper USB descriptor. The best way to get USB descriptor is to buy USB analyzer, and copy data from existing USB joystick. You can also read USB specification: http://en.wikipedia.org/wiki/USB_human_interface_device_class
Then you need Android application, which will write data to these devices. It doesn't matter if it's written in C or Java, as long as it writes valid data to these files. Keyboard/mouse protocol description is here: https://github.com/pelya/android-keyboard-gadget#how-it-works My Android app is written in C++ and uses SDL library. gfx.cpp contains low-level graphics functions, gui.cpp is a GUI widgets implementation, flash-kernel.cpp is for flashing kernel on Nexus 7, input.cpp is for opening device files and writing data to them, main.cpp is, well, main(), touchpad.cpp is the touchpad implementation, and scancodes.cpp contains keyboard scancode table.
I do not know all details myself, because the kernel is huge, I only know how my code works.
First, I've read this documemt, it contains half-baked example of what I needed:
https://github.com/torvalds/linux/blob/master/Documentation/usb/gadget_hid.txt
Then I've scanbed through Android USB gadget implementation, where functions are added and removed dynamically:
HID gadget already has it's own driver, I needed only to provide USB HID descriptor:
Then I fixed compilation errors, run, debugged crashes, usual stuff.
how can I go about patching a 4.4.x branch kernel?