Please add some info about your setup, as detailed in https://retropie.org.uk/forum/topic/3/read-this-first. You also may want to edit your topic's title, it doesn't match the content you posted.

@dmmarti : Thank you for the hint, that was part of the solution that worked for me.

I did notice, that settings are not permanent and was in luck to find the entry „Update Input Remap File“ in the table „MANAGE REMAP FILES“.

@Floob : Thank you for the link to the documentation and mentioning necessary input_libretro_device_p3 settings.

In another libretro discussion I also found settings for _p1:

Input_libretro_device_p3 = „259“

Now I can also use my xbox controller.
For the „259“ setting, I couldn‘t find an explanation in the documentation. But now it works and I slowly start to understand what‘s necessary, to get other games running.

@ all : Many thanks for your instant support and helpful input!

@mlcampbe said in Confused mapping ipac buttons to retroarch for mame:

Is there a standard retroarch <--> mame key mapping that says retroarch "a" = mame "1SW1" and so forth?

1SW1 is an ipac designation, but afaik it effectively means "mame, player 1, button 1". with that in mind, you can see what retropad button = what mame button number via observing what is displayed in the core input remapping menu: https://retropie.org.uk/docs/RetroArch-Configuration/#core-input-remapping (where you can also adjust the mapping).

please fill out https://retropie.org.uk/forum/topic/3/read-this-first for more specific advice - not all mame cores have the input descriptors required for core input remapping.

You need to start a game first, the file doesn't exist until a game has been run. Make sure you toggle verbose logging when starting the game; after you exit the game you should have a log file in /dev/shm.

@mitu FANTASTIC !!!!
Everythings working with lr-fmsx!!! I focused to much on Lr-BlueMSX. For Lr-BlueMSX, It's only playable with keyboard . The joypad working only for Coleco. Not enough gamepad buttons are associated with basics keyboard fonctions. They should enable the "RetroPad Keyboard Map - Joypad - Awaiting description" option in Control menu in RetroArch for MSX.
Thank you
REGARDS

@Lazzarous_84 You can't make the ps3 driver work for an Xbox compatible controller. How is the controller detected ? As a PS3 controller or as an XBox controller ?

Update; the n64 emulator works perfect but issues with snes and nes

https://retropie.org.uk/forum/topic/4804/xiaomi-bluetooth-gamepad-after-4-0-6-update/8

try mine config as shown in link above

@RetroNoob can you see that message on top of every single page of this forum?
I'm pasting here for you:
Please do not post a support request without first reading and following the advice in https://retropie.org.uk/forum/topic/3/read-this-first

@mdg33

That's great to hear! Please keep us updated.

Looks like I can only assign channels when its connected to a PS3. I'm guessing I'll have to leave only one dongle in and then connect the second as and when I need a P2 pad.

@axis_d Most people will recommend a Logitech F710 or an 8bitdo model. I think those are a great choice.
I really dont like using an Xbox or PS3 type controller, not least due to the quirks of connection issues they can have.