Thanks for your reply but I think i did not explain well:
I have a RPI3B+ with a 256GB Micro SD flashed with Batocera.
I connect the RPI3 to my local network and access to the "share partition" of batocera with Bios, rom etc...
I am unable to transfer more than 4GB to the SD Card although it has a lot of free space(around 130GB free).
How to extend the capacity of this share partition ?
I hope this is now clear.
Many thanks in advance for your help buddys.