Is it possible that the SD card slot does not work when using a Raspberry Pi Compute Module 4 with eMMC?

Hi,

I installed recalbox 8.02 on internal eMMC (16GB) memory. This works fine. Now I want to use an SD card (128GB) for roms. The SD card is not mounted automatically. How can I mount the SD card?

fdisk -l

Disk /dev/mmcblk0: 15 GB, 15634268160 bytes, 30535680 sectors
477120 cylinders, 4 heads, 16 sectors/track
Units: sectors of 1 * 512 = 512 bytes

Device Boot StartCHS EndCHS StartLBA EndLBA Sectors Size Id Type
/dev/mmcblk0p1 0,32,33 392,99,27 2048 6303743 6301696 3077M c Win95 FAT32 (LBA)
/dev/mmcblk0p2 392,131,60 1023,254,63 6305792 28436480 22130689 10.5G 7 HPFS/NTFS
/dev/mmcblk0p3 1023,254,63 1023,254,63 28438528 30535679 2097152 1024M 83 Linux

Only one Memory (internal eMMC) shows up. Why?

Thanks