g_multi and sdcard = unformatted drive on Windows

[marc21...@googlemail.com]

Hi,
i have a new BBBW and try to "export" the sdcard as USB-Massstorage.
So i have to unload g_multi with modprobe -r g_multi, and mount it again with

modprobe g_multi file=/dev/mmcblk0p1 ro=0 cdrom=0 stall=0 removable=1

(the same behavior with g_mass_storage)

I formatted the SDCard to Fat32, but on a WindowsHost i see only a unformatted drive appear, so i decided to format the drive with Windows to fat32, that work fine, i can now write/read data to the SDCard, even if i unload g_multi and mount it again, the data are still there.

But the Problem is, if i unload g_multi and mount the SDcard under linux, i see no Files on it... (there should be some Textfiles)

Now i have checked the free Space on it, and there I see, it isn't empty 

/dev/mmcblk0p1  15541920  2712  15539208   1% /media/sdcard

root@beaglebone:~# ls -la /media/sdcard/

total 12

drwxr-xr-x 2 root root 8192 Apr 12 16:30 .

drwxr-xr-x 3 root root 4096 Nov  6 15:55 ..

Now i left with no Idea, why this happens, and i have following Questions:

1. Why do Windows show the drive unformatted first (Fat32 should be no Problem)?

2. Why can't linux read the data on the sdcard?

Or did i just missunderstand how g_multi "export" a Filesystem.