Error while mounting read-write

Hello,

I am trying to mount the entire filesystem with read-write rights (instead
of read-only).
While doing that, I get the following error:
*# mount -uf /*


*g_vfs_done():mmcsd0s2[WRITE(offset=20709376, length=4096)]error = 6UFS:
forcibly unmounting /dev/mmcsd0s2 from //dev/mmcsd0s2: Device not
configured*
*pid 25 (sh), jid 0, uid 0: exited on signal 4*

This happens on my fork but also on the 'freebsd/freebsd-src' main branch.
Even if the fstab says to mount as 'rw' the filesystem is mounted read-only.

Setup:

   - Buildworld, buildkernel, installworld, installkernel
   - copy the install* generated directory on the UFS partition on the SD
   card.
   - Copy the loader on the FAT32 partition (this one is for U-Boot)

Do you have any suggestion? What should be the best approach for this
problem?

Thanks,
Andrei Martin