I believe that I had the same concern. After rebooting an upgraded system (uptime of 6+ months), my SD card didn't appear in /dev/sd* .
lsusb showed the card reader: Bus 003 Device 004: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller My dmesg output looked like: [ 1090.387710] mmc0: card 59b4 removed [ 1097.802651] mmc0: new ultra high speed SDR50 SDXC card at address 59b4 [ 1097.802874] mmcblk0: mmc0:59b4 SD64G 59.6 GiB [ 1097.804711] mmcblk0: p1 After an hour or more of poking around the web, it appears that the device is now exposed in /dev/mmc* # ls /dev/mmc* /dev/mmcblk0 /dev/mmcblk0p1 With that new knowledge, I again attempted to mount... # mount /dev/mmcblk0p1 /media/usbSD/ # Huzzah. Works great.
