If you have inserted a SD card in your navigation device and there is no device created if you connect it via USB to your PC, make sure you have CONFIG_SCSI_MULTI_LUN enabled in your Linux kernel.

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[*] Probe all LUNs on each SCSI device
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OSM maps overview https://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/Download

• http://osm.thkukuk.de/
• https://wiki.openstreetmap.org/wiki/DE:OSMC_Reitkarte
• http://garmin.openstreetmap.nl/
• https://www.openmapchest.org/

https://www8.garmin.com/support/download_details.jsp?id=4523

• Get the latest file: https://download.garmin.com/software/Oregonx50_WebUpdater__660.gcd
• Attach your Garmin device to your computer and verify that it is in USB Mass storage mode
• Copy the downloaded file to ${MOUNT_POINT}/Garmin/gupdate.gcd
• Restart your Garmin device