In a MMCCAM enabled kernel we make some "mmcsd" aliases so we are backward compatible with non-MMCCAM kernel. This seems to fail for eMMC. Logs : (pass0:sdhci_slot0:0:0:0): XPT info: CLK 399193, ... (sdda0:sdhci_slot0:0:0:0): Periph created (sdda0:sdhci_slot0:0:0:0): Capacity: 62537072640, sectors: 122142720 (sdda0:sdhci_slot0:0:0:0): Set SD freq to 52 MHz (min out of host f=198 MHz and card f=52 MHz) sdhci_fdt0-slot0: Divider 2 for freq 49500000 (base 198000000) (sdda0:sdhci_slot0:0:0:0): Set bus width to 8-bit (min of host 8-bit and card 8-bit) (sdda0:sdhci_slot0:0:0:0): Partition type 'default', size 62537072640 (sdda0:sdhci_slot0:0:0:0): Partition type 'boot0', size 4194304 GEOM: new disk sdda0 (sdda0:sdhci_slot0:0:0:0): Partition type 'boot1', size 4194304 (sdda0:sdhci_slot0:0:0:0): Partition type 'RPMB', size 4194304 (sdda0:sdhci_slot0:0:0:0): Don't know what to do with RPMB partitions yet sdda0 at sdhci_slot0 bus 0 scbus0 target 0 lun 0 sdda0: Relative addr: 00000002 Card features: <MMC Memory High-Capacity> Card memory OCR: 40ff8080 sdda0: Serial Number 1A61E8CB (sdda0:sdhci_slot0:0:0:0): XPT info: CLK 49500000, ... sdda0: MMCHC DF4064 0.1 SN 1A61E8CB MFG 08/2001 by 69 0x0000 GEOM: new disk sdda0boot0 GEOM: new disk sdda0boot1 (sdda0:sdhci_slot0:0:0:0): Partition 0 -> 1 g_dev_taste: make_dev_alias_p() failed (name=mmcsd0, error=17) (sdda0:sdhci_slot0:0:0:0): Partition 1 -> 2 (sdda0:sdhci_slot0:0:0:0): Partition 2 -> 0 This might be related to boot partitions but needs to be checked more.