Rockchip Boot Stuck at "Waiting for root device": Fix

Symptoms

Boot stops at "Waiting for root device ..."
Happens after a kernel or DTB change, or when moving from SD to eMMC/NVMe

Common causes

Storage driver built as a module without an initramfs (MMC, SDHCI, NVMe, PCIe PHY)
mmcblk numbering changed (SD vs eMMC order differs between kernels)
root=/dev/... points at the wrong partition
Storage controller disabled in the DTB

How to fix it

Use UUIDs, not device names

blkid   # on a working system
# extlinux.conf:
append root=UUID=<rootfs-uuid> rootwait rw console=ttyS2,1500000

Build storage drivers in

# eMMC on newer SoCs + SD + NVMe
CONFIG_MMC_DW_ROCKCHIP=y
CONFIG_MMC_SDHCI_OF_DWCMSHC=y
CONFIG_BLK_DEV_NVME=y
CONFIG_PCIE_ROCKCHIP_DW_HOST=y

Confirm the controller is enabled
Check the sdhci/sdmmc/pcie nodes have status = "okay" in the DTB the bootloader actually loads.

Go deeper

FAQ

What does "Waiting for root device /dev/mmcblk0p2..." mean?

The kernel booted but cannot find the root filesystem named in root=, because the storage driver is missing or the device name/UUID is wrong.

What causes "Waiting for root device /dev/mmcblk0p2..."?

Storage driver built as a module without an initramfs (MMC, SDHCI, NVMe, PCIe PHY); mmcblk numbering changed (SD vs eMMC order differs between kernels); root=/dev/... points at the wrong partition; Storage controller disabled in the DTB.

How do I fix "Waiting for root device /dev/mmcblk0p2..."?

1. Use UUIDs, not device names 2. Build storage drivers in 3. Confirm the controller is enabled: Check the sdhci/sdmmc/pcie nodes have status = "okay" in the DTB the bootloader actually loads.