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HCL:Zidoo X9S

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The Zidoo X9S is a TV box, shipping with Android pre-installed.

Technical data

Zidoo X9S (upside down) with UART cable attached
  • Realtek RTD1295 SoC
    • 4x ARM Cortex-A53 CPU
    • ARM Mali-T820 MP3 GPU
  • 2 GB RAM
  • 16 GB eMMC
  • Micro SD slot
  • 2x USB 2.0, 1x USB 3.0
  • SATA
  • 1x 1 Gb Ethernet
  • Realtek RTL8821AU Wifi module
  • 1x HDMI out, 1x HDMI in
  • SPDIF, AV out

UART access

The bottom plate can easily be unscrewed.

A male 2 mm connector is available below the board, between USB 3.0 and SATA connectors; the pins are also accessible from the top. Hints on which female connector to use welcome!

With a standard 0.1" TTL UART USB adapter, RX and TX can be plugged inside the connector and for space reasons GND elsewhere (e.g., via male-male cable to the USB connector in the corner).

Manual installation


The device first boots into a v2012.07 based AArch32 U-Boot. To get to a prompt, press space or ESC.

The default boot command, bootr, boots into a v2015.07 based AArch64 U-Boot with no timeout for pressing a key.

To get to a prompt in the second U-Boot, you can instead enter b2ndbc at the prompt of the first U-Boot.

tftp $kernel_loadaddr uImage
tftp $fdt_loadaddr rtd1295-zidoo-x9s.dtb
tftp $rootfs_loadaddr initrd.cpio.gz
fdt addr $fdt_loadaddr
fdt resize
env set bootcmd ""

Following that in aarch64 U-Boot:

setenv bootargs "earlycon initrd=$rootfs_loadaddr,0x$filesize"
bootm $kernel_loadaddr - $fdt_loadaddr

The uImage must use 0x00280000 as load address, or the Image needs to be built with patched TEXT_OFFSET (default: 0x80000) to boot successfully.

Mainline U-Boot does not yet contain support for this SoC or device.


Initial patch series sent (v1, v2, v3) and merged for 4.13.

The v4.13-rc1 kernel added initial support for this SoC and device, but needs additional DT tweaks to get serial working beyond earlycon.

UART cleanup: v1
Reset controller driver: v1
IRQ mux driver: v1 v2
Clock driver: v1
RTC driver: v1 v2 v3
Watchdog driver: v1

See also