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Flash an Image to eMMC

Use this page to write a complete image to a board's eMMC, for example on a production line, on a board you designed, or with an image that is not a published release. You run every step yourself, so it works with any image file you have.

To update a DevKit to a published SiMa.ai release, use Firmware Update instead. To replace only the kernel, device trees, or U-Boot on a board that already boots, see Install the Artifacts.

Before You Start​

  • A board that reaches the U-Boot prompt.

  • A serial connection to the board's U-Boot/Linux UART at 115200 baud with hardware flow control disabled. See Configure Serial Connection.

  • The image to flash:

    ImageFiles
    eLxrelxr-palette-modalix-<version>-arm64.img
    Yoctosimaai-image-minimal-modalix.rootfs.wic.gz and simaai-image-minimal-modalix.rootfs.wic.bmap

    The Yocto file names are the ones that Build a Complete Image with Yocto produces. Another image recipe gives other names.

  • Either a host with Ethernet and a TFTP server, or an SD card.

How the Board Chooses a Boot Source​

A board can't overwrite the eMMC while it is running from it, so it first boots from the network or an SD card. U-Boot tries the sources in boot_targets in order:

TargetBoots from
mmc1SD card
mmc0eMMC
dhcpTFTP server found through DHCP
netTFTP server at a static IP address

The default order is mmc1 mmc0 dhcp net. To change it, interrupt autoboot in the serial console, then set and save the order:

sima$ env set boot_targets mmc1 mmc0 net dhcp; saveenv
Saving Environment to FAT... OK
sima$ printenv boot_targets
boot_targets=mmc1 mmc0 net dhcp
sima$ boot

Step 1. Boot From the Network or an SD Card​

Booting from an SD card is preferred on a test station, because it leaves the Ethernet ports free for network stress tests.

Boot from the network

This uses your own TFTP server, so you choose what it serves. Net Boot Recovery does the same with sima-cli, which downloads and serves a published release for you.

  1. Copy the boot files to the TFTP server's root directory:

    • netboot.scr.uimg
    • Image
    • the device tree blobs (*.dtb)
    • the root filesystem archive: elxr-palette-modalix-arm64.cpio.gz for eLxr, or simaai-image-palette-modalix.cpio.gz for Yocto

  2. Connect the host to the board's first Ethernet port (eth0). The board uses 192.168.1.20, so give the host an address on 192.168.1.0/24:

    sima-user@sima-user-machine:~$ sudo ifconfig <interface_name> 192.168.1.10 up

  3. Power on the board, interrupt autoboot, and make net the first boot source:

    sima$ env set boot_targets net mmc0 mmc1 dhcp; saveenv
    sima$ boot

  4. After Linux boots, confirm the build and that the root filesystem is in RAM (root=/dev/ram0):

    root@modalix:~# cat /etc/buildinfo
    root@modalix:~# cat /proc/cmdline
Boot from an SD card

  1. Write the image to the SD card. You can write it from the host with Create Boot Image, or from a board you booted from the network with the SD card inserted (/dev/mmcblk1):

    For eLxr:

    root@modalix:~# dd if=/tmp/elxr-palette-modalix-<version>-arm64.img of=/dev/mmcblk1 bs=4M status=progress conv=fsync

    For Yocto, copy both the .wic.gz and .wic.bmap files, then:

    root@modalix:~# bmaptool copy /tmp/simaai-image-minimal-modalix.rootfs.wic.gz /dev/mmcblk1

    Then repair the partition table. The image is smaller than the card, so the backup GPT header is not at the end of the device until parted moves it:

    root@modalix:~# printf "fix\n" | parted ---pretend-input-tty /dev/mmcblk1 print

  2. Reboot, interrupt autoboot, and make sure mmc1 comes first. It does by default:

    sima$ env set boot_targets mmc1 mmc0 dhcp net; saveenv
    sima$ boot

  3. After Linux boots, check /etc/buildinfo, and check /proc/cmdline for root=/dev/mmcblk1p*.

Step 2. Write the Image to eMMC​

Run these steps on the board, as root, while it is booted from the network or the SD card.

  1. Copy the image from the host to /tmp on the board.

    For eLxr:

    sima-user@sima-user-machine:~$ scp elxr-palette-modalix-<version>-arm64.img root@192.168.1.20:/tmp/

    For Yocto, copy both the .wic.gz and .wic.bmap files:

    sima-user@sima-user-machine:~$ scp simaai-image-minimal-modalix.rootfs.wic.* root@192.168.1.20:/tmp/

  2. Write the image to the eMMC (/dev/mmcblk0).

    For eLxr:

    root@modalix:~# dd if=/tmp/elxr-palette-modalix-<version>-arm64.img of=/dev/mmcblk0 bs=4M status=progress conv=fsync

    For Yocto:

    root@modalix:~# bmaptool copy /tmp/simaai-image-minimal-modalix.rootfs.wic.gz /dev/mmcblk0

  3. Repair the partition table:

    root@modalix:~# printf "fix\n" | parted ---pretend-input-tty /dev/mmcblk0 print

Step 3. Boot From eMMC​

  1. If you booted from the network, restore the default boot order:

    sima$ env set boot_targets mmc1 mmc0 dhcp net; saveenv

    If you booted from an SD card, remove it.

  2. Reboot or power-cycle the board and confirm it boots from eMMC.

Next Steps​