Hi Jeff,

Thanks for your reply. After I wrote that post I found the exact same link (
https://eewiki.net/display/linuxonarm/BeagleBone+Black) and the "obligatory
patches" are basically what I was missing for building the MLO and
u-boot.img files for the EMMC.

Sorry if I wasn't clear - my task is to write the contents of the EMMC from
scratch using only an Ethernet connection. I'm doing that using BOOTP/DHCP
and TFTP. It's working now.


On Wed, 9 Aug 2017 at 02:20 Jeff Andich <jeff.and...@gmail.com> wrote:

> I'm a newbie, so take this with a grain of salt or as comic relief for the
> experts on this website.
> I don't completely understand what you're trying to do, but it sounds like
> the kernel some how contains/flashes MLO/u-boot.img???
> But maybe you can generate SD Card which contains everything you need
> (e.g. MLO, u-boot.img, kernel, fs, uEnv.txt) and then uncomment the
> appropriate line within uEnv.txt to convert that into a flasher image, and
> subsequently flash the eMMC...
> Instructions for where to get EVERYTHING and transfer it to SD card for
> the BBB can be found here:
> https://eewiki.net/display/linuxonarm/BeagleBone+Black
> Once you download the u-boot source and apply all of the the obligatory
> patches for BBB, you will have a buildable u-boot/SPL tree.
> In lieu of generating a complete SD card image, it MAY BE possible to dd
> just the MLO/u-boot.img to the eMMC on the BBB, but I think you can only do
> this from a running FS on the BBB.
> On Tuesday, August 8, 2017 at 6:55:12 AM UTC-5, wolfwo...@gmail.com wrote:
>> Hi,
>> I'm trying to automate the process of flashing a bootable emmc (NAND) on
>> my beagle bone black. I've pin strapped the board to boot using bootp/dhcp
>> - the kernel that gets loaded by the u-boot.img (that was pulled in via
>> dhcp+tftp) uses an initramfs as the basis of writing the MLO, (a different)
>> u-boot.img and root file system (containing zImage and uEnv.txt) to
>> emmc/NAND. This all works and when I restart the beagle bone black it boots
>> as I expect. Hooray for automated emmc flashing.
>> However my problem is that I can't seem to hand roll a version the the
>> MLO and u-boot.img that I flash to NAND. What I'm using right now are
>> copies I found of these two files in the debian images distributed here:
>> https://beagleboard.org/latest-images (These images tend to contain
>> filesystems with /opt/backup/uboot/MLO and /opt/back/uboot/u-boot.img files
>> existing). If I use these two boot loader files, and craft my
>> /boot/uEnv.txt just so (uuid needs to be specified), then I can boot a
>> couple of kernels/filesystems I have lying around successfully.
>> But I can't seem to reproduce these two files (MLO and u-boot.img) for my
>> NAND from source. I've tried these git repos:
>> git://git.denx.de/u-boot.git
>> git://git.ti.com/ti-u-boot/ti-u-boot.git
>> and even the u-boot source that that ships with the SDK:
>> ~/ti-processor-sdk-linux-am335x-evm-
>> For each of those I'm running
>> make CROSS_COMPILE=arm-linux-gnueabihf- O=am335x_evm am335x_evm_defconfig
>> && make CROSS_COMPILE=arm-linux-gnueabihf- O=am335x_evm
>> And I've even tried a different config:
>> make CROSS_COMPILE=arm-linux-gnueabihf- O=am335x_boneblack
>> am335x_boneblack_defconfig && make CROSS_COMPILE=arm-linux-gnueabihf-
>> O=am335x_boneblack
>> This compilation process creates the MLO and u-boot.img files, but I can
>> never seem to successfully boot anything if I use them regardless of which
>> config I use.
>> If it helps with clarity, I am trying out MLO and u-boot.img files by
>> booting from the SD card, copying over the new versions, and then running
>> dd if=MLO of=/dev/mmcblk1 conv=notrunc bs=128k count=1 seek=1
>> dd if=u-boot.img of=/dev/mmcblk1 conv=notrunc bs=384k count=2 seek=1
>> Note that I can always get back to the "bootable state" by writing the
>> backup boot loader files that come with debian distro instead: (the sd card
>> is running debian 8.7):
>> dd if=/opt/backup/uboot/MLO of=/dev/mmcblk1 conv=notrunc bs=128k count=1
>> seek=1
>> dd if=/opt/backup/uboot/u-boot.img of=/dev/mmcblk1 conv=notrunc bs=384k
>> count=2 seek=1
>> How can I build MLO and u-boot.img files in order to successfully boot a
>> kernel and file system of my choosing on the emmc/NAND? Is there a page
>> somewhere? Any help would be appreciated.

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