hi Robert,
On Fri, May 19, 2017 at 5:20 PM, Robert P. J. Day rpjday@crashcourse.ca wrote:
before i get to installing and/or booting the linux image i build with openembedded, i'd like to boot simply to the appropriate u-boot binary for this target board.
first, i've already bitbaked an absolutely stock "core-image-minimal" image for this board without issue using the meta-qcom layer at
git://git.yoctoproject.org/meta-qcom
although nicolas tells me that that layer is more generally maintained on github at:
they really are the same layer. the one on YP git is a mirror. So you can use one or the other, without any constraint. I just mentioned github in my other email so that you know where to send patches if needed.
but that's easy enough to change. haven't booted into that image yet, just wanted to verify that the build worked with no problem and produced all the artifacts i expect from an OE build. worked flawlessly.
to add u-boot to the build process, i went back and added the following lines to my local.conf:
EXTRA_IMAGEDEPENDS += "u-boot" UBOOT_MACHINE = "dragonboard410c_config"
again, build appeared to work perfectly, and generated the new artifact:
u-boot-dragonboard-410c-2017.01-r0.bin
nice.. i never tried building uboot from OE for DB410c!
so, again, looks good. at this point, it appears that the recipe for booting to u-boot is in the readme.txt file in the appropriate directory in the u-boot source:
http://git.denx.de/?p=u-boot.git%3Ba=blob%3Bf=board/qualcomm/dragonboard410c...
can anyone verify that that is still the correct set of instructions?
yes, the instructions are still correct. basically what we are doing is a 'chained' bootloader. u-boot is loaded by the LK bootloader, and it is not a full replacement for the QCOM bootloader. So we create a 'boot' image that can be loaded and started by LK.
You have mkbootimg and dtbTool recipes in meta-qcom, i would happily take u-boot .bbappend patch that implement the instructions from the readme and build a 'working' u-boot image file.
and as i read it, to get to "fastboot" mode, i don't need the FTDI connection, just USB OTG should do it, is that correct?
yes, correct, you don't *need* serial console.. however if anything goes wrong you will really need serial console.. My recommendation is to plan for it.. In fact I recommend the 96boards serial adaptor: http://www.96boards.org/product/uarts/.
is there a way to install the u-boot binary on the SD card and boot directly from there?
yes, it's possible to boot from SD, instructions to create a bootable SD card (on DB410c) are available here:
https://github.com/96boards/documentation/blob/master/ConsumerEdition/Dragon...
of course I would happily take patches in meta-qcom to facilitate the creation of bootable SD cards.. ;)
rday
--
======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca
Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================
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