main/postmarketos-mkinitfs: Add option to place DTB in Android boot image second area

Mainline U-Boot looks for the device tree blob in the "second" area of the Android boot image (see https://patchwork.ozlabs.org/patch/1025211/).
Add an option deviceinfo_bootimg_dtb_second to place the device DTB there. (The option sounds pretty bad, I'm open for alternative suggestions...)

I'm working on a mainline U-Boot port for NovaThor U8500 devices. It needs this option to boot mainline.

Related pmbootstrap MR: https://gitlab.com/postmarketOS/pmbootstrap/merge_requests/1828

mentioned in merge request pmbootstrap!1828 (merged)

By Minecrell on 2019-10-25T15:12:09

changed the description

By Minecrell on 2019-10-25T15:33:49

added type::feature + 1 deleted label

Why does your u-boot boot an android formatted boot.img at all? why not one of the more native u-boot formats?

By Martijn Braam on 2019-10-25T23:18:47

Patch looks good to me (this one and the pmbootstrap one are both excellent!), but waiting with merge until @MartijnBraam's question is answered.

By Oliver Smith on 2019-10-25T23:21:00

@MartijnBraam Of course, my U-Boot version is also capable of booting the other U-Boot image formats. The Android boot image format is just one of the U-Boot image formats supported in mainline. Which one to use is then a matter of preference.

I use U-Boot as a way to have a Fastboot interface on the Samsung-based NovaThor U8500 devices. On these devices, U-Boot does not replace the Samsung bootloader - U-Boot is packed into an Android boot image and then loaded by the Samsung bootloader.

Some of the reasons for using Android boot images in this case:

• There is no way to get rid of the Android partition layout. With the U-Boot "distro defaults" you usually need an extra boot partition.
• My version of U-Boot can boot both (downstream) Android and mainline, so it must be able to load Android boot images.
• At the moment, pmbootstrap + Fastboot (i.e. pmbootstrap flasher boot) is the most most convenient way to develop kernels I'm aware of. However, Fastboot requires Android boot images.

By Minecrell on 2019-10-26T09:00:25

added 9 commits

• b89ef633...93d7dc41 - 8 commits from branch postmarketOS:master
• 74815e33 - main/postmarketos-mkinitfs: add option to place DTB in Android boot image second area (!700 (merged))

Compare with previous version

By Oliver Smith on 2019-10-30T18:15:51

Thanks for explaining your use case, @Minecrell. Makes sense to me, let's ship it.

By Oliver Smith on 2019-10-30T18:17:31

approved this merge request

By Oliver Smith on 2019-10-30T18:17:55

resolved all threads

By Oliver Smith on 2019-10-30T18:18:23

merged

By Oliver Smith on 2019-10-30T18:18:34

mentioned in commit wiki@28674391

By postmarketOS Wiki bot on 2019-10-30T18:43:12

mentioned in commit 74815e33

By Minecrell on 2019-11-07T18:16:49