There are three way to enter fastboot mode Fastboot command. So we can use this protocol to flash partition on your device. Google have submit the fastboot code to mainline U-boot.
Awesome Open Source is not affiliated with the legal entity who owns the. So every fastboot command have to use '-i' parameter to specify vid to fastboot.FastBoot to the Future Notes from my Ember PDX Talk. This VID is not in Googles original fastboot code.
Fastboot Source Code Driver To Version
So qcom could provide a standard device tree for their SOC - and then Fairphone could put all their stuff in the overlays - enabling or disabling features as needed or changing some wiring. It’s thinkable that - even though we are supplying a correct and valid device tree with the kernel, the existing overlay in the overlay partition doesn’t find a symbol it wants and as such invalidates the dtb in question - leading to the a nutshell the overlay modifies a device tree. I just verified that, it is 4.9.112 on mine, tooApparently Android9 bootloaders must use a device tree overlay partition and overlay the contents to the regular device tree.The rules are pretty elaborate. Software (including without limitation all object code and source code).Fastboot boot arch/arm64/boot/Image.gz -dtb dtimage -header-version 2Sending ‘boot.img’ (26726 KB) OKAY Or one can create one’s own boot image using mkbootimageMkbootimg -kernel ~/src/android_kernel_fairphone_sdm632/arch/arm64/boot/Image.gz -dt ~/src/android_kernel_fairphone_sdm632/dtimage -o boot.imgI tried that both using individual dtb’s and compiled dtb’s using dtbtool, both with v2 and v3 dtb image version (I assume v1 is a flat single dtb) I also tried a flat concatenation of all dtb’s like the kernel make file creates.So far I haven’t gotten past “dtb not found” – but if we had a working boot or recovery image from Fairphone (or offloaded from a phone somehow) we could analyze that to at least figure out which format the bootloader expects - and then figure out which dtb version we needMy bad, I could have sworn I saw a larger number. Not included in the Android Open-Source Project (and which may be updated. Version 1.4.3 - Updated adb and fastboot to API 23 version (Android 6.0) Version 1.4.2 - Updated adb and fastboot to API 21 version (Android 5.0) Version 1.4.1 - Fixed bug refusing to set PATH Version 1.4 - Fixed PATH for Windows XP (SETX missing) - Updated Google USB Driver to version.
I’m trying if that helpsGood links. Apparently recovery images are not supposed to rely on the dtbo partition but include dtb and dtbo in the boot image (to prevent bricking if the device crashes after dtbo got written but before the image got updated)If enabled, it adds a parameter to dtc adding a symbol needed for overlays to work. Start kernel given the memory address of the merged DT.So the bootloader does all this magic crap, and its up to the vendor how its implemented exactly.Edit: more interesting bg reading. Typical runtime implementation for device tree overlay in bootloader. But I have no clue what happens when you make a “try-run” withWould it load no overlays? or the one from a? or from b? or is that simply no longer supported and simply always fails?Figure 5. Is everything in the overlays and the dtb is effectively unused? or are the overlays empty and everything is in the dtb? or is it some weird mix.Another thing is, when flashing an image into boot slot a or b, the bootloader would use the respective a or b overlay partition.
extracts the kernel, ramdisk, and dtb from that boot image (basically reads it all into RAM and reads the header where what sits) loads the boot image from boot partition A We’re going to have to be careful to not brick our phonesWith a regular boot sequence from slot A, the bootloader
bootloader aborts with “error: no dtb found” bootloader might or might not try to patch the bootimg supplied dtb device tree with whatever overlay info it got from the partition or not <<< this is the question - does the bootloader read out a dtbo? if so which one? dtbo A, dtbo B, whichever is the current one?
Fastboot Source Code Manual Boot Overrides
data of the OTA update is downloaded - and potentially streamed directly to the respective slot B partitions It looks like the slots are differents?)The way an A/B update works is – assume working system is booted from slot A: (according to how I understand ) I had the same boot into recovery the first time. (I tried to flash system -it should be treble compatible-, without telling which slot… I guess the first time was on the slot b, and the 2nd -terrible- one on slot a. (only options are “try again” and “Factory data reset”)Warning: this decreased a counter, and set an “unbootable” flag getvars all now reports:As far as I understood this situation from the links above, this will prevent slot b from booting at all in the future (including “fastboot boot” commands) and including if a good image is later flashed into that slot.I don’t know if there’s a way to reset that.The bootloader behaves exactly as described inIf you force change the active slot with fastboot -set-active the “unbootable” flag is reset and the retry count is set back to 7It’s possible that manual boot overrides could be affected by an “unbootable” flag on the currently active slot, as suggested by ((sorry can#t find the link anymore))Actually, you can change its state : ~ % sudo fastboot getvar allSetting current slot to 'b' OKAY But that’s very weird that you can’t boot from slot b. I set it to slot B and tried to boot.I still cannot boot anything I give it withBut the phone is unable to boot into android from slot BIt can boot into recovery and after trying to boot into android and failing for 3 times, it enters into a minimal recovery menu instead.
(my guess) the old system in slot A is rendered non-operational(this could be implicit thanks to updated version numbers in the data partition – if that IS the case, then a device reset might actually render the old system bootable again)#6 is indeed the case - after a factory reset, I was able to boot from slot b, and indeed the phone now says it hasLinux localhost 4.9.112-perf+ #2 SMP PREEMPT Fri Nov 15 01:22: aarch64Wiping /data again and booting from slot a I getLinux localhost 4.9.112-perf+ #2 SMP PREEMPT Tue Dec 17 14:35: aarch64So indeed both slots work - the non-active one should hold the previous to latest system update, and it will not boot unless you factory-reset / wipe data first.There’s some more info which fields are used for what: github.com FairphoneMirrors/android_kernel_fairphone_sdm632/blob/master/Documentation/devicetree/bindings/arm/msm/board-id.txt * BOARD-IDThe qcom,board-id entry specifies the MSM platform and subtype revision.It can optionally be an array of these to indicate multiple hardware that useThe same device tree. the new system makes additional integrity checks - if they fail, phone boots back into working slot A the system now boots from slot B - using the NEW system after succesful update (with the old sys still running) the system is eventually rebooted
ItIs the bootloader's responsibility to pass the correct device tree to the kernel.It is expected that the qcom,board-id entry be at the top level of the deviceTree structure.
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