FP4 Root Access is possible, maybe a bit risky

Alright, switching boot slots worked, Thank you @hirnsushi!
Do you know what to do with the corrupt slot?

Commands used, for everyone interested:

Get the current active boot slot:
fastboot getvar current-slot

Select the other slot: (either “a” or “b”)
fastboot --set-active=b

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Great you got it working again :+1:
I wouldn’t worry to much about the unbootable slot, it will be reflashed with the next system update anyway. But if it bothers you, you could always extract your working slot and flash it onto the other one. I wouldn’t but you could :smirk:
Backup a copy of your working slot though, just in case.

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Is it possible to make a copy of a slot without root?

Yes, one way to do it is essentially half the root guide without actually rooting your phone:

  • Get Magisk and patch any boot.img you have lying around
  • $ adb reboot bootloader and $ fastboot boot patched_boot.img
  • $ adb shell
  • $ su and finally # dd if=/dev/block/by-name/boot_a of=/sdcard/boot_a.img for example to get boot_a
  • then just $ adb pull /sdcard/boot_a.img

I believe there is the possibility to directly dd the boot partition to your PC, don’t remember that syntax right now, sorry :man_shrugging:

Aha sounds interesting, but for my understanding the slot don’t contain the whole rom? I am on A94 boot is your earlier root guide still working? I really want to try it but i don’t want to damage my mobile. I always root all my mobile phones.

Yes, those A / B slots only contain the boot partition. When performing a system upgrade the new boot.img (so your kernel and related stuff) get written to the unused slot and at reboot your system changes to that slot. Other A / B slots (like modem, recovery…) might be updated as well, depending on the update.
I don’t know of a method to completely dump your whole system at the moment, certainly not into a reflashable custom rom kind of image. Maybe it’s possible with TWRP, haven’t looked into it. The only available TWRP for the FP4 doesn’t have access to encrypted /data anyway, so no reason to try :man_shrugging:

I can’t tell you if root still works on A94, my provider apparently doesn’t want me to update just yet. But I see no reason why it wouldn’t and early reports seem to indicate it does.
If you aren’t comfortable on the command line and with some hands on troubleshooting I wouldn’t suggest rooting at the moment, since there are still no easily flashable rom images available to recover from some worst case scenarios.

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I am familiar with Linux and commandlines input but not an expert in it. I guess I wait some more. It should be possible soon to reflash everything when things go wrong. Many thanks for the information and giving root as an option.

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I can confirm root works with A94.
As for the update not showing up you might have the same issue I had, rooting and messing with gapps basically seemed to prevent the update to show up.
I wiped my phone (after breaking too many things by trying to get Google maps to work with microG) and the second my freshly wiped device grabbed an internet connection, the update showed up…

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Yeah, I suspected that might be the case. But I’m in no rush to update, so I’ll first mess up my install enough to actually warrant a factory reset :smirk:

I have written down this procedure in some more steps as it took some tail-and-error. Feel free to provide feedback: Fairphone 4 – Root -December 2021 – Stijn D'haese

Also, any spelling errors are free of charge. :sweat_smile:

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Very clean tutorial :grinning_face_with_smiling_eyes:
Thank you for your work :stuck_out_tongue:

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thank you very much!
however unfortunately it didn´t work out for me.

previously on FP4:
I was rootet on magisk for 2 weeks with A.067 image and everything was nice with lawnchair etc.
I used Titanium Backup and it looked like it worked. Except MiXplorer - search didnt work
Deactivated majority of google apps - no MicroG

for the update:
first: I tried factory reset only. Update failed.
second: I returned to stock boot.img (my build no. is quite strange: A.081) according to your prescription.
no wifi, no sound any more.
first notice after reboot always: UI crashed (but it works fortunately)

third:
I tried to switch to slot b
after reboot its again in slot a

fourth/fifth… etc…
tried different boot images: A.091, A.094 that you posted
and from Hirnsushi´s post here
FP4 Root Access is possible, maybe a bit risky - #43 by hirnsushi)

now I am back on patched A067 Image from my first root.
still no sound and no wifi:(
And just noticed: no calls. Incoming and outgoing aaarg!

anyone has a clue?
I tried to enable WiFi with adb and the command??? lines from there:
https://code.fairphone.com/projects/fairphone-4-kernel.html

OK, let’s try to figure this out:

  • If you do a factory reset, do you have working wifi?
  • Did you flash the A.067 boot instead of booting from it? (don’t!)
  • Are you still on A.081?

Without any more information, I would suggest:

  • Do another factory reset
  • Got wifi? Stop there for now
  • If not and your build number matches with one on the kernel page flash that img.
  • Otherwise try one of the stock images I uploaded, A.081 could be boot_a :thinking:

Good luck :crossed_fingers:

Oh and changing the boot slot if you booted the other one successfully won’t work, probably Rollback-Protection

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Thanks, Hirnsushi!
I just did again a factory reset.

Still no wifi, no sound, no phonecalls

Yes, according to rar0 instructions I flashed the image. After I renamed it to A.081…
I remember your root post of warning not to flash, but I thought, rar0‘s image was different and ok to flash.
I think I flashed all three images from FP homepage:(

Still build A.081

Have you tried flashing one of the images I uploaded?
Those are the boot_a and boot_b my device shipped with and at least one of them is a build between A.067 and A.091, so may well be your A.081.

Or you can tell me the security patch level of your A.081 build (Settings->About phone->Android version->Android security update) and I can tell you which one it should be.

yes, I did. I am trying again. I used 067 for root with Magisk

Please try boot_a from my upload, that’s patch level September.

A.067 shouldn’t be used for anything apart from temporarily booting and using that to install Magisk. That build is ancient, patch level July, I’m pretty sure no device shipped with that.
When I wrote my initial instructions, that was the only image Fairphone had made available.

Android Update 5.th September
Build Fp4.FP3I.A.081.20211026

That should match the boot_a I uploaded. What happens if you flash that?
If it doesn’t work, make sure it actually gets flashed to the right slot (the slot might be chosen based on suffix :thinking: ) either rename it to your current slot or in fastboot do:

$ fastboot getvar current-slot
$ fastboot flash boot_[your_slot] path/to/boot_a.img
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I cant believe it! it worked! I did it the same way yesterday…
oh thank you so much!!!
sound works, wifi works, it believe the rest of it, too!

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