Dual boot Android or Linux?

[gilius]

I wonder if it's possible to dual boot Android or Linux? I found out that BCDEDIT is no longer locked down in 1903 - though that seems secondary to a primary bootloader that has the Developer menu, etc. I already tried to boot the following using the ARM64 EFI file but it failed:
http://www.rodsbooks.com/refind/

No Android emulators seems to work on WOA through the x86 emulation due to problems accessing graphics acceleration.

How about passing the EFI bootloader to GRUB for Linux or Goldfish kernel for Android?

We might be able to achieve something similar to this:
https://github.com/aarch64-laptops/build

But we don't have any way to boot from USB to start with as there's no GUI for the EFI bootloader.

Currently, I can do everything on Windows except use the HSBC Online banking app - requires Android or IOS.

[blackdiamont]

I'm interested in dual boot too.
Is there any way to boot an EFI shell?

Just found this: https://www.deskmodder.de/blog/2018/11/ ... -im-video/

[gilius]

I found a guide on how the EFI bootloader works for the Lumia 950 XL, so I am planning to test EFI GRUB soon - but I think there's few areas I need to brush up on first - because it's quite technical! Will test with the normal 950 as I don't wish to ruin the XL.
https://onedrive.live.com/view.aspx?res ... LV2nY_pncM

[blackdiamont]

great! looking forward to it

[gilius]

I found out today that non-Windows EFI files cannot be booted from the Windows BCD Boot menu, and that dual booters end up replacing the Windows Boot Manager with the GRUB2 Boot Manager, which I will look into.... However, your idea about booting to the UEFI Shell is good thinking outside the box! I need to check if we can get to Advanced Startup from Windows 10 else we can get to UEFI shell by installing WSL2 - breaks the system! There might also be an official way of booting to the UEFI Shell.

[gilius]

I don't see any other choice other than to replace the main .EFI boot manager file with GRUB and then try to add the main .EFI file back as a secondary boot manager after successfully installing a Linux distro:

Briefly, edit /etc/grub.d/40_custom and add:

menuentry 'Windows 10' {
search --fs-uuid --no-floppy --set=root CC66-4B02
chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi
}
To find the UUID for the --set=root line (CC66-4B02 in the example) you use sudo fdisk -l to identify the EFI partition then sudo blkid /dev/sda1 (or whatever) to find the UUID of the EFI partition. Note it's not the Windows partition but the EFI one you need. Once you've saved the edit, run sudo update-grub to generate the /boot/grub/menu.cfg file and then restart to test.

https://askubuntu.com/questions/661947/ ... ub-os-list

However, that's providing we can indeed boot to Grub/prompt using the Lumia 950, i.e. it can handle the Grub EFI file I'm about to throw at it now...

Code: Select all

E:\EFIESP\EFI\Microsoft\BOOT>bcdedit /store BCD /enum ALL

Firmware Boot Manager
---------------------
identifier              {fwbootmgr}
displayorder            {bootmgr}

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=H:
path                    \efi\boot\bootarm.efi
description             Windows Boot Manager
locale                  en-US
inherit                 {globalsettings}
booterrorux             Simple
default                 {default}
displayorder            {default}
                        {7619dcca-fafe-11d9-b411-000476eba25f}
                        {7619dccc-fafe-11d9-b411-000476eba25f}
bootsequence            {01de5a27-8705-40db-bad6-96fa5187d4a6}
timeout                 30
displaybootmenu         Yes
persistbootsequence     Yes
custom:54000001         {0ff5f24a-3785-4aeb-b8fe-4226215b88c4}
custom:54000002         {bd8951c4-eabd-4c6f-aafb-4ddb4eb0469b}

Windows Boot Loader
-------------------
identifier              {311b88b5-9b30-491d-bad9-167ca3e2d417}
device                  ramdisk=[E:]\PROGRAMS\UpdateOS\UpdateOS.wim,{ramdiskoptions}
path                    \windows\system32\boot\winload.efi
description             Windows Update OS (Boot from WIM)
inherit                 {bootloadersettings}
osdevice                ramdisk=[E:]\PROGRAMS\UpdateOS\UpdateOS.wim,{ramdiskoptions}
systemroot              \windows
nx                      AlwaysOn
bootmenupolicy          Standard
winpe                   Yes

Windows Boot Loader
-------------------
identifier              {default}
device                  partition=E:
path                    \windows\system32\boot\winload.efi
description             Windows 10 Phone
locale                  en-US
inherit                 {bootloadersettings}
nointegritychecks       Yes
osdevice                partition=E:
systemroot              \windows
nx                      AlwaysOn
bootmenupolicy          Standard
bootstatuspolicy        IgnoreAllFailures
ems                     No

Windows Boot Application (1020000a)
-----------------------------------
identifier              {01de5a27-8705-40db-bad6-96fa5187d4a6}
device                  partition=H:
path                    \windows\system32\boot\mobilestartup.efi
description             Mobile Startup App
inherit                 {bootloadersettings}
recoverysequence        {311b88b5-9b30-491d-bad9-167ca3e2d417}
recoveryenabled         Yes
nointegritychecks       Yes

Windows Boot Application (1020000a)
-----------------------------------
identifier              {0ff5f24a-3785-4aeb-b8fe-4226215b88c4}
device                  partition=H:
path                    \windows\system32\boot\ffuloader.efi
description             FFU Loader (User Invoked)
inherit                 {bootloadersettings}
custom:26000201         Yes

Windows Boot Application (1020000a)
-----------------------------------
identifier              {7619dcca-fafe-11d9-b411-000476eba25f}
device                  partition=H:
path                    \EFI\boot\BootShim.efi
description             Windows 10
nointegritychecks       Yes

Windows Boot Application (1020000a)
-----------------------------------
identifier              {7619dccc-fafe-11d9-b411-000476eba25f}
device                  partition=H:
path                    \Windows\System32\BOOT\developermenu.efi
description             Developer Menu
nointegritychecks       Yes

Windows Boot Application (1020000a)
-----------------------------------
identifier              {bd8951c4-eabd-4c6f-aafb-4ddb4eb0469b}
device                  partition=H:
path                    \windows\system32\boot\resetphone.efi
description             Reset My Phone Application
inherit                 {bootloadersettings}
custom:26000206         Yes

EMS Settings
------------
identifier              {emssettings}
bootems                 No

Debugger Settings
-----------------
identifier              {dbgsettings}
description             Windows Debugger Settings

Global Settings
---------------
identifier              {globalsettings}
inherit                 {dbgsettings}
                        {emssettings}
bootuxtransitiontime    5000
booterrorux             Simple
extendedinput           Yes
nobootuxtext            Yes
nobootuxprogress        Yes
nobootuxfade            No
nokeyboard              Yes
mobilegraphics          Yes
custom:250000e0         1
chargethreshold         255
custom:25000511         90
bootflow                0x0
offmodecharging         No

Boot Loader Settings
--------------------
identifier              {bootloadersettings}
inherit                 {globalsettings}
advancedoptions         No
optionsedit             No

Setup Ramdisk Options
---------------------
identifier              {ramdiskoptions}
description             Ramdisk Options
ramdisksdidevice        partition=H:
ramdisksdipath          \boot\boot.sdi

Update: I replaced \efi\boot\bootarm.efi with a GRUB EFI file - but it failed to boot. And I previously tested it on Raspberry Pi to be working, so that method is out of the question.

Update: I read somewhere that bootshim.efi (secondary boot manager when selecting Windows 10 from the primary boot manager menu) is some kind of bootstrapped 64-bit version of UEFI from a 32-bit UEFI that maybe Windows Phone uses (even on the Lumia 950). It seems that bootshim.efi leads to another bootmgfw.efi that we may look to replace with Grub instead.

Update: bootshim.efi leads to Partition41 - another EFI System Partition for Windows 10 specifically - this is looking promising!

[blackdiamont]

Great job! Well, if you're going to replace the bootmgr or main EFI file with a UEFI-Shell(try 64 and 32bit) ... do you think this will work?

[gilius]

SUCCESS - I got it to boot the GRand Unified Bootloader!!! That means we can do anything now... (except type )

[The_GTA]

Good job, gilius! I was wondering too if another ARM64 OS could be booted out of the box on Lumia smartphones. Inside the article, the tweet did imply that touch worked. Wondering if that is really is the case or if we could get in touch with the guy that did it?

[gilius]

Thanks! Yeah, it's obvious now that Ben @ Imbushuo had done all the hard work in chainloading from the Lumia's native UEFI system to a proper one (EFI System Partition 41) where we can run anything we like! And I did drop Ben a line today incidentally, so if he's not too busy he might get back with some additional pointers.

Touch will work for sure inside a main Linux distro - possibly even inside an installer too - but since the disk is GPT we cannot run the Ubuntu installer from the HD; instead, I will look at writing a preinstalled version and trying to get GRUB to point to the rootfs partition, etc.

As long as we only work with Partitions 41 and 42 - and don't delete the Data partition (or anything before it) - I think we should be safe. Just now I deleted them both then extended the Data partition to use the remaining disk space before using WOA Deployer to redeploy WOA and put everything back to how it was prior to messing around with GRUB.

[gilius]

Unfortunately, this is not looking as promising as I thought...

I got Ubuntu Server 19.04 to boot up and can navigate the menus, but it crashes shortly after I choose Ubuntu (or Recovery mode); probably related to these ARM64 bugs:
https://bugzilla.redhat.com/show_bug.cgi?id=1323239

Edit: GRUB probably needs a new UUID or some workaround:
https://askubuntu.com/questions/171446/ ... er-machine

grub.cfg looks like this:

Code: Select all

search.fs_uuid a738cc26-615b-4201-9e5c-f90dc5ba8f9a root hd0,gpt42 
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg

But the UUID is from a different HD I backed up from.

Edit: I'm not convinced it is a UUID problem. Maybe a bug on the Lumia system or something to do with Microsoft blocking it from booting.

[The_GTA]

Do you have anything prepared that we can try ourselves to get up-to-speed with how far you have come? Maybe somebody else could quickstart and find workarounds if you posted this "preinstalled version". Other than that, great job for getting this far nonetheless But you gotta admit that Linux is possible because the tweet does show a GUI environment.

[blackdiamont]

Again great job @gilius!
Is it save to replace the efi files and going back without any chance of bricking the device?
If so then I would try myself to boot debian

[gilius]

OK, I'll write a guide tonight - but I can't promise my methods are the most efficient - and it's harder to setup an ARM version of a distro compared to X64/X86, etc. You guys have access to a Raspberry Pi?

[dudemo]

OK, I'll write a guide tonight - but I can't promise my methods are the most efficient - and it's harder to setup an ARM version of a distro compared to X64/X86, etc. You guys have access to a Raspberry Pi?

I have a Pi 3, a Pi 4 (4Gb), a Pi Zero, a Rock64 (4Gb), and a Banana Pi M3. You write it, I'll try it.

[blackdiamont]

Just bought a raspi 4 to test WoA on it

[dudemo]

Just bought a raspi 4 to test WoA on it

Last I knew WoA wasn't available for the Raspberry Pi 4. It's made for the 3, but not the 4.

[blackdiamont]

Shouldn't make any difference since the SoC is similar
Maybe the USB3 chip could be a problem, but I don't think so ^^

[gilius]

UEFI support for WOA on the RPi4 it not ready yet:
https://github.com/andreiw/RaspberryPiPkg/issues/130
https://github.com/andreiw/RaspberryPiP ... -527246285

But see my guide for using KVM on Raspberry Pi 4:
https://www.raspberrypi.org/forums/view ... p?t=248345

Will help when I finish optimizing Windows 10 Lite for ARM, as it's much quicker to run on lesser devices:
https://discourse.pi64.win/t/windows-10 ... xl-wip/418

For this Linux/Lumia guide you are going to ideally need the Raspberry Pi 3 UEFI - or you could use a VM in software simulation mode on a normal PC running Windows/Linux - but it's very tough to run an ARM64 VM (see above KVM guide as it also applies to ARM64 VMs in general as well as https://www.raspberrypi.org/forums/view ... p?t=224057)

First thing to do then is prepare a memory card with UEFI drivers for the Raspberry Pi so you can boot some Linux installers in UEFI mode:
Micro SD card inside USB adapter (MBR with 64-bit Tiano Core UEFI for the Raspberry Pi 3 & empty partition for Windows paging file if ever you install WOA)

diskpart
list disk
select disk X (micro sd)
clean
convert mbr
create partition primary size=124
format fs=fat32
active
assign letter q
create partition primary
format fs=ntfs quick
assign letter r
exit

copy the EFI files to q:\ from https://github.com/andreiw/RaspberryPiP ... C5/RELEASE
bootcode.bin
fixup.dat
RPI_EFI
start.elf
config.txt
“arm_control=0x200
enable_uart=1
armstub=RPI_EFI.fd
disable_commandline_tags=1
disable_splash=1
disable_overscan=1
max_usb_current=1”

When you boot the micro SD card inside the Pi, always begin by pressing Esc to get to the UEFI menu. Here, you can change to max CPU Clock override (device manager > Raspberry Pi Configuration > Chipset Configuration) and also reduce the resolution (Display settings under the same menu) if you like. When you are ready to boot either a live CD or written OS disk from USB then you can select the device from Boot Manager - but note that hub-powered SSDs can take a while before they show up - so you need to keep exiting and entering the Boot Manager menu till you see the SSD.

This initial Linux experiment is going to require 1 x USB for installing a Linux ISO live CD as well as 1 x SSD (hub-powered) to write the Linux distro.

[gilius]

1) Download the Debian mini.iso and write it to the USB using Rufus on your main Windows PC:
https://d-i.debian.org/daily-images/arm ... y/netboot/


2) Clean your SSD and convert to GPT:


3) Boot up the Debian installer in the Rpi3 and write it to the SSD via Andreiw's UEFI Bios installed to Micro SD - remember to hit ESC and go to Boot Manager to boot USB Device. Near the end of the process you will need to choose a desktop environment - but sadly I missed this part in my attempt so I will not have touch if we ever this thing to properly boot up on the Lumia. Note: most older distros require a USB Ethernet adapter - but not Debian nor Ubuntu 19.10:


4) Once the install completes then take out the SSD from the Pi and connect it to your main Windows PC:

Code: Select all

C:\Windows\System32>diskpart

Microsoft DiskPart version 10.0.18362.1

Copyright (C) Microsoft Corporation.
On computer: GILIUS-W10

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online         1907 GB  1024 KB        *
  Disk 1    Online         5589 GB  1024 KB        *
  Disk 2    Online         5589 GB      0 B        *
  Disk 3    Online          119 GB      0 B        *

DISKPART> select disk 3

Disk 3 is now the selected disk.

DISKPART> list partition

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
  Partition 1    System             512 MB  1024 KB
  Partition 2    Unknown            117 GB   513 MB
  Partition 3    Unknown            881 MB   118 GB

DISKPART> select partition 1

Partition 1 is now the selected partition.

DISKPART> assign letter p

DiskPart successfully assigned the drive letter or mount point.

DISKPART> exit

Leaving DiskPart...

C:\Windows\System32>p:

P:\>cd efi

P:\EFI>dir
 Volume in drive P has no label.
 Volume Serial Number is A9CC-56BF

 Directory of P:\EFI

25/11/2019  19:47    <DIR>          .
25/11/2019  19:47    <DIR>          ..
25/11/2019  19:47    <DIR>          debian
               0 File(s)              0 bytes
               3 Dir(s)     532,193,280 bytes free

P:\EFI>mkdir boot

P:\EFI>copy debian\*.* boot\
debian\shimaa64.efi
debian\grubaa64.efi
debian\mmaa64.efi
debian\fbaa64.efi
debian\BOOTAA64.CSV
debian\grub.cfg
        6 file(s) copied.

P:\EFI>cd boot

P:\EFI\boot>dir
 Volume in drive P has no label.
 Volume Serial Number is A9CC-56BF

 Directory of P:\EFI\boot

25/11/2019  20:17    <DIR>          .
25/11/2019  20:17    <DIR>          ..
25/11/2019  19:47           918,872 shimaa64.efi
25/11/2019  19:47         1,693,040 grubaa64.efi
25/11/2019  19:47           884,952 mmaa64.efi
25/11/2019  19:47           819,152 fbaa64.efi
25/11/2019  19:47               110 BOOTAA64.CSV
25/11/2019  19:47               126 grub.cfg
               6 File(s)      4,316,252 bytes
               2 Dir(s)     527,835,136 bytes free

P:\EFI\boot>rename grubaa64.efi bootaa64.efi

5) You can now boot the thing up in your Pi if you like via Andreiw's UEFI - or just proceed to the next stage.

6) You need to shrink that partition 2 down using either GPARTED on a linux system or Mini Tool Partition wizard on a Windows system:
Partition ### Type Size Offset
------------- ---------------- ------- -------
Partition 1 System 512 MB 1024 KB
Partition 2 Unknown 117 GB 513 MB
Partition 3 Unknown 881 MB 118 GB

Sometimes it might fail first time to shrink and you might need a few GB extra - probably because it discovers a GPT partition table near the end, which I also heard exists and needs to be included in any backup. Also move the swap file to the left - or possibly even delete it:



7) Back on the Windows PC with the shrunken SSD plugged in and your Lumia 950/XL at the mass storage screen via developer menu - having previously deployed WOA - you want to clone the 3 partitions from the SSD to the end of your phone after deleting the last 2 partitions. This is all achieved using Macrium Reflect Free Edition:


Delete the last 2 partitions one at a time - but don't touch data or any partitions before 41


Drag over the 3 partitions to the end of the phone disk and then write the changes:


Unfortunately, that debian clone has the same problem as the ubuntu clone - both boot to the main menus but crash at the "EFI stub" part - so require tinkering in terms of GRUB whilst booted on the Pi - probably something simple to do with UUIDs or creating a different kind of GRUB menuentry.

8) To restore the phone go back to Mass Storage Mode. In Disk Management delete the last 2 partitions, but then the EFI one (Partition 41) will need to be deleted in Diskpart:

Code: Select all

C:\Windows\System32>diskpart

Microsoft DiskPart version 10.0.18362.1

Copyright (C) Microsoft Corporation.
On computer: GILIUS-W10

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online         1907 GB  1024 KB        *
  Disk 1    Online         5589 GB  1024 KB        *
  Disk 2    Online         5589 GB      0 B        *
  Disk 3    Online          119 GB   112 GB        *
  Disk 4    Online           29 GB    17 GB        *

DISKPART> select disk 4

Disk 4 is now the selected disk.

DISKPART> list partition

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
  Partition 1    Unknown             512 B    32 KB
  Partition 2    Primary              8 MB  2048 KB
  Partition 3    Unknown           1536 KB    10 MB
  Partition 4    Unknown           1536 KB    12 MB
  Partition 5    Unknown           1536 KB    14 MB
  Partition 6    Unknown             16 KB    16 MB
  Partition 7    Unknown           1024 KB    18 MB
  Partition 8    Unknown            128 KB    20 MB
  Partition 9    Unknown            256 KB    22 MB
  Partition 10   Unknown            256 KB    24 MB
  Partition 11   Unknown             16 KB    26 MB
  Partition 12   Unknown             16 MB    28 MB
  Partition 13   Unknown             16 KB    44 MB
  Partition 14   Unknown            256 KB    46 MB
  Partition 15   Unknown            256 KB    46 MB
  Partition 16   Unknown            256 KB    48 MB
  Partition 17   Unknown             16 KB    50 MB
  Partition 18   Unknown           1024 KB    52 MB
  Partition 19   Unknown            512 KB    54 MB
  Partition 20   Unknown             48 KB    56 MB
  Partition 21   Unknown           2048 KB    58 MB
  Partition 22   Unknown            500 KB    60 MB
  Partition 23   Unknown           1024 KB    62 MB
  Partition 24   Unknown            500 KB    64 MB
  Partition 25   Unknown            512 KB    66 MB
  Partition 26   Unknown             16 MB    68 MB
  Partition 27   Unknown           1024 KB    84 MB
  Partition 28   Unknown            512 KB    86 MB
  Partition 29   Unknown             48 KB    88 MB
  Partition 30   Unknown           2048 KB    90 MB
  Partition 31   Unknown            500 KB    92 MB
  Partition 32   Unknown           1024 KB    94 MB
  Partition 33   Unknown            500 KB    96 MB
  Partition 34   Unknown            512 KB    98 MB
  Partition 35   Unknown             16 MB   100 MB
  Partition 36   Unknown              8 MB   116 MB
  Partition 37   Primary             32 MB   124 MB
  Partition 38   Primary           6144 KB   156 MB
  Partition 39   Primary           2933 MB   168 MB
  Partition 40   Primary              8 GB  3104 MB
  Partition 41   System             512 MB    11 GB

DISKPART> select partition 41

Partition 41 is now the selected partition.

DISKPART> delete partition override

DiskPart successfully deleted the selected partition.

9) Extend the Data partition - you can then reinstall Windows 10 on ARM using WOA Deployer:



Let me know if you guys manage to find the EFI/Grub fix causing the kernel panic on both Debian and Ubuntu (haven't tried any others so far)!

EDIT: I'm starting to think it's not a GRUB problem at all - but a limitation to do with the EFI Firmware - only Ben can confirm for sure.

[gilius]

Explosive news: rEFInd boot manager actually works on partition 41 and apparently has touch support! About to test Ubuntu from there...

Update: same type of crash happens - even when booting Ubuntu using Refind boot manager.

[blackdiamont]

Nice!!!! I'll take a look as soon as I can! Thank you for this great guide gilius!!!

[gilius]

NP - it's always a good IT exercise to learn more about the Lumias, bootloaders and different approaches to handling partitions - even though Linux isn't properly bootable yet. For example, I'm now more confident to try a manual install of WOA next.

BTW, Ben (Bingxing Wang) got back to me this morning:

For booting Linux, you have two options:

• Use Little Kernel (LK) similar to some Android phones: retrieve the required BootShim from https://dev.azure.com/imbushuo-personal ... t/BootShim and https://dev.azure.com/imbushuo-personal ... ootShimPkg. (BootShim chainloads BootShimPkg, then chainloads LK)

• If you are using Lumia 930, consider https://github.com/rickliu2000/Lumia930Pkg. You might want to contact the author for further details.

Also for booting Linux on 950XL on the 64bit UEFI, you need to disable acpi "acpi=off". Then you need to load a proper device tree.

Anyone know how to compile those?

[blackdiamont]

Compiling a kernel isn't a big deal but crosscompiling is a bit .... ugh ...
I never compiled android, because it looks to freaking time consuming and weird =D

If you are using Lumia 930, consider https://github.com/rickliu2000/Lumia930Pkg. You might want to contact the author for further details.

Looks interesting

[The_GTA]

BootShim:

BootShim.zip

(23.38 KiB) Downloaded 700 times

BootShimPkg:

BootShimPkg.zip

(22.04 KiB) Downloaded 730 times

My head hurts... Compiling those things is the least I will do for you guys.

Both are compiled for 32bit ARM. Are these all that you need? And what about this LittleKernel? Can you do that yourself?

[gilius]

Good stuff, GTA! That's the hardest part out of the way, as I haven't compiled a program in 20 years except for Linux makefiles! I wouldn't even know what compiler to use for Ben's handywork or how to setup the right environment, etc.

I found this info about LittleKernel - perhaps BootShim is a port of that:
https://forum.xda-developers.com/window ... l-t3782093

So that just leaves "acpi=off" (anything for that in the source code?) and "loading a proper device tree"? Could Ben be referring to a DTB file made especially for the Lumia 950 XL that must be present somewhere...? How about those ELF files - could they be DTBs?

[The_GTA]

I feel like an ancient shaman cooking up some ridiculous EFI things.

Turns out I managed to create EFI binaries with less dependencies on Linux stuff (at least some Ubuntu nerd wrote it down this way). So I recompiled BootShimPkg with arm-none-eabi-gcc and for the heck of it compiled LK aswell.

littlekernel_none_eabi.zip

(156.26 KiB) Downloaded 646 times

BootShimPkg_none_eabi.zip

(21.8 KiB) Downloaded 707 times

Hoping that you get some interesting stuff done with these

Since those are both 32bit this acpi=off stuff does not matter for us, right? Unless you want to do all this procedure for ARM64 aswell...

[gilius]

Much appreciated for all your efforts so far on this; cheers to GTA in the name of progress, for this thread is certainly edging in the right direction!

I'm still confused as to which components in the Lumia 950 XL - coupled with additional ones by the WOA Deployer project (Ben's EFI dependencies being at the core of that) - are ARM32 vs. ARM64? Presumably since we are primarily running Windows 10 on ARM via BootShim chainloaded to the secondary Windows Boot Manager @ Partition 41 then that (BootShim) would be compiled in ARM64? And maybe Windows Phone and the Developer menu are ARM32 via the primary Windows Boot Manager? So if you compiled them in ARM32 - and definitely not x86, right(?) - then we might be able to run a 32-bit ARMv7 Linux distro - equivalent to Windows RT or Windows S? Purely speculation of course.* The WOA team @ Microsoft tried to encourage developers to use Visual Studio and to simply switch the architecture to ARM64 when compiling:


*Or it might be that everything about these packages are ARM32, but they happen to be capable of running ARM64 operating systems?

I'll try to deep dive the Lumia components to see if we can deduce more on the bigger picture of how everything fits together in this tremendous gift that is the Lumia 950 XL!

[The_GTA]

Good idea. Not sure about the Lumia 950 boot architecture. My assumption was that WoA did boot from a 32bit UEFI but because it was kernel-mode code it could just switch into 64bit mode. But I am in no shape or form experienced in ARM32/ARM64 assembly. On a related side-node, imbushuo's BootShim project did come with only a ARM 32bit compilation mode, so I assume that ARM 32bit is the way it was meant to be compiled.

Just hit me up if you need the ARM64 versions. Will see what I can do.

EDIT: to answer the question about loading a "device tree" I found this interesting guide on Github. While it is not complete anymore (imbushuo has long since removed files that were linked in the guide) it does claim to have complete steps for Linux booting. Maybe we can build on these steps to even allow Ubuntu?

[gilius]

OK cool - will hopefully be in a position this weekend to have a tinker and see where it leads - thanks for everything!