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[MOD][FEB 10] MultiROM v33

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MultiROM is one-of-a-kind multi-boot mod for Nexus 6. It can boot any Android ROM as well as other systems like Ubuntu Touch, once they are ported to that device. Besides booting from device's internal memory, MultiROM can boot from USB drive connected to the device via OTG cable. The main part of MultiROM is a boot manager, which appears every time your device starts and lets you choose ROM to boot. You can see how it looks on the left image below and in gallery. ROMs are installed and managed via modified TWRP recovery. You can use standard ZIP files to install secondary Android ROMs and MultiROM even has its own installer system, which can be used to ship other Linux-based systems.

* Multiboot any number of Android ROMs
* Restore nandroid backup as secondary ROM
* Boot from USB drive attached via OTG cable

You can also watch a video which shows it in action.

It _is_ dangerous. This whole thing is basically one giant hack - none of these systems are made with multibooting in mind. It is no longer messing with data partition or boot sector, but it is possible that something goes wrong and you will have to flash factory images again. Make backups. Always.

1. Via MultiROM Manager app
This is the easiest way to install everything MultiROM needs. Install the app and select MultiROM and recovery on the Install/Update card. If the Status card says Kernel: doesn't have kexec-hardboot patch! in red letters, you have to install also patched kernel - either select one on the Install/Update card or get some 3rd-party kernel here on XDA. You are chosing kernel for your primary ROM, not any of your (future) secondary ROMs, so select the version accordingly.
Press "Install" on the Install/Update card to start the installation.
2.Manual installation
Firstly, there are videos on youtube. If you want, just search for "MultiROM installation" on youtube and watch those, big thanks to all who made them. There is also an awesome article on Linux Journal.

MultiROM has 3 parts you need to install:
  • MultiROM ( - download the ZIP file from second post and flash it in recovery.
  • Modified recovery (TWRP_multirom_shamu_YYYYMMDD.img) - download the IMG file from second post and use fastboot or Flashify app to flash it.
  • Patched kernel - You can use either one of the stock ones in second post or third-party kernels which include the patch, you can see list in the second post. Download the ZIP file and flash it in recovery.
You current rom will not be erased by the installation.
Download links are in the second post.

Adding ROMs
1. Android
Go to recovery, select Advanced -> MultiROM -> Add ROM. Select the ROM's zip file and confirm. As for the space, clean installation of stock 5.0 after first boot (with dalvik cache generated and connected to google account) takes about 1 GiB of space.

Using USB drive
During installation, recovery lets you select install location. Plug in the USB drive, wait a while and press "refresh" so that it shows partitions on the USB drive. You just select the location (extX, NTFS and FAT32 partitions are supported) and proceed with the installation.
If you wanna use other than default FAT32 partition, just format it in PC. If you don't know how/don't know where to find out how, you probably should not try installing MultiROM.
If you are installing to NTFS or FAT32 partition, recovery asks you to set image size for all the partitions - this cannot be easilly changed afterward, so choose carefully. FAT32 is limited to maximum of 4095MB per image - it is limitation of the filesystem, I can do nothing about that.
Installation to USB drives takes a bit longer, because the flash drive is (usually) slower and it needs to create the images, so installation of Ubuntu to 4Gb image on my pretty fast USB drive takes about 20 minutes.
Enumerating USB drive can take a while in MultiROM menu, so when you press the "USB" button in MultiROM, wait a while (max. 30-45s) until it searches the USB drive. It does it by itself, no need to press something, just wait.

Updating/changing ROMs
1. Primary ROM (Internal)
  • Flash ROM's ZIP file as usual, do factory reset if needed (it won't erase secondary ROMs)
  • Go to Advanced -> MultiROM in recovery and do Inject curr. boot sector.
2. Secondary Android ROMs
If you want to change the ROM, delete it and add new one. To update ROM, follow these steps:
  • Go to Advanced -> MultiROM -> List ROMs and select the ROM you want to update.
  • Select "Flash ZIP" and flash ROM's ZIP file.

Source code
MultiROM - (branch master)
Modified TWRP - (branch master)
Kernel w/ kexec-hardboot patch -

I'd be glad if you could spare a few bucks. You can use either paypal or Bitcoins, my address is 172RccLB2ffSnJyYwjYbUD3Nx4QX3R8Ris
Thanks to all donors, it is much appreciated
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6th April 2015, 07:08 PM |#2  
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1. Main downloads

Modified recovery (based on TWRP): TWRP_multirom_shamu_20160210.img
MultiROM Manager Android app: Google Play or link to APK

Kernel w/ kexec-hardboot patch (Stock 5.0 and 5.0.1):
Kernel w/ kexec-hardboot patch (Stock 5.1):
Kernel w/ kexec-hardboot patch (Stock 5.1.1):
Kernel w/ kexec-hardboot patch (Stock 6.0 and 6.0.1):
Kernel w/ kexec-hardboot patch (CM 12.0):
Kernel w/ kexec-hardboot patch (CM 12.1):
Kernel w/ kexec-hardboot patch (CM 13.0):
You need to have kernel with kexec-hardboot patch only in your primary ROM!

2. third-party kernels with kexec-hardboot patch
Nicely ask your kernel developer to merge kexec-hardboot patch.
3. Uninstaller

MultiROM uninstaller:
Flash this ZIP file to remove MultiROM from your device. It will erase all secondary ROMs. If you don't want MultiROM menus in recovery, re-flash clean TWRP, but it is not needed - those menus don't do anything if MultiROM is not installed.
4. Flashable factory images ZIPs
I usually release flashable ZIP files based on new factory images from Google, so that you can have clean stock ROM as a secondary system in MultiROM. They are not rooted, no anything, except for occasional small tweaks to make rooting with SuperSU possible. You can find them in this folder on basketbuild or dev-host.

MultiROM v33
* Updates for Android 6.0 compatibility

MultiROM v32b
* Add support for Android M preview (MPZ44Q). SuperSU 2.46 doesn't work on M
  and breaks boot - don't flash it!

MultiROM v32a
* Fix pattern encryption password incorrectly reporting "invalid password"
  when the pattern overlaps itself

MultiROM v32
* First stable release for shamu

* Fix ZIP selector being set to wrong storage after flashing ZIP to a
  secondary ROM

* Fix confusing "Unable to mount..." error message
* Fix flashing of some kernels into secondary ROMs (e.g. Elite kernel)

* Update to TWRP 3.0.0 (big thanks to nkk71 for doing most of the work)
* Use Material theme made by z31s1g - thanks!
* Fixes for 6.0 compatibility
* Fixes for SuperSU compatibility. Use BETA 2.67-20160203160253 ( ) or newer!

* Update to TWRP 2.8.7
* Add option to duplicate secondary ROM into "Swap ROMs" section

* First stable release for shamu
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6th April 2015, 07:09 PM |#3  
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FAQ and other notes
Device encryption
Since v32, MultiROM supports encryption on this device (it has to be added for each device separately). It works only with Android-based secondary ROMs and the secondary ROMs don't know the device is encrypted, so they would allow you to encrypt the device again - do not do that. If you're using password, pin or pattern for the encryption, MultiROM will ask you for the password on boot. If you're booting the primary ROM, then Android will ask you for the password _again_ - unfortunately, there is no way for me to pass the "unencrypted" status to Android. If you're booting secondary ROM, MultiROM will ask you for the password again after the reboot - that's because I have to unencrypt the /data partition after the ROM's kernel is loaded.

I could omit the second password prompt when booting secondary ROM by temporarily saving the password somewhere, but that's obviously unsafe. So is using encryption with unlocked device though, so I might add this later.
About security
In order to make multi-booting possible, MultiROM has to sacrifice some security measures. Firstly, on secondary Android ROMs, /system is not mounted read-only. While there are other things preventing malicious software from messing with /system, this might potentialy make it easier for such software to attack that system.
What do the ROMs share?
All ROMs are separate, except /sdcard, which is shared between all Android ROMs.
How many ROMs can I have?/Where are the ROMs stored?
You can have as many ROMs as you can fit in your /sdcard. All the ROMs are stored in /sdcard/multirom/roms or on an USB drive. This folder is unaccessible in Android, to prevent mediascanner from scanning it. You can either in recovery, or obtain root and go to /data/media/0/multirom/roms.
Can I have different versions of Android working alongside
Yes. As long as you select "Don't shere kernel" when installing the secondary ROM, the systems are separated.
MultiROM recovery says it's Why isn't it updated to 2.6.3.*highernumber*?
It is, it just shows wrong version.
The menu with all the ROMs won't show up during boot, how to fix it?
Either re-flash the MultiROM zip or go to recovery, Advanced -> MultiROM -> Inject curr. boot sector.

The reason for this is that something rewrote your boot.img, which happens for example when you flash a kernel. MultiROM's boot menu is part of the boot image, so it has to be added into it again.
Will you port MultiROM to device X?
No, probably. I won't port MultiROM to any device I don't own, because it is very difficult to provide the level of support I want to provide if I can't test things myself, as proven by the Nexus 4 port. I'd like to support more devices, but it is also very unsatisfying to work on code for device I don't have - I invest hours upon hours of time for free into it, and then I can't even see it running on the device, so...why..bother..?
I'll probably keep buying Nexus devices and keep porting MultiROM to those myself, but I can't buy every single device - I'm still a student, all my existing devices were bought using some kind of money grant or donations from users.
But, you can port it yourself, the wiki should give you at least some idea how to do that:
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6th April 2015, 07:54 PM |#4  
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At last, multirom is official for nexus 6!

Congrads Tasssadar!
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6th April 2015, 08:58 PM |#5  
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Been testing this since its release. Always been awesome! Thanks Tasssadar. Been using MultiROM for awhile now.
6th April 2015, 09:08 PM |#6  
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So glad to see this finally get a thread. So thankful for your work Tasssadar. Innovative as well as functional, love it!

I've been waiting until our device got a thread to ask this question, anyone who knows, feel free to answer - Some ROMs require a wipe of /system in order to boot. I believe I understand the flashing instructions as I have read them numerous times - you factory data reset to clean flash, wipe cache to dirty flash. How would one boot a ROM that requires a wipe of /system into a secondary ROM slot? Or for those users who mess with a lot of /system stuff and like to wipe on every flash, is there a way to do this for secondary ROMs that I simply missed? Or should something about the way MultiROM is structured, i.e. "All ROMs are separate" from the FAQ, eliminate issues in terms of needing to wipe /system for secondary ROMs? I figure I would rather ask a question I don't need to than find out the hard way given this is not standard flashing and thus not inherently obvious.
6th April 2015, 09:46 PM |#7  
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Nice work, like with your previous Versions. This will be awesome to use especially with the 64GB variant!
6th April 2015, 09:54 PM |#8  
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Amazing work. Thanks for all of it. Hope you got your N6 RMA back!
6th April 2015, 10:17 PM |#9  
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I had this problem with the test releases also, but decided to keep it to myself since it was a test release, but the "key press to launch multirom" option in TWRP doesn't work. We obviously can't use volume down because that boots you into the bootloader, I've tried holding volume up while the phone is off and then pressing the power button, but it just continues to boot my rom.
6th April 2015, 10:34 PM |#10  
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Originally Posted by brando56894

I had this problem with the test releases also, but decided to keep it to myself since it was a test release, but the "key press to launch multirom" option in TWRP doesn't work. We obviously can't use volume down because that boots you into the bootloader, I've tried holding volume up while the phone is off and then pressing the power button, but it just continues to boot my rom.

That's exactly what testing releases are for - finding bugs and fixing them. Next time you spot something like that, report it right away, otherwise I might not even know about the problem

But somebody else reported the key-based autoboot not working, and unfortunately, on shamu, there is no way to tell if a key has been pressed before the kernel has booted up. I could add a short period of time when you could press the key and it would work, but then it would be the same as time-based autoboot. I will hide that option in next recovery release, so it doesn't mislead people.
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7th April 2015, 02:21 AM |#11  
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Awesome work
I'm waiting for miui / any other good custom ROM port for nexus 6
Atm we have only cm12 /stock based roms :3 .

Anyway thanks for bringing this to n6
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