Full OS boot from SD (working)

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This is one of those things that I've always assumed would work, but I don't think I've seen anyone actually confirm it or talk about it yet. Before doing any of this I did a clean wipe of everything, just to avoid confusion on my part.


Step 1) I DD'ed the entire filesystem to an 8GB microSD that I have.
Step 2) Mounted p1 from SD (which is a copy of P1 from internal)
Step 3a) Pulled ramdisk
Step 3b) Extracted ramdisk
Step 3c) Changed all mmcblk0 refs to mmcblk1 in init.rc
Step 3d) Recompiled ramdisk
Step 3e) Pushed ramdisk back to p1 on SD
Step 4) Shut down Nook, reboot, confirm via mount command that all mounted volumes are mmcblk1

As I said, this is nothing revolutionary, but I figured it could be good for testing, especially if anyone wants to take a shot at a potentially dangerous mod like recovery or installing a fresh /system. Also, if I ever seriously messed up my internal memory, I would hope to be able to somehow recover by booting via the SD and being able to DD to the internal memory that way.

Very interesting. Thanks for the effort. Might be worth saving the image in case someone actually DOES brick their nook.

I'm curious as to the specifics. Aren't there several filesystems on the device? What did you do to pull/extract/recompile the ramdisk?

APKs

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Are you able to install apk files to the emulated rom/nand on SD card...

also are you able to mount an extra partion on the card....

Thanks

"I would hope to be able to somehow recover by booting via the SD and being able to DD to the internal memory that way"

That will be great if we can push those files back to NAND

FYI, Holding just power + Nook buttons for about 15-20 sec will bring up the factury reset screen.

Originally Posted by nook'r

Are you able to install apk files to the emulated rom/nand on SD card...

I haven't yet, but I don't see why not. Nothing especially different about it as opposed to the internal filesystem.

Originally Posted by nook'r

also are you able to mount an extra partion on the card....

Right now I left vold alone, so it rather stupidly mounts p1, which contains all the critical stuff. I don't see any reason why vold couldn't be made to point to another seperate partition. (which is what I did with some other trials when using the internal ramdisk to boot to /system on the SD - left p1 as a "sdcard" partition)

Originally Posted by nook'r

"I would hope to be able to somehow recover by booting via the SD and being able to DD to the internal memory that way"

That will be great if we can push those files back to NAND

I've backed up my own partitions individually. I suppose if I zero'd empty space and gzipped I could probably find some way to write the entire partition table to somewhere.

Would this be useful to someone who would want to dual boot with Ubuntu or MeeGo?

Could this be used to "dual boot" the fully stock Nook in store and then from card when you want to be free?

Homer

Originally Posted by Homer_S_xda

Could this be used to "dual boot" the fully stock Nook in store and then from card when you want to be free?

Homer

This can be used for whatever you want to use it for. I've been running this way for quite a while, and everything works just as it would if you're running from the internal. It's just like dual booting on your PC.

The first (that I saw) and best documentation for setting this up can be found at:

http://blog.fsck.com/

Originally Posted by axe2

This can be used for whatever you want to use it for. I've been running this way for quite a while, and everything works just as it would if you're running from the internal. It's just like dual booting on your PC.

The first (that I saw) and best documentation for setting this up can be found at:

http://blog.fsck.com/

This is intriguing.

I would love to run everything off a micro sd and then pop it out to put it back to stock.

Would a 1GB micro sd work ok for this?

Someone needs to come up with an automated way to do this. That would be awesome.

Originally Posted by moovius

This is intriguing.

I would love to run everything off a micro sd and then pop it out to put it back to stock.

Would a 1GB micro sd work ok for this?

Someone needs to come up with an automated way to do this. That would be awesome.

1GB is going to be too small to hold the whole system, but 4GB should work.

It should be something that would be scriptable assuming that the required tools exist on the standard rom, but I don't know if the tools are on there.

You could probably get to 1 GB if you dumped all the recovery junk and made media and data tiny. I'm trying to think if there's anything earing up tons of space besides /system.

Of course, just because you can doesn't mean you should.