[GUIDE] The EmuNAND/Save Data Mega Guide GBATemp Doesn't Deserve

Discussion in '3DS - Flashcards & Custom Firmwares' started by mmn, Jan 13, 2015.

  1. mmn

    mmn GBAtemp Regular

    Dec 22, 2014
    United States
    The EmuNAND/Save Data Mega Guide GBATemp Doesn't Deserve
    mods feel free to edit the title

    There are way too many people running around asking the same questions
    and getting the same answers, so here we go.

    Running the exploit
    So, you finally get to use that shiny new Gateway 3DS flashcart sitting
    that's been sitting on your shelf for a month. Gateway 3.0 is out!

    If you are on firmware 4.5-9.2, here are your options:

    1. Bookmark http://go.gateway-3ds.com/ and navigate there using the web browser
    whenever you want to run the exploit
    2. Use the android app to do the above even if you don't have an internet connection
    3. Downgrade to 4.x and use the old DS Profile exploit

    BUT WAIT! Don't do any of those things yet! There are other things
    you need to know before starting. The next few sections will explain some
    info that you should know before you so much as breathe on that gateway card:

    1. How 3DS memory works
    2. What EmuNAND does
    3. Why that might cause problems
    4. How to fix those problems
    5. Everything about Save data
    6. Why you should think hard before downgrading to 4.x

    1. How 3DS memory works
    I'm going to talk relatively precisely about how things work, because I think
    people on this site generally talk very loosely about various things, and it
    confuses beginners.

    First let's talk about how the 3DS system memory works. It can basically be
    divided into two sections: "stuff that gets saved to SD", and "stuff that
    gets saved to system memory (NAND)".

    Stuff that gets saved to SD: Games, extra save data that games wish
    to save to SD

    Stuff that gets saved to system memory (NAND): System firmware,
    housekeeping info like which titles are installed, system settings, unique info
    that differentiates this 3DS system from another

    Most people already know this, but data written to SD by a certain 3DS system
    (or, a system with certain unique data in its NAND) can only be read and written
    by that same 3DS system. Unique data in that 3DS's NAND enables it to
    read/write data to a specific folder on SD. If you put the same SD card into
    another 3DS, that 3DS will have to make another folder for itself, because
    it doesn't have the same unique NAND data as the 3DS that wrote to SD
    in the first place.

    2. What EmuNAND does
    Here's pretty much what happens when you press "Format EmuNAND" in the Gateway launcher:

    1. Your SD card's partition table is wiped (data is lost)
    2. A small (~1-2GB, maybe?) partition is created
    3. A larger partition is created to fill the remaining unallocated space on the SD card
    4. An exact copy of your system NAND is made and placed on the SD card's small partition

    When you launch Gateway mode or Classic mode, the NAND copy on your SD card
    is loaded instead of the 3ds's system NAND. Pretty neat, huh! This allows
    you to update the copy of your console's firmware that lives on your SD without
    updating your console's actual firmware. It also allows really neat things,
    like the ability to install .cia files without worrying about bricking your NAND
    firmware. If you install a .cia that bricks your EmuNAND, you can just inject an
    EmuNAND backup that i'm sure you made ahead of time, and you're good to go.

    3. Why that might cause problems
    Mostly this is just why that might cause one relatively big problem. You see, your EmuNAND
    really does start off as an exact copy of your system NAND. It has the same unique info,
    the same everything. That means that when it wants to write to SD, it can and does write to
    the same SD data folder that your system nand uses. This can lead to issues with themes
    and cia installations. One of the big issues: If your system NAND and EmuNAND use the same
    data folder, going into Data Management while using system NAND will delete ALL
    .cias installed to EmuNAND, and ALL of their data. Bad bad bad.

    4. How to fix those problems
    The main issue is that your system NAND and your EmuNAND have the same unique data, so they
    both think that they are the same 3DS and write to the same data folder. You want your
    system NAND and EmuNAND to think that they are different systems, so that they will
    behave like different systems. Thankfully, performing a System Format on either
    system NAND or EmuNAND will achieve this.

    But don't do that yet. First you need to create a NAND backup and an EmuNAND backup.
    You can make a NAND backup from the Gateway launcher, and you can make an EmuNAND
    backup by using EmuNAND Tool.
    You're going to want to keep this EmuNAND backup (one of a fresh copy of your NAND),
    as well as a backup of a freshly formatted (using System Format, that is) EmuNAND,
    as well as a "recent" backup of your EmuNAND.

    After you have a backup of your system NAND and your fresh EmuNAND in a safe place,
    you can proceed to format one of the two. You're good to go, as long as you don't
    have save data from eshop games that you want to be able to use on EmuNAND.

    Here are some things to consider when deciding which NAND to format:

    1. Your friend code will change on whichever NAND you format
    2. You will not be able to access your old Streetpass Mii Plaza data
    when you're running on whichever NAND you format
    3. You will not be able to access eshop game save data when you're
    running on whichever NAND you format
    4. You will be able to use the eshop account linked with the console on EmuNAND
    regardless of which NAND you format.

    However, there is a way to keep your eshop saves. Read on if you'd like to know how.
    My recommendation is to format EmuNAND, because there's a much lower chance
    that you'll lose things from your system NAND that way.

    5. Everything about save data

    .3ds saves (all)
    These are the ez pz saves. They were made using a Gateway card running a
    .3ds rom. There are two types of rom files: Card 1 and Card 2:

    Card 1: On a retail cart, the save data would be saved to seperate memory
    outside of the game ROM itself, but still on the cart. The way Gateway handles this
    is by making a <titleid>.sav file on the SD card. This file can be transferred to
    different systems without issue.

    Card 2: On a retail cart, the save data gets stored after the ROM, in the same
    memory. I'm not 100% sure about this, but I think gateway does it in pretty much
    the same way: the save data gets saved to the .3ds file. To back this up, you need
    to use savedatafiler. Look for "CTR card"

    Just a note, savedatafiler would also work for Card 1 games, but Gateway needs
    to fix something for that to work. This means that you can't transfer saves from
    Card 1 games to .cia games. Our great savior LioMajor has found a way to
    transfer saves from card1 games to .cia! It works on MT Card, though.

    One way to fix this is to convert your Card 1 .3ds files to Card 2. It'll only work before
    you make your save though. After doing this, you can use savedatafiler to move your
    save between the .3ds and .cia. You can use this tool to convert a Card 1 .3ds file into
    a Card 2 one. Remember, you have to start a new save if you do this, so do it sooner
    rather than later!

    .cia files (all) and eshop games (<6.0.0 only, see very last "save data" section)
    I'm going to write about eshop games next, because they are the next easiest to
    understand. Eshop games, and their saves, are saved to the SD card. They can only
    be accessed by the 3DS when it's running on the NAND that they were originally
    installed with. Or, more precisely, the NAND that has the same unique info as
    the NAND that installed it. This information also holds true for .cia files
    (that's almost exactly what eshop games are).

    I'm relatively certain, though, that save data is stored encrypted
    on the SD card. If you want to back up or transfer a save, you have to use a
    program called savedatafiler. It can extract and inject saves to/from the SD card.
    It also has the ability to extract and inject saves in card 2 game carts, which I'll
    talk about further down.

    So, if you have eshop games that you want to back up the save data for,
    savedatafiler is the way to do it. Here's the process (as long as the eshop
    game and save data haven't been deleted from your SD card):

    1. Make you have savedatafiler.3ds (renamed from .csu) on the Gateway red card
    2. Backup your EmuNAND using EmuNAND tool
    3. Inject your "fresh" EmuNAND backup using EmuNAND tool. This is the one that
    has the same NAND data as your sysNAND did when you first started. If you don't
    have a backup like this, you can also try injecting your original sysNAND backup.
    4. Boot into Gateway mode
    5. For each game you want to backup, find the titleid on http://3ds.essh.co/
    6. Find the corresponding titleid slot in the first tab of savedatafiler and follow
    the directions on the top screen to backup your save (don't choose the "secure" way)
    7. The third tab of savedatafiler should show all of the data you've backed up
    8. Reinject the backup you made at step 2
    9. Install the eshop games again, either from eshop or .cia
    10. Open savedatafiler, go to the 3rd tab, and import all of the save data

    Your saves should be imported and usable! You can use a similar process for
    transferring .cia or eshop saves to a different 3DS.

    Note: If, after reading this section, you still have questions about how to use
    savedatafiler, see this awesome guide by lemanuel.

    Retail carts (<6.0.0 only, see very last "save data" section)

    If you're trying to extract a Pokemon X/Y/OR/AS save, look here.
    Otherwise, read on...

    So this issue is, uh, complicated.

    First thing's first, here's how things are supposed to work:

    1. You dump your retail cart rom (or maybe obtain it another way?)
    2. You dump your retail cart save
    3. You rename your .3ds dump to .3dz and put it on your Gateway red card
    4. You rename your .sav dump to <titleid>.sav and put it on your SD card
    5. Load up the .3ds dump

    Now I'm going to tell you that this will work with like 15% of games. Sorry :(
    This will only work if that game's save is 512kb in size. If it isn't then it'll
    read as corrupt. That's not the only issue though...

    All retail games released after 6.0.0
    In firmware 6.0.0-11, nintendo introduced a new way of encrypting save data.
    Games that include a 6.0.0-11 or higher firmware on the retail cart use this encryption.
    This is where things get dicey. One of the keys used for the encryption is loaded on
    console boot. It doesn't get reloaded when you boot into EmuNAND. This used to be
    an issue for 4.x users wanting to play retail carts with this kind of encryption.

    Gateway basically overcame this issue by making those games playable in Classic mode
    using the 4.x key loaded at boot. This meant that the games would save fine, but you couldn't
    open that save on a 9.x sysnand console, and the reverse was true as well.

    Well, now those 9.x sysnand saves will work in Classic mode, as long as your console is on
    sysnand 9.x. Gateway properly uses the 9.x key that was loaded at boot... but if you dump
    the same saves with the Gateway launcher, they won't work. I'm pretty sure this is a bug,
    and I've sent an email to Gateway about it. You can read about that here.

    There are two bottom lines here. The first is that dumped saves won't work under the
    following conditions:

    1. The game's save is not 512kb in size
    2. The game uses >6.0 encryption for saving

    The second bottom line is that you will lose the ability to play retail saves that use
    >6.0 encryption on your 3ds if you downgrade to system NAND 4.x.
    Additionally, if you have >6.0 eshop games that you started playing on a >6.0 system,
    and you weren't in gateway mode, you won't be able to keep those saves either*. This is because of
    the aforementioned mismatch in the keys used to encrypt and decrypt saves. Basically, if
    you want to continue to be able to play retail games with >6.0 save encryption, you need to
    stay on the system NAND version you are currently on. You'll need to stay at that system NAND
    version until gateway fixes all of these save compatability issues.

    THE ISSUES IN THIS SECTION ONLY APPLY TO RETAIL CARTS! See "Eshop games and .cia files" for backing up eshop/cia saves!

    * This statement seems to be contested. I can't test it myself because I don't have any eshop
    games that fit the criteria, but we have two conflicting stories about this.

    6. Why you should think hard before downgrading to 4.x
    See the last two paragraphs in the previous section.
  2. NNV

    NNV Member

    Jun 28, 2010
    United States
    Under your bed
    We're not worthy.

    This post needs to be stickied.
  3. Thomas12345

    Thomas12345 GBAtemp Advanced Fan

    Dec 1, 2014
    Quick question.... After I press "Format Emunand", GW creates an exact copy of my sysnand right? So at that point, if I immediately go into my emunand, I can play my eshop games (bought and last played on sysnand) and still have all my saves? I mean emunand and sysnand would have the same unique info right?
  4. mmn

    mmn GBAtemp Regular

    Dec 22, 2014
    United States
    Yes, that should be possible.
    Margen67 and Thomas12345 like this.
  5. Thomas12345

    Thomas12345 GBAtemp Advanced Fan

    Dec 1, 2014
    Thanks, how long did it take you to write this thing

    Also, if I boot into classic mode with 9.2 sysnand, can I make GW remember the 9.2 encryption key? Then downgrade and have GW still use the 9.2 encrytion key?

    Also after I extract my Emunand using emunand tool, can I flash it to my sysnand using Downgrade + hold up arrow? If this is possible, then maybe I can get savedatafiler to run on my sysnand and dump the save of my Pokemon Y cartridge
  6. JimMack

    JimMack Member

    Oct 22, 2006
    Great guide, condenses a lot of things that are being addressed into one topic. Do you think you could add in how playing DS games is affected by all of this stuff? I have an Acekard 2i right now, though I imagine I wouldn't need that anymore.
  7. Thomas12345

    Thomas12345 GBAtemp Advanced Fan

    Dec 1, 2014
    You can only play DS games in sysnand. You cannot play DS games in Gateway mode or in Classic mode.

    Also, if you play a DS game, you have to re-install the blue card exploit. But it shouldn't be too much of a hassle, since you'll already have the flashcart in your 3DS. Just re-install the exploit when you're done playing your DS game
    cvskid and Margen67 like this.
  8. MelonGx

    MelonGx GBAtemp Advanced Maniac

    Jan 8, 2009
    I'll say:

    If you want to dump your 3DSwares, please STAY EVERYTHING "BAD BAD BAD" IN No.3.
    Otherwise you cannot use most of the dump tools because they only support emuNAND-ID=SysNAND-ID.
  9. pu1se80

    pu1se80 GBAtemp Regular

    Dec 20, 2014
    United States
    Thanks! Definitely going to need this once N3DS support becomes available.
  10. ubergeek77

    ubergeek77 Post editing world champ.

    Dec 6, 2014
    United States
    I'm going to assume retail -> cia (even for games that don't use 6.x encryption) isn't going to happen any time soon, right?

    I'm still trying with CFW, hopefully it works at the end of it.
  11. Ralph1611

    Ralph1611 GBAtemp Maniac

    Dec 20, 2014
    United States
    Thanks.... I wanted to downgrade to 4.x but still want my >6.0 games
  12. mmn

    mmn GBAtemp Regular

    Dec 22, 2014
    United States
    Well, all you need to do to circumvent that is to restore a previous NAND backup where the ID's are the same. Backups sure are great.

    Retail -> cia works for pre-6.0.0 card 2 games. If you have an MT Card, retail -> cia works for all pre-6.0.0 games.
  13. masenko

    masenko GBAtemp Regular

    Jul 24, 2007
    United Kingdom
    Nottingham, England
    I'm planning on getting a new 3ds xl when it comes out, could i update my 3dsxl regular from 9.2 sysnand to 9.4 emunand and then use system transfer to new 3dsxl? then i could keep 3dsxl for gate and new3dsxl for real carts
  14. Zidapi

    Zidapi GBAtemp Psycho!

    Dec 1, 2002
    Less than ten lines in and I've already found your first error.

    The system versions that can exploited with Gateway 3.x range "from 4.5 and all the way up to 9.2" according to their announcement blog post.

    To further support this I'm currently running Gateway 3.0 on my 4.5 system, and am able to load emuNAND both by the DS Profile exploit and the Go web exploit.
  15. cearp

    cearp 瓜老外

    May 26, 2008
    'from me' - that makes it sound a bit like you are the only one helping people here, but still, thanks for the guide for people. but no need to say that people don't deserve it. it is cool to help but not cool to say things like that.
    do you want people to bow down and say things like 'thank you oh so much for giving this guide to us even when we don't deserve it'... jeez
  16. Zidapi

    Zidapi GBAtemp Psycho!

    Dec 1, 2002
    I concur, it reads as pretty arrogant to me. There are plenty of really helpful people here.

    That aside, I'd definitely support your guide being stickied.
  17. RikuCrafter

    RikuCrafter GBAtemp Regular

    Oct 8, 2011
    I got a reply telling me I'd be able to play my retail Persona Q and Smash etc. with EmuNAND on 9.2, with my 4.5 SysNAND. This guide says that's not possible. Could I get some clarification please as to which one is right?
  18. gudenau

    gudenau Largely ignored

    GBAtemp Patron
    gudenau is a Patron of GBAtemp and is helping us stay independent!

    Our Patreon
    Jul 7, 2010
    United States
    This needs a sticky!
  19. Jiro2

    Jiro2 GBAtemp Advanced Fan

    Mar 28, 2011
    United States
    Three questions:

    1) I am still trying to figure out how to dump the save game of Streetpass Mii Plaza (to transfer it from one machine to another). Is it possible to do this?

    2) I had a Pokemon ORAS demo on the Gateway as a .3ds. I downloaded one off the eshop and transferred the save using SaveDataFiler. This worked. My machine is SysNAND 4.1 and Em,uNAND 9.4. From what you are saying, the one on the Gateway runs using old encryption. ORAS demo uses 7.0.0 which means that the one from the eshop would use new encryption. So how did this work?

    3) Would it be possible to modify this guide to also explain the situation with NNIDS, which is almost as confusing? (I guess if you did this you'd have to rename the title)
  20. mmn

    mmn GBAtemp Regular

    Dec 22, 2014
    United States
    Alright, I fixed that, thanks.
    Oh my god I just reread that and I can't believe I actually published that.
    Needless to say, I've removed it.
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