1. John_Drek

    OP John_Drek Newbie
    Newcomer

    Joined:
    Apr 30, 2018
    Messages:
    9
    Country:
    United States
    I'm really really sorry if this is a useless thread but I don't know who else to talk to about this if this is even possible. Is it possible that you can modify a nand dump and downgrade it then restore the nand just like how you are able to downgrade the Nintendo Wii (Just an example).
     
  2. Zyvyn

    Zyvyn GBAtemp Advanced Maniac
    Member

    Joined:
    Aug 9, 2017
    Messages:
    1,945
    Country:
    United States
    with the access that we have for sure though it would be far in the future would just require a way to bypass the fuses
     
    andijames likes this.
  3. ThisIsDaAccount

    ThisIsDaAccount GBAtemp Maniac
    Member

    Joined:
    Apr 8, 2016
    Messages:
    1,159
    Country:
    United States
    In most cases, no, because the switch has something called fuses. The fuses tell the switch what OS version it should have, and if it has something different the switch won't turn on.

    EDIT: If we get CFW that ignores what the fuses say, then it's possible
     
    Johannee, notimp and Assasin1990 like this.
  4. John_Drek

    OP John_Drek Newbie
    Newcomer

    Joined:
    Apr 30, 2018
    Messages:
    9
    Country:
    United States
    Even when restoring the Nand it causes those fuses to burn?
     
  5. TerraPhantm

    TerraPhantm GBAtemp Fan
    Member

    Joined:
    Jul 27, 2007
    Messages:
    492
    Country:
    United States
    Efuses would prevent you from booting it directly, but you could probably boot into it using the RCM vulnerability (but that would also mean you'd need to do that everytime you boot the switch)
     
  6. ThisIsDaAccount

    ThisIsDaAccount GBAtemp Maniac
    Member

    Joined:
    Apr 8, 2016
    Messages:
    1,159
    Country:
    United States
    The fuses are already burnt and are separate from the nand. If you restore a nand backup, it won't restore fuses to the necessary state.
     
    John_Drek likes this.
  7. mikey420

    mikey420 GBAtemp Advanced Fan
    Member

    Joined:
    Dec 11, 2015
    Messages:
    911
    Country:
    United States
    You could theoretically use the bootrom hack to run any version of the system software you'd like but the best way to do so would not be by modifying the actual nand . your best bet would be an "emunand" with all the securities patched out by the loader. Though for the life of me I can not imagine it would be all that helpful to downgrade.
     
  8. Ronhero

    Ronhero Too Weird to Live, Too Rare to Die
    Member

    Joined:
    Jun 28, 2014
    Messages:
    3,464
    Country:
    United States
    Ive also wondered this myself. Lets say in theory you could dg to 1.0 and install a custom patch to bypass fuse check. Then lets say a software only full cold boot comes along (fingers crossed since I'm still on 1.0) it may in theory let you then boot into emunand.

    Just a theory but it would be nice
     
  9. TerraPhantm

    TerraPhantm GBAtemp Fan
    Member

    Joined:
    Jul 27, 2007
    Messages:
    492
    Country:
    United States
    If you have a patch to bypass the fuse check, then you already have a patch to cold boot into emunand.
     
    Quantumcat and hippy dave like this.
  10. EclipseSin

    EclipseSin Ignorant Wizard
    Member

    Joined:
    Apr 1, 2015
    Messages:
    2,063
    Country:
    United Kingdom
    There is no way to downgrade an updated switch. If the console is using an exploit to load old firmware, bypassing efuse checks, it is not a downgrade. Without the exploit it would be a brick.

    eFuses work just like any other fuse. If it's blown, it is blown, there is no software to reset it as it is an electronic short, not a bit or register.

    That said, there are a few use case scenarios, but those are few and becoming less.
     
  11. TheCyberQuake

    TheCyberQuake Certified Geek
    Member

    Joined:
    Dec 2, 2014
    Messages:
    5,011
    Country:
    United States
    No you can't.
    Modifying the NAND would cause it to fail signature checks.
    You can't resign it because we don't have the private keys (which are different from the public keys we currently have)
    You could patch signature checks, but at that point you have access to just running cfw anyway, meaning there would be no benefit to using it.
     
    Deathscreton and blinkzane like this.
  12. blinkzane

    blinkzane Panic at your moms house
    Member

    Joined:
    Jul 24, 2012
    Messages:
    943
    Country:
    United States
    There is a single line that disables fuse checks.
    Give it time
     
  13. Retr0id

    Retr0id Member
    Newcomer

    Joined:
    Apr 12, 2018
    Messages:
    33
    Country:
    United Kingdom
    Sure, you can ignore the fuses with CFW, but if you already have CFW then there's no point in downgrading...
     
    Draxzelex, Assasin1990 and leorod199 like this.
  14. TerraPhantm

    TerraPhantm GBAtemp Fan
    Member

    Joined:
    Jul 27, 2007
    Messages:
    492
    Country:
    United States
    Do you really think they would exclude that from the signature check?
     
  15. lonix

    lonix Member
    Newcomer

    Joined:
    Apr 28, 2018
    Messages:
    26
    Country:
    Australia
    It happened on Xbox 360 so I'm sure it could happen here.

    Give the Devs time to research the boot process.
     
  16. dubbz82

    dubbz82 GBAtemp Advanced Maniac
    Member

    Joined:
    Feb 2, 2014
    Messages:
    1,572
    Country:
    United States
    Given that they failed to properly implement RSA on multiple occasions? Eh, I wouldn't be too surprised.
     
  17. Draxzelex

    Draxzelex GBAtemp Legend
    Member

    Joined:
    Aug 6, 2017
    Messages:
    12,322
    Country:
    United States
    Louder for the people in the back
     
  18. lembi2001

    lembi2001 GBAtemp Fan
    Member

    Joined:
    Dec 29, 2015
    Messages:
    416
    Country:
    What would downgrading get you?

    There is no point in downgrading. A fully working Emunand or CFW with signature patches is the best case scenario.

    As has previously been stated the FW checks that the number of burnt efuses match the hardcoded figure in the firmware. If not a kernel panic and ensues and your switch is effectively dead.

    Efuses are impossible to revert back to their unburnt state once tripped. There would be no benefit from running a downgraded OS anyway as you lose the ability to play game that require a newer FW.

    Once Scires finishes Atmosphere we will see what benefits we get and where others can expand on the work.
     
  19. notimp

    notimp Well-Known Member
    Member

    Joined:
    Sep 18, 2007
    Messages:
    4,486
    Country:
    Laos
    Started from a modchip, or having to be tethered to another powered device on every boot. ;) Then getting banned from N being able to detect the modchip based on voltage fluctuations. ;) (The last part is not that likely - but still.. ;) )

    Of course you could run it in CFW if they are getting updated regularly. :) Just not online, for long. Probably. ;) (Depending on a couple of unknowns).
     
    Last edited by notimp, May 1, 2018
  20. WaterBotttle

    WaterBotttle GBAtemp Regular
    Member

    Joined:
    Dec 19, 2014
    Messages:
    163
    Country:
    I've seen this question pop up a few times and I also had the thought myself. However it won't work.

    The Switch has e-fuses, which act as a permanent counter in the processor.

    The Switch bootloader (The 2cd piece of code to run after the bootrom) checks the values of the e-fuses (http://switchbrew.org/index.php?title=Fuses#Anti-downgrade)

    If the value of the firmware is too low compared to the e-fuses because you've tried to downgrade then the bootloader will not continue any further.

    There is a way to downgrade but it's not very useful, see here.
     
Draft saved Draft deleted
Loading...

Hide similar threads Similar threads with keywords - downgrade, possible, firmware