How bad is 20.0.0+ firmware's consequence of "14MB from the applet pool, down from 40MB"?

R4ismychildhood · Nov 17, 2025

I have been hesitating to update for a long time since Atmopshère wrote:

https://github.com/Atmosphere-NX/Atmosphere/releases

Please note: As a result of changes made to nintendo's software in 20.0.0, there is roughly 10MB less memory available for custom system modules.
- We can only steal a maximum of 14MB from the applet pool, down from 40MB.
- To compensate for this, ams.mitm's heap usage has been reduced by 20MB.
  - To facilitate this, a new helper module (memlet) was added, so that memory may be temporarily stolen during the romfs building process.
  - Hopefully, this results in relatively little breakage, however it is possible that user mods which replace extremely large numbers of files in The Legend of Zelda: Tears of the Kingdom may no longer function.
    - If you are affected by this, you will see "Data abort (0x101)" when trying to launch the game with mods.
    - Please reach out to sciresm on discord if this occurs to share your error report binary. However, some issues may be impossible to fix.
    - I apologize sincerely if the issue is impossible to resolve, but I have been forced unavoidably to make compromises here, and I think this is the best balance to be struck.

So, 19.0.1 will be the latest possible firmware without less memory available for custom system modules? I want to be on the latest but "optimal" (in this context, applet RAM) firmware...

Thanks!

P.S. Still on <19.0.0

Blythe93 · Nov 18, 2025

R4ismychildhood said:
So, 19.0.1 will be the latest possible firmware without less memory available for custom system modules? I want to be on the latest but "optimal" (in this context, applet RAM) firmware...

That's pretty much it. 18.1.0 has 40MB, 19.x.x 24MB and 20.x.x 14MB. Being on 19.x.x isn't as severe as being on 20.x.x and newer. Apparently, you can use SAK tool or similar to downgrade the firmware requirement for some games but it might not work all the time.

Since I'm not using many modules nor anything really crazy, I haven't noticed any issues being on 20.x.x compared to the 18.1.0 or 19.0.1. Game tiles are a bit slower to load up but that's about it. 21.x.x broke most of the homebrew apps but once they are updated I'm sure they'll be fine as well.

R4ismychildhood · Nov 19, 2025

Blythe93 said:
That's pretty much it. 18.1.0 has 40MB, 19.x.x 24MB and 20.x.x 14MB. Being on 19.x.x isn't as severe as being on 20.x.x and newer. Apparently, you can use SAK tool or similar to downgrade the firmware requirement for some games but it might not work all the time.

Since I'm not using many modules nor anything really crazy, I haven't noticed any issues being on 20.x.x compared to the 18.1.0 or 19.0.1. Game tiles are a bit slower to load up but that's about it. 21.x.x broke most of the homebrew apps but once they are updated I'm sure they'll be fine as well.

Thank you so much!

Post automatically merged: Nov 19, 2025

Blythe93 said:
That's pretty much it. 18.1.0 has 40MB, 19.x.x 24MB and 20.x.x 14MB. Being on 19.x.x isn't as severe as being on 20.x.x and newer. Apparently, you can use SAK tool or similar to downgrade the firmware requirement for some games but it might not work all the time.

Since I'm not using many modules nor anything really crazy, I haven't noticed any issues being on 20.x.x compared to the 18.1.0 or 19.0.1. Game tiles are a bit slower to load up but that's about it. 21.x.x broke most of the homebrew apps but once they are updated I'm sure they'll be fine as well.

Sorry, where's the part that says 19.x.x has only 24MB from the applet pool? Really want to ensure what I'm getting myself into before updating, thanks!

Blythe93 · Nov 19, 2025

R4ismychildhood said:
Sorry, where's the part that says 19.x.x has only 24MB from the applet pool? Really want to ensure what I'm getting myself into before updating, thanks!

I've asked it sometime in the past, here's bth's reply to that. 21.x.x now has less than 4MB of available memory. :/

R4ismychildhood · Nov 20, 2025

Blythe93 said:
I've asked it sometime in the past, here's bth's reply to that. 21.x.x now has less than 4MB of available memory. :/

~~Thank you so much! If that's the case then I'll update to 18.1.0 & consider that as the last "memory not compromised version"...~~

Post automatically merged: Nov 20, 2025

Blythe93 said:
I've asked it sometime in the past, here's bth's reply to that. 21.x.x now has less than 4MB of available memory. :/

sorry I just want to see the actual log by SciresM, I still can't find where it says for 19.x.x it's just 24MB...

Blythe93 · Nov 20, 2025

R4ismychildhood said:
sorry I just want to see the actual log by SciresM, I still can't find where it says for 19.x.x it's just 24MB...

I haven't found it either but instead took bth's word for granted. He worked on maintaining sys-patch at the very least so I take it that he knows his stuff.

Reploid · Nov 20, 2025

ok, so we stay on 20 forever, hopefully will never be forced to go to 21+

nitrozz · Nov 20, 2025

that's why i still on 19.0.1

XenoFredo · Nov 20, 2025

I see almost no difference having been on 20.x for a while now, as someone else has said, only the tiles for the games load like half a second slower when you show all games.

Otherwise everything works fine, but I'm only using Ultrahand as sysmodule, mods like CTGP Deluxe work fine too even though they sometimes crash on startup (very rarely though), but it's possible it was doing that on the older firmwares.

I see no reason not to update to 20.x at this point. For 21.x I'm going to wait a bit that all the apps are officially updated and every possible bug has been discovered and fixed.

Blythe93 · Nov 20, 2025

Indeed. Being on 18.x.x and 19.x.x only matters to those that have lots of mods and active sys-modules. If you're not one of them, being on 20.x.x (and soon, 21.x.x) shouldn't be much of an issue.

Space_Goddess_Samus_Aran · Nov 20, 2025

shit have to downgrade my emummc to 19.x from 20.5.0, but have to resetup all shit again xD

duckbill007 · Nov 20, 2025

Also it matters to those who use game mods for games with large number of files in romfs. KOTOR2 for example. Of course you can repack those games with mod even on switch but it is not handy.

Lamcza · Nov 20, 2025

Blythe93 said:
That's pretty much it. 18.1.0 has 40MB, 19.x.x 24MB and 20.x.x 14MB. Being on 19.x.x isn't as severe as being on 20.x.x and newer. Apparently, you can use SAK tool or similar to downgrade the firmware requirement for some games but it might not work all the time.

Since I'm not using many modules nor anything really crazy, I haven't noticed any issues being on 20.x.x compared to the 18.1.0 or 19.0.1. Game tiles are a bit slower to load up but that's about it. 21.x.x broke most of the homebrew apps but once they are updated I'm sure they'll be fine as well.

~~Did you try that downgrading, or perhaps can you link me to the right places of how to ?~~

ok nevermind

thx dude it works even on latest ******** games

Earthshine · Nov 22, 2025

Blythe93 said:
I've asked it sometime in the past, here's bth's reply to that. 21.x.x now has less than 4MB of available memory. :/

So no one has incorrect information, per SciresM 21.x.x has 16MB.

Hacking Post in thread 'Atmosphere-NX - Custom Firmware in development by SciresM'

Nov 19, 2025

impeeza said:
3.86 for be exact

What? My testing showed 16 MB available for custom sysmodules at runtime.

Blythe93 · Nov 22, 2025

Earthshine said:
So no one has incorrect information, per SciresM 21.x.x has 16MB.

Seems like it.

Nynrah · Mar 17, 2026

I'm on FW 20.x.x at the moment and haven't really noticed anything besides longer loadtimes for the tiles when showing all games. Until reading others say the same here I never realized it was related to this, to be honest.

I generally don't use many modules or mods, though. I use Breeze for cheats and in the past I've used emuiibo with tesla overlay (that was on 19.x.x, though, so I don't know how that performs now). Having gathered newer versions of the homebrew programs I use for fw 21.x.x, I'm intending to update my fw and atmosphere in the nearby future because some of my games and updates need 21.x.x and I don't want to tarnish my files by modifying them.

I do hope this trend of removing all the available RAM doesn't continue, though...

davimassini · Mar 17, 2026

This is way worse than I thought it would be. This reduction in the memory pool almost killed my project of creating an achievement system for the Switch. Right now, I can only run my module alone (whereas before I could keep sys-ftpd, Fizeau, and other modules running alongside it). I'm still trying to figure out how to optimize my code even more.

Hopefully, this gets rolled back or at least doesn't get any smaller.

Nynrah · Mar 17, 2026

Can someone confirm if fw 21.x.x can still run Breeze and emuiibo via tesla overlay?
How much worse do the game tile loading get compared to FW 20.x.x?

paulkelly30 · Mar 17, 2026

Some homebrew has been updated to run on fw 21.x.x but some games like hogwarts and Witcher are more unplayable due to the memory taken over, stay where you are.

Nynrah · Mar 17, 2026

paulkelly30 said:
Some homebrew has been updated to run on fw 21.x.x but some games like hogwarts and Witcher are more unplayable due to the memory taken over, stay where you are.

How do you mean their memory is taken over? Games themselves should be unaffected as long as you're not using mods or too many sysmodules?

How bad is 20.0.0+ firmware's consequence of "14MB from the applet pool, down from 40MB"?

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Hacking Post in thread 'Atmosphere-NX - Custom Firmware in development by SciresM'

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