It would probably rely on NVIDIA diver support as well so it’s not something that can just be fixed with a bios update from a third party vendor.

Everyone seems to be chasing this for some grand old awesomeness.... but the actual specifics of how many things have to be updated in order for it to all work is beyond laughable.
 
I wish it would all get worked out & be great  sooner than later , but I'm not counting on it.
 
A) cpu has to be the right ones....
B) the motherboard chipset then needs to be BIOS'd  properly with it...
C) the videocard needs a new Vbios allowing it to operate/ function...
D) & the videocard driver also needs to have it put in ...
....and then if all that happens , the game has to support it also .
 
 
Here is the list of games so far ;
 

GeForce RTX 30 Series Resizable BAR Supported Games
As of February 25th, 2021
Assassin's Creed Valhalla
Battlefield V
Borderlands 3
Forza Horizon 4
Gears 5
Metro Exodus
Red Dead Redemption 2
Watch Dogs: Legion

 
.and here is my favorite quote right from Nvidia - 
 
..

Much like AMD’s Smart Access Memory, Resizable BAR on Nvidia GPUs can boost frame rates in certain games by up to 10 percent. The boost is really game dependent, and resolution can also impact how much performance will increase. “In our testing, we’ve found some titles benefit from a few percent, up to 10 percent,” says Nvidia. “However, there are also titles that see a decrease in performance

A) Yes people are aware..
B) Updating your bios is an issue?
C) This is what i'm asking for in regard to 20-series, and only needs to be done once with this gen of cards
D) They already confirmed driver support and are taking the whitelist approach rather than just having it enabled all the time, meaning games that have performance regression will not have re-bar enabled. It's a new feature so no surprise only a few games support it / benefit from it.
 
I never alluded to a "gpu being worthless without it", but in the same light no one is going to upgrade to the 30-series because of it either. It just would have been a nice to have for the vast majority of gamers who undoubtedly still gaming on 10-series / 20-series today and for the foreseeable future the way things are going. 
 

lilballard
If they are planning to add resizable BAR to older gen like rtx 20 and/or older then i'll be much appreciated as it's going to be extra feature for older gen which wasn't offer at that time.

I wouldn't hold my breath. I don't know why some of you are getting so wound up over this. It's not going to magically make some unplayable game playable or give you a noticeable increase at all. If you are already at the limits of your GPU rendering capability, this isn't going to remedy that or breathe new life into your card. If your hypothetical GPU is already working as hard as it can, it doesn't really matter if it has faster or more efficient access to memory because it won't do anything to increase performance if the GPU can't process what it already has fast enough. For example if your card is struggling at 4K and getting 30fps in XXX game, enabling resizeable BAR isn't going to push that to 60 or even 40fps. It's just not going to matter. Even if we take best case scenario and it does get a 10% performance bump that's 3 frames per second. You, nor any other human being is going to be able to perceive the difference between a 30 or 33fps average in performance. That's also not to mention the very real possibility of negative scaling and it actually reducing your performance in some titles. 
 
All these posts of "customer appreciation" as a way for Nvidia to show support to people who feel like they are obligated to do so make me laugh. The real and hard truth is that it just isn't going to matter even if they did waste time and money to develop support for it. 

From what I have seen so far there is a fps boost in some games. But 1% lows are also relatively worse in a lot of those boosting scenarios. Therefore, if Vsync or any other kind of FPS management is being done it may not matter much as you are restricting the fps in those situations. I think it is mostly a marketing ploy by AMD to start. That being said, results for workstation type of apps seem to be the largest benefit as any app that loves access to more memory looks to benefit. Gaming not as much. I am no expert. I am just saying. :)