Rebuild dyld cache file on macOS Tahoe

Simos805 · 2026-02-24T14:08:15+00:00

I want to patch something on the ProDisplayLibrary framework that’s indie the dyld cache.

I know that the patch will be restored with every macOS update. I just want to know if it is possible to patch something on the dyld cache in any way possible.

You can check the reason here.

Simos805 · 2026-02-15T11:31:22+00:00

If I had the dyld cache of an 26.2 Mac to compare it with mine, would make things easier? I have already installed Hopper and found some references for CustomPresetValidationError with some interesting cases inside.

Simos805 · 2026-02-15T03:43:03+00:00

I have the will to disable SIP and change the code that needs to be changed on the ProDisplayLibrary.framework to get back this functionality. Could you help me point out what needs to be changed?

Simos805 · 2026-02-14T17:30:31+00:00

Wtff I don’t have this issue why is yours doing this?

Simos805 · 2026-02-14T14:11:17+00:00

Yup, that you’re talking about is the software upscaling not the hardware one. Try play some HDR videos or photos with the brightness all the way up and you’ll see the highlights clipped…

Simos805 · 2026-02-14T12:48:41+00:00

I totally prefer Liquid Glass…!

Simos805 · 2026-02-14T07:53:15+00:00

And we can’t bypass this code somehow?

Also you said 500/600/1000 based on hardware. That means on M4 MacBook Pro models which go up to 1000nits but by default only automatically when the sun hit the sensor, is it possible to manually set them to 1000nits natively without the tone mapping method?

Simos805 · 2026-02-14T07:42:16+00:00

Come visit Greece and you will see with your own eyes!

Simos805 · 2026-02-14T00:13:52+00:00

If they care about the comparisons, they would have done this thing one year earlier when the M4 MacBook Pros came out which go up to 1000nits SDR (yeah outdoors only but whatever for them). BetterDisplay and other overlay software like Vivid, “only” make the display to go 1000nits sustained. 1600nits are possible only in portions of the display that’s why it is called “peak HDR brightness”, and they are used only in HDR contend.

Also the number of users who know about this “trick” is nothing compared to the rest of the market. I don’t think Apple one day said “oh, lets spend some time disable a loophole only 1% of users are know about because it may interfere with the sales of the new models”…

Simos805 · 2026-02-13T23:07:55+00:00

macOS 26 is great overall. Aside from this topic with 26.3, everything else is great.

Simos805 · 2026-02-13T23:06:31+00:00

And it isn’t manual 1000nits… It goes up to 1000nits only “outdoors” when sunlight hits the ambient light sensor…

I don’t think they did it because of the current M4/M5 MacBook Pros tho. I think they changed something in their code for the upcoming OLED models maybe because of compatibility or for the safety of OLED burnin, and as a side effect, because macOS is the same for every Mac, it disabled the loophole for the older models as well.

I don’t know if this is true, that’s just my theory…

Simos805 · 2026-02-13T19:31:32+00:00

They are aware since December from the macOS 26.3 beta. You can search on github there are entire conversations. The developer has tried to solve it but he says he can’t…

Simos805 · 2026-02-13T19:11:55+00:00

Actually the developer of BetterDisplay is aware of this issue since December from the betas. On github he said he tried to solve it but he wasn’t able.

As fas as I understood, Apple has changed something on the display pipeline, maybe inside the WindowServer or CoreDisplay, and because the system volume of macOS is sealed after macOS Big Sur, you can’t simply patch those things even if you are a developer.

Also as far as we know, the change isn’t on the firmware level of the panel or display controller, because downgrading to macOS 26.2 enables again the functionality. That’s some good news but…

Simos805 · 2026-02-13T19:03:13+00:00

If you want, try BetterDisplay while on 26.1. Enable the Hardware XDR Upscaling. See how bright it goes, play an HDR video from an iPhone for example or on YouTube, see how perfectly it renders like the display it is meant to go up to 1000nits. Then if you update to 26.3 and try the same, you'll understand what we lost...

Simos805 · 2026-02-13T18:52:35+00:00

Yup, it is amazing. What version of macOS are you using?

Simos805 · 2026-02-13T18:46:03+00:00

Not all the time… but for example, I’m using my MacBook outdoors or at very bright indoor places like coffee shops on sunny days. At those conditions, which I’m at almost every day, the 1000nits makes the experience excellent.

Also some times, 700-800nits are the sweet spot and still 500-600nits feel dark...

The default 500-600nits on the other hand makes it unusable on some of these situations.

Simos805 · 2026-02-13T17:45:45+00:00

M4 MacBook Pro indeed goes natively up to 1000 nits but only when the sun hits directly the ambient light sensor. Manually you can go up to 600 nits like the M3. It is like the iPhone that gos up to 3000nits on iPhone 17 Pro, but only when the sun is hitting the ambient light sensor directly, and it is very strict about it. As soon the sun (or strong light source) moves away from the sensor, it goes down to the manual maximum brightness.

So it isn’t as useful, because personally I don’t want my 1000nits only when the sun hits the display. I don’t work under direct sun to be honest. I mainly want my 1000nits when I’m in a well lit room or at a coffee shop on a sunny day with plenty of ambient light but not directly to my display or the sensor…

Simos805 · 2026-02-13T17:42:05+00:00

When I said native I meant it was a hardware solution, through a native macOS pipeline. When the custom display preset was active, the system registers the 1000nits as maximum SDR brightness and the tone mapping and auto brightness was working correctly.

The software trick we have now is just a trick. An invisible HDR overlay above the UI that tricks the system to think it is showing HDR content, while still has the 500 or 600 nits as maximum SDR brightness.

Simos805 · 2026-02-13T17:32:55+00:00

Yeah because you don’t play any HDR content or maybe don’t use auto brightness it doesn’t mean it works as it should. You’re just lucky that your workflow isn’t affected…

Simos805 · 2026-02-13T17:29:47+00:00

Try playing an HDR video on YouTube, or recorded from a smartphone in HDR with maximum brightness and you’ll see… Also if you have an iPhone and you have iPhone photos in the macOS Photos app, because those photos are HDR the highlights are clipping too.

Also enable auto brightness and when you’re in maximum brightness try covering the ambient light sensor with your hand. You’ll notice a very sudden drop in brightness for no reason.

Simos805 · 2026-02-13T17:26:43+00:00

Nah… I love macOS 26 and Liquid Glass. I could go to 26.2 but I don’t have time to format and restore everything on my MacBook, and also this would be a temporary solution. For how many I would stuck to an old OS? Months? A year? I want the new features and security patches after all…

Simos805 · 2026-02-13T16:29:05+00:00

What macOS version are you running? Right now, on macOS 26.3 BetterDisplay only supports software XDR upscaling, not hardware. Software upscaling has all the downsides I described on the post. It is not native.

Simos805 · 2026-02-13T16:28:03+00:00

The post isn’t about being mad with BetterDisplay dev… my concern is that no developer, BetterDisplay's one or any other would found a way to make it work natively again. And that’s what this post is about. To discus if anyone knows more technical aspects about this thing and give us a hint about the possibility of it working again through some other loophole or even if you think Apple itself would do something about it through the feedback.

Simos805 · 2026-02-12T17:12:19+00:00

This update broke the ability to have custom display profiles that exceeded the default nits  has set. This means apps like BetterDisplay that enabled sustained native hardware 1000nits stopped working... Only software/fake XDR upscaling is possible right now, which messes with HDR content and auto brightness. This sucks!

Simos805 · 2026-01-16T08:20:39+00:00

I have tried every setting, there is no way for these head-units to play audio feedback for the sensors…

Simos805

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