Windows 11 24H2 goes from “unsupported” to “unbootable” on some older CPUs

[DuckDodgers]

Microsoft continues its battel to get rig of old unfashioned hardware for its latest Windows 11 release, this time with deeper changes.

 

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According to posts from a user named Bob Pony on X, formerly Twitter, the latest Windows 11 builds refuse to boot on older processors that don't support a relatively obscure instruction called "POPCNT." Short for "population count," it's used for "counting the number of bits in a machine word," according to an explainer by programmer Vaibhav Sagar.

 

It's unclear why POPCNT has become the load-bearing CPU instruction for a whole bunch of Windows components, but it looks like the Windows kernel, the system's USB and network drivers, and other core system files now require the instruction

 

In modern x86 CPUs, POPCNT is implemented as part of the SSE4 instruction set. For Intel's chips, it was added as part of SSE4.2 in the original first-generation Core architecture, codenamed Nehalem. In AMD's processors, it's included in SSE4a, first used in Phenom, Athlon, and Sempron CPUs based on the K10 architecture. These architectures date back to 2008 and 2007, respectively.

That effectively bars mid-2000s Intel Core 2 Duo systems and early Athlon 64-era PCs from booting Windows 11 at all, not that they officially supported it in the first place.

 

Well, you either have a PC with "new" CPU after 2008 so it doesn't matter or you don't care for Windows 11 anyway -- in both cases nothing changes for the adoption rates of this Windows generation.

 

Source:

https://arstechnica.com/gadgets/2024/02/windows-11-24h2-goes-from-unsupported-to-unbootable-on-some-older-pcs

[Techstorm970]

Unbothered, unbridled "meh" from me.

 

C2D machines are for putting Windows 7 and legacy software on, not latest-greatest stuff.  A C2D machine with Windows 11 better be a tinker-toy and nothing more.

[GuiltySpark_]

Big nothingburger. 

 

SSE4.2 is available way back to chips you really have no business putting 11 on anyway. 

 

 

[Electronics Wizardy]

So before this I think you needed the core 2 era chips(Pretty sure windows 10/11 64 bit won't run on a p4) or althon 64s(not sure never had any personally to test) So this gets rid of 2005 ish to 2008 ish hardware from running windows 11 unofficially. I don't see this as a big deal as those systems are pretty rare(In the USA at least where I am) and generally pretty slow for modern web browsing. If using this using these newer instructions makes windows development better or allows newer hardware to be used better I see this as a win overall.

 

I am more worried windows 10 has a pretty high marketshare, and whats gonna happen in Oct 2025 when support drops. Thats gonna leave a lot of un support win 10 system in the wild if something doesn't change.

[da na]

16 minutes ago, Electronics Wizardy said:

So before this I think you needed the core 2 era chips(Pretty sure windows 10/11 64 bit won't run on a p4) or althon 64s(not sure never had any personally to test) So this gets rid of 2005 ish to 2008 ish hardware from running windows 11 unofficially. I don't see this as a big deal as those systems are pretty rare(In the USA at least where I am) and generally pretty slow for modern web browsing. If using this using these newer instructions makes windows development better or allows newer hardware to be used better I see this as a win overall.

 

I am more worried windows 10 has a pretty high marketshare, and whats gonna happen in Oct 2025 when support drops. Thats gonna leave a lot of un support win 10 system in the wild if something doesn't change.

Windows 10 64-bit will run on on Pentium 4 HT and Pentium D chips, both of which are x64. Athlon 64s are x64 as the name suggests so Windows 10 x64 runs fine on those as well. 

However, neither very well. Core 2 Duo is my absolute minimum for any W10 usability.

[Electronics Wizardy]

2 minutes ago, da na said:

Windows 10 64-bit will run on on Pentium 4 HT and Pentium D chips, both of which are x64. Athlon 64s are x64 as the name suggests so Windows 10 x64 runs fine on those as well. 

However, neither very well. Core 2 Duo is my absolute minimum for any W10 usability.

I'll have to try again then. I remember Win 10 x64 not working on a P4, but win 7 x64 worked fine. Win 10 x32 worked fine on that system. I think it was a p4 630. Could be the specific generation of p4 as there was a couple generations.

[manikyath]

this is one of those things where this instruction has been there for a long ass time but not forever, there was a case where using it would optimize something, so the decision had to be made.

 

something very similar to this happened in windows 10 on some specific build as well, iirc it took some early P4 chips out the running.

[RejZoR]

30 minutes ago, Techstorm970 said:

Unbothered, unbridled "meh" from me.

 

C2D machines are for putting Windows 7 and legacy software on, not latest-greatest stuff.  A C2D machine with Windows 11 better be a tinker-toy and nothing more.

Didn't know a 4 core, 8 threads Ryzen 5 2500U is equivalent of that. Yet I can't install Windows 11 on it anymore for like 2 years now without hacking s**t up and I'm totally not in mode to deal with that nonsense anymore. Linux was a solution. It has its own idiocies, but at least I can install it any time I want without all these dumb hardware restrictions or having to deal with nonsense like mandatory online account.

[powertoys]

CPUs without these instructions are so old that their corresponding chipsets do not even have native Windows 10 drivers, let alone Windows 11 (even then, Windows Update will still download and install graphics drivers if you're running a Core 2 Duo in Windows 10 - I speak from experience).

[Lunar River]

 

anyone actually upset at 2008 cpus no longer being usable, you might want to recheck the calendar to see what year you're in

[RejZoR]

22 minutes ago, Lunar River said:

 

anyone actually upset at 2008 cpus no longer being usable, you might want to recheck the calendar to see what year you're in

Ryzen 5 2500U was released in 2017. I can't install Windows 11 on it for last 2 years or so. So, a 5 years old CPU is "too old". Especially since I'm still using it on Linux for all the browsing and multimedia and it does it all without a single hiccup. But it's totally too old yo!

[Lunar River]

12 minutes ago, RejZoR said:

Ryzen 5 2500U was released in 2017. I can't install Windows 11 on it for last 2 years or so. So, a 5 years old CPU is "too old". Especially since I'm still using it on Linux for all the browsing and multimedia and it does it all without a single hiccup. But it's totally too old yo!

That's nice, and not at all what this article is about.

 

[StDragon]

Microsoft is actively rewriting portions of the OS code with Rust for security reasons. As i understand it, POPCNT allows for efficient code to be compiled. So, it stands to reason why MS would raise the baseline by making this a hard requirement. It's about time frankly.

[jagdtigger]

Looks like quite a few frogs in this topic enjoy slowly getting boiled.......

[leadeater]

1 hour ago, RejZoR said:

Ryzen 5 2500U was released in 2017. I can't install Windows 11 on it for last 2 years or so. So, a 5 years old CPU is "too old". Especially since I'm still using it on Linux for all the browsing and multimedia and it does it all without a single hiccup. But it's totally too old yo!

If Rufus and a tick box is too difficult to do a fresh install then that is totally a you problem. Installing Windows 11 on a Ryzen 2500U is trivially easy.

 

[powertoys]

50 minutes ago, leadeater said:

Installing Windows 11 on a Ryzen 2500U is trivially easy.

You can install but you will have little to no Windows 11 drivers. Touchpad was behaving weird on one of the unsupported laptops I tested, and some games had extreme stuttering issues that did not happen at all under 10.

[StDragon]

1 hour ago, leadeater said:

If Rufus and a tick box is too difficult to do a fresh install then that is totally a you problem. Installing Windows 11 on a Ryzen 2500U is trivially easy.

People are still going to bitch when the Windows 11 24H2 feature update installs and fails to boot from a subsequent reboot.

"Just because you can, doesn't mean you should"

People need to stop setting themselves up for failure. Window 11 was never meant to be installed on those CPUs. The fact it could be done was a bonus.

[starsmine]

1 hour ago, leadeater said:

If Rufus and a tick box is too difficult to do a fresh install then that is totally a you problem. Installing Windows 11 on a Ryzen 2500U is trivially easy.

 

Yea it’s not that I couldn’t, it’s that it’s a laptop so I can’t just work around it. It had the TPM, hell zen+ is officially supported and tested. It’s all the boutique drivers that don’t get tested because they don’t have to and zen1 laptops were all done by a companies C team because no one trusted AMD yet. 
 

It wasn’t until zen2 that oems actually tried. 
 

desktop zen 1 are a non issue for the most part though 

[jagdtigger]

1 hour ago, leadeater said:

If Rufus and a tick box is too difficult to do a fresh install then that is totally a you problem.

Talking about missing the point. The limitation itself shouldnt exist in the 1st ace.....

[starsmine]

41 minutes ago, jagdtigger said:

Talking about missing the point. The limitation itself shouldnt exist in the 1st ace.....

yes, yes it should. There is no reason that MS needs to test that the OS works on PCs that it has zero intention to support as TPM is necessary to keep things sandboxed (and in the future Pluton)

NON-TPM boot is a failsafe fall back, not a safe running mode.

[StDragon]

54 minutes ago, jagdtigger said:

Talking about missing the point. The limitation itself shouldnt exist in the 1st ace.....

You can't install Windows 98 on newer CPUs without some interesting hacks and work-arounds.

Should both Intel and AMD update their design to support older software?

At some point, the disparity in age between software and hardware grows so far apart that compatibility can't be guaranteed to remain forever. 

[leadeater]

1 hour ago, jagdtigger said:

Talking about missing the point. The limitation itself shouldnt exist in the 1st ace.....

Actually it very much should exist, and it's also good that it is very easily without any great effort to get around it if you so wish. So those that want to and can (know how) have that option rather than not at all.

 

But at some point your old hardware isn't going to work with the "new thing" and you'll find exactly zero OS developers, even Linux, caring about releases and builds that aren't actually supported anymore.

 

2 hours ago, powertoys said:

You can install but you will have little to no Windows 11 drivers. Touchpad was behaving weird on one of the unsupported laptops I tested, and some games had extreme stuttering issues that did not happen at all under 10.

That is very much not a Zen+ or a Ryzen 2500U issue though.

 

But again your device with a Ryzen 2500U would have been fully supported by everyone involved for at least 5 years and last I checked those with the newest Zen+ based products will be in their 7th year of CPU release so hardly much to complain about. Keep using the device if you really want, it's not going to stop working. Consider getting something new if you care about security updates though.

[leadeater]

2 hours ago, StDragon said:

People are still going to bitch when the Windows 11 24H2 feature update installs and fails to boot from a subsequent reboot.

I would expect a compatibility check though, but certainly agree.

 

"We could have much faster or better experiences but we have to support SSE2 because [lame reason]" - thanks now we all suffer

 

The actual issue as it pertains to Windows is the rolling feature releases and security updates being dependent with those along with OS support being tied to that. It's actually entirely possible to be running the first build of Windows 10 and have to this year security updates if Microsoft went back to that Windows Update and OS support scheme. They don't want to because it's giant hassle and why they stopped doing it that way.

[aisle9]

*looks at his technically supported PCs all still running Windows 10 because f*ck Microsoft.

[StDragon]

52 minutes ago, leadeater said:

It's actually entirely possible to be running the first build of Windows 10 and have to this year security updates if Microsoft went back to that Windows Update and OS support scheme. They don't want to because it's giant hassle and why they stopped doing it that way.

Which is fine by me.

Starting with Windows 10 1903, you could "upgrade" by just applying Enablement Packages (basically cumulative updates that sets a reg flag to the newer build). With 1809, and prior, you have to install the Feature Update which amounted to an in-place OS update. Keeping enterprise clients up to date is no easy task unless you're rolling with LTSC.

Regardless, Microsoft's move to an annual feature cadence is a welcoming move.