Memory Tagging Extension for M5 MacBooks

That link provides some intersting reading.

As of the date of the Apple Memory Enforcement architecture artcile on Sept 9, 2025, the A19 was released. The M5, said to be a variant of the A19, followed about a month later. To date the M5 has only appeard in (plain), not yet in PRO or MAX versions.

The code base for MacOS is clearly a variant of the code base for iOS. Given the scope of this implementation, it seems extremely likely that Apple Memory Enforcement architecture will be common in MacOS for supported processors as soon a possible.

Readers here are other users like you. Anyone with accurate insider information is already under non-disclosure agreement, and simply can't say.

I suggest you keep watching the Trade Press for more information.

Servant of Cats wrote:

Re: “The code base for MacOS is clearly a variant of the code base for iOS.”

More the other way around, since Mac OS X predates the iPhone.

Actually macOS is becoming more like iOS than the other way around. For a simplistic easy to see item, macOS 13.x Ventura acquired the long existing iOS System Settings for better or worse.

@etresoft who is a respected forum contributor & developer has mentioned multiple times on this forum how the macOS codebase has been incorporating various iOS subsystems & features over the years.

For information on this and related topics, see the recent presentation by Ivan Krstić of Apple:

• https://www.youtube.com/watch?v=Du8BbJg2Pj4

More info:

• https://www.usenix.org/system/files/login/articles/login_summer19_03_serebryany.pdf
• https://www.schneier.com/blog/archives/2025/09/apples-new-memory-integrity-enforcement.html
• https://developer.arm.com/documentation/109697/0100/Feature-descriptions/The-Armv8-9-architecture-extension?lang=en#md454-the-armv89-architecture-extension__FEAT_MTE4

I don’t have the MacBook Pro (14-inch, 2025) handy to run the command that purportedly checks for this (mentioned over at HN, and reposted here):

  $ sysctl -a | grep MTE4
  hw.optional.arm.FEAT_MTE4: 1

That the M5 processor might the MTE4 feature also doesn’t mean that macOS is currently using it, and — at least here in the Apple forums — we’re not in a position to speculate on when or if that might happen.

Re: “The code base for MacOS is clearly a variant of the code base for iOS.”

More the other way around, since Mac OS X predates the iPhone.

How about:

"ARM versions of MacOS and iOS are both based on essentially the same code base."