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Comment by dragonsenseiguy | Hacker News Reader

Sidenote but: it's crazy how big this update is. 13 GB is crazy

Update from 26.3 to 26.4 for the Studio Display XDR was 2.4GB. And that's for a variant of iOS designed for screens.

Yeah I’m honestly not sure why macOS updates seem to be so huge. Often gigabytes. Do they actually have thousands of changes, so they basically ship out new versions of almost all system libraries? Or is it that they don’t have good diffing in place? Or is it a BSD thing where you basically ship everyone at once since it’s all sort of “one version” of the base system?

> Yeah I’m honestly not sure why macOS updates seem to be so huge.

An update to macOS 26.5 contains all the necessary code to update a Mac from 26.0 to 26.5 for both x86_64 and arm64 architectures.

Is that an over the air update? Lol.

But aren't they able to do incremental builds and separated x64/arm64?

They know which OS version is requesting an update, at least the version number part.

> But aren't they able to do incremental builds and separated x64/arm64?

During the PowerPC to Intel transition, they did stuff like that; perhaps at their current scale, there's reasons why they don't.

Supporting both architectures enables a macOS install to boot an Intel Mac or an Apple Silicon Mac, which is useful in a dual-architecture environment.

It's easy to check for dual architecture support; just use the file command:

    $ file /bin/ls
    /bin/ls: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64e:Mach-O 64-bit executable arm64e]
    /bin/ls (for architecture x86_64): Mach-O 64-bit executable x86_64
    /bin/ls (for architecture arm64e): Mach-O 64-bit executable arm64e

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