5 ms·

IOKit was actually built from the ground up for OS X! NeXT had a different driver model called DriverKit. I've never coded against either, but my understanding

by spijdar 6mo ago

IOKit was actually built from the ground up for OS X! NeXT had a different driver model called DriverKit. I've never coded against either, but my understanding was they're pretty different beasts. (I could be wrong) That said, indeed, the abstraction layer here is delightful! I know that some NetBSD devs managed to get PPC Darwin running under a Mach/IOKit compatibility layer back in the day, up to running Xquartz on NetBSD! With NetBSD translating IOKit calls. :-)

erichocean 6mo ago
As I remember it, they were basically the same—but IOKit is C++ (with restrictions) because 3rd party developers didn't want to learn Objective-C. But that's a hazy, 20 year old memory.
- steve1977 6mo ago
  From here: https://news.ycombinator.com/item?id=10006411 https://news.ycombinator.com/item?id=10006411 "At some stage in the future we may be able to move IOKit over to a good programming language"
  - xenadu02 6mo ago
    IOKit was almost done in Java; C++ was the engineering plan to stop that from happening. Remember: there was a short window of time where everyone thought Java was the future and Java support was featured heavily in some of the early OS X announcements. Also DriverKit's Objective-C model was not the same as userspace. As I recall the compiler resolved all message sends at compile time. It was much less dynamic.
    - pjmlp 6mo ago
      Mostly because they thought Objective-C wasn't going to land well with the Object Pascal / C++ communities, given those were the languages on Mac OS previously. To note that Android Things did indeed use Java for writing drivers, and on Android since Project Treble, and the new userspace driver model since Android 8, that drivers are a mix of C++, Rust and some Java, all talking via Android IPC with the kernel.
      - lukeh 6mo ago
        There was also the Java-like syntax for ObjC but I don’t think that ever shipped.
    - lemoncucumber 6mo ago
      > there was a short window of time where everyone thought Java was the future Makes me think of how plists in macOS are xml because back then xml was the future
- spijdar 6mo ago
  Yes, you're right! I'm just dolt who's never checked what a .kext on OS X actually is. I had been under the impression that DriverKit drivers were quite a different beast, but they're really not. Here's the layout of a NS ".config" bundle: ./CG6FrameBuffer.config/English.lproj ./CG6FrameBuffer.config/English.lproj/Info.rtf ./CG6FrameBuffer.config/English.lproj/Localizable.strings ./CG6FrameBuffer.config/CG6FrameBuffer_reloc ./CG6FrameBuffer.config/Default.table ./CG6FrameBuffer.config/Display.modes ./CG6FrameBuffer.config/CG6FrameBuffer The driver itself is a Mach-O MH_OBJECT image, flagged with MH_NOUNDEFS. (except for the _reloc images, which are MH_PRELOAD. No clue how these two files relate/interact!) Now, on OS X: ./AirPortAtheros40.kext/Contents ./AirPortAtheros40.kext/Contents/_CodeSignature ./AirPortAtheros40.kext/Contents/_CodeSignature/CodeResources ./AirPortAtheros40.kext/Contents/MacOS ./AirPortAtheros40.kext/Contents/MacOS/AirPortAtheros40 ./AirPortAtheros40.kext/Contents/Info.plist ./AirPortAtheros40.kext/Contents/version.plist OS X added a dedicated image type (MH_KEXT_BUNDLE) and they cleaned up a bit, standardized on plists instead of the "INI-esque" .table files, but yeah, basically the same.
  - KerrAvon 6mo ago
    You're focusing on the executable format, which is very much not the driver model.
- pjmlp 6mo ago
  Yes, also the same reason why Java was originally introduced, Apple was afraid that the developer community educated in Object Pascal / C++, wasn't keen into learning Objective-C. When those fears proved not true, and devs were actually welcoming Objective-C, it was when they dropped Java and the whole Java/Objective-C runtime interop.
steve1977 6mo ago
Funnily enough, there is a (different) DriverKit in macOS again now ;)
twoodfin 6mo ago
There’s a great video of a NeXT-era Steve Jobs keynote floating around—I think the one where he announces the x86 port as NeXT was transitioning to a software-only company—where he specifically calls out DriverKit and how great it is. Steve was not a developer but he made it his business to care about what they cared about.
- nxobject 6mo ago
  Yeah - even from the start, I remember NeXT marketing was spending a disproportionate amount of their time selling NeXT’s “object technology”, AppKit and Interface Builder, DPS as an advanced graphics model. It was good hunch from Steve, given how how modern NeXTSTEP feels in retrospect. For some reason, though, it means that people overlook how NeXT’s hardware was _very_ far from fast. You weren’t going to get SGI level oomph from m68k and MO disks.
  - lukeh 6mo ago
    Yup, even with a hard drive the m68k turbo slab was no speed demon. Wasn't too bad on HPPA though.
pjmlp 6mo ago
Driver Kit used Objective-C, and ironically it is back, as Apple gave the same name to the userspace driver model replacement for IO Kit.
- jen20 6mo ago
  > ironically it is back, as Apple gave the same name to the.... This isn't that ironic - reusing old names where the trademarks are already owned etc is a pretty common thing.

by spijdar 6mo ago

erichocean 6mo ago

As I remember it, they were basically the same—but IOKit is C++ (with restrictions) because 3rd party developers didn't want to learn Objective-C. But that's a hazy, 20 year old memory.

steve1977 6mo ago
From here: https://news.ycombinator.com/item?id=10006411 https://news.ycombinator.com/item?id=10006411 "At some stage in the future we may be able to move IOKit over to a good programming language"
- xenadu02 6mo ago
  IOKit was almost done in Java; C++ was the engineering plan to stop that from happening. Remember: there was a short window of time where everyone thought Java was the future and Java support was featured heavily in some of the early OS X announcements. Also DriverKit's Objective-C model was not the same as userspace. As I recall the compiler resolved all message sends at compile time. It was much less dynamic.
  - pjmlp 6mo ago
    Mostly because they thought Objective-C wasn't going to land well with the Object Pascal / C++ communities, given those were the languages on Mac OS previously. To note that Android Things did indeed use Java for writing drivers, and on Android since Project Treble, and the new userspace driver model since Android 8, that drivers are a mix of C++, Rust and some Java, all talking via Android IPC with the kernel.
    - lukeh 6mo ago
      There was also the Java-like syntax for ObjC but I don’t think that ever shipped.
  - lemoncucumber 6mo ago
    > there was a short window of time where everyone thought Java was the future Makes me think of how plists in macOS are xml because back then xml was the future
spijdar 6mo ago
Yes, you're right! I'm just dolt who's never checked what a .kext on OS X actually is. I had been under the impression that DriverKit drivers were quite a different beast, but they're really not. Here's the layout of a NS ".config" bundle: ./CG6FrameBuffer.config/English.lproj ./CG6FrameBuffer.config/English.lproj/Info.rtf ./CG6FrameBuffer.config/English.lproj/Localizable.strings ./CG6FrameBuffer.config/CG6FrameBuffer_reloc ./CG6FrameBuffer.config/Default.table ./CG6FrameBuffer.config/Display.modes ./CG6FrameBuffer.config/CG6FrameBuffer The driver itself is a Mach-O MH_OBJECT image, flagged with MH_NOUNDEFS. (except for the _reloc images, which are MH_PRELOAD. No clue how these two files relate/interact!) Now, on OS X: ./AirPortAtheros40.kext/Contents ./AirPortAtheros40.kext/Contents/_CodeSignature ./AirPortAtheros40.kext/Contents/_CodeSignature/CodeResources ./AirPortAtheros40.kext/Contents/MacOS ./AirPortAtheros40.kext/Contents/MacOS/AirPortAtheros40 ./AirPortAtheros40.kext/Contents/Info.plist ./AirPortAtheros40.kext/Contents/version.plist OS X added a dedicated image type (MH_KEXT_BUNDLE) and they cleaned up a bit, standardized on plists instead of the "INI-esque" .table files, but yeah, basically the same.
- KerrAvon 6mo ago
  You're focusing on the executable format, which is very much not the driver model.
pjmlp 6mo ago
Yes, also the same reason why Java was originally introduced, Apple was afraid that the developer community educated in Object Pascal / C++, wasn't keen into learning Objective-C. When those fears proved not true, and devs were actually welcoming Objective-C, it was when they dropped Java and the whole Java/Objective-C runtime interop.

steve1977 6mo ago

Funnily enough, there is a (different) DriverKit in macOS again now ;)

twoodfin 6mo ago

There’s a great video of a NeXT-era Steve Jobs keynote floating around—I think the one where he announces the x86 port as NeXT was transitioning to a software-only company—where he specifically calls out DriverKit and how great it is. Steve was not a developer but he made it his business to care about what they cared about.

nxobject 6mo ago
Yeah - even from the start, I remember NeXT marketing was spending a disproportionate amount of their time selling NeXT’s “object technology”, AppKit and Interface Builder, DPS as an advanced graphics model. It was good hunch from Steve, given how how modern NeXTSTEP feels in retrospect. For some reason, though, it means that people overlook how NeXT’s hardware was _very_ far from fast. You weren’t going to get SGI level oomph from m68k and MO disks.
- lukeh 6mo ago
  Yup, even with a hard drive the m68k turbo slab was no speed demon. Wasn't too bad on HPPA though.

pjmlp 6mo ago

Driver Kit used Objective-C, and ironically it is back, as Apple gave the same name to the userspace driver model replacement for IO Kit.

jen20 6mo ago
> ironically it is back, as Apple gave the same name to the.... This isn't that ironic - reusing old names where the trademarks are already owned etc is a pretty common thing.