[cyphar]

That's not really a fair statement. First of all, Linux started as Linus just reimplementing the Unix semantics, so edge cases and subtle semantics should be expected to be different. Secondly, most Unix-based OSes are barely compatible in their facilities.

Sure, you have DTrace (which only macOS, illumos and FreeBSD have) and ZFS (which only illumos and FreeBSD have) but the rest is similarly incompatible. Solairs/illumos even has a complete NIH-reimplementation of FreeBSD's kqueue (event ports). They have different views on containerisation (Zones/Jails). They've historically had very different opinions on /proc and ioctls, not to mention that they were developed separately for such a long time that their shared history is not very recent.

As a result, porting from Solaris to FreeBSD is also difficult. Maybe it's harder or easier than porting to GNU/Linux, but I wouldn't just flat-out claim that GNU/Linux is the only member doing things that are incompatible.

[X86BSD]

Sun's event ports are so similar to kqueue cantrill has said they should have just adopted kqueue.

And there are not different views on zones and jails. They are the same thing. Sun just took the idea of jails and flushed them out further adding a separate network stack for each zone, which jails now also have. But they operate on the same principle and ideas. Jails was bare bones at inception. Jails shared their IP stack with the host, this was before cloud computing and the need for separate network stacks. They both started with being secure and then adding features where the Linux container mess started with features and then continues to try and address the fact they are insecure by design. So jail and zones are similar.

Porting from FreeBSD to Solaris and vice Versa is easier than you think. If it was insanely hard FreeBSD wouldn't have zfs or Dtrace from Sun. Dtrace was almost single handedly ported by one engineer. An amazing engineer, but he Was the only one. Same with ZFS. And illumos ported the FreeBSD installer. Also done by one individual. All very good engineers but still just one.

[cyphar]

I also have watched Cantrill's talks. But I think you're intentionally ignoring my point, in two ways:

* You were discussing porting a Linux application, not a kernel feature like DTrace, ZFS, Zones, kqueue, etc. Obviously porting a kernel feature between two OSes that share a kernel history is going to be easier than porting to an entirely different kernel. It's almost tautological. Porting an application has more to do with whether the syscall/libc interfaces are compatible and if you take kqueue/eventports as an example you still need to do standard porting work. glibc provides BSD-like interfaces so it's not like you have to switch away from bzero or whatever -- that's not the hard part of porting code.

* You specifically stated that Linux is "off in the weeds", "doing their own poor re-implementations of tech others have already done". Ignoring how disrespectful that is, your response to me saying "the whole Unix family re-implements each others ideas all the time -- DTrace and ZFS are the exception and only three members of the family use them" isn't helping your original point.

Also this whole section is just a non-sequitur:

> And there are not different views on zones and jails. They are the same thing. [Long description of how they are different and were developed separately.] [Random aside about Linux containers and how they're a mess.] So jail and zones are similar.

I am aware of the similarities and differences between Jails and Zones, and I'm also very painfully familiar with Linux containers. Not sure why you're bringing them up in a discussion about porting applications between different Unix-like operating systems. Sounds like you just have an axe to grind.

[binarycrusader]

event ports is not an NIH reimplementation. It was a framework intentionally developed to meet specific business and technical needs within the Solaris threading model at that time.

It's far closer to Windows IOCP than FreeBSD kqueues IMHO.

It's also been one of the most successful features added to Solaris and is used throughout the system.