From: kludge@panix.com   
      
   Lawrence =?iso-8859-13?q?D=FFOliveiro?=   wrote:   
   >On Wed, 24 Dec 2025 15:44:02 -0500 (EST), Scott Dorsey wrote:   
   >   
   >> On Wed, 24 Dec 2025 19:02:02 -0000 (UTC), Lawrence D’Oliveiro wrote:   
   >>>   
   >>> What exactly does Plan9 get you?   
   >>   
   >> The ability to have as much stuff as possible running outside the   
   >> kernel ring. The more stuff you can kick out of the kernel, the less   
   >> stuff there is which can cause catastrophic failure when things go   
   >> wrong.   
   >   
   >Ah, the hoary old microkernel refrain. You'd think, after something   
   >like four decades of repeating the same tired old claims without being   
   >able to back them up, the microkernel fans would have given up by now.   
      
   How so?  The microkernel does exactly what it's claimed to do, and it's a   
   very commonly used architecture.   
      
   It's usually not a good idea on the x86 because message-passing performance   
   between user-space programs becomes very poor because of the x86   
   memory protection limitatations.   
      
   You do see lot of microkernels in embedded systems today, on architectures   
   more friendly to user-space sharing.  And of course most of the hupervisors   
   in use for virtualization today are microkernels since the user space   
   limitations aren't such a big deal there.   
      
   >> OSX started out adapting some of the Plan9 philosophy but it mostly   
   >> turned into bloat and the current OSX kernel looks nothing like a   
   >> classic microkernel.   
   >   
   >Gee, I wonder why they succumbed to real-world evidence in that way ...   
      
   There's still a microkernel at the bottom of OSX, but really the XNU kernel   
   mostly just runs BSD under itself.  OSX does use mach message passing still,   
   but I think the end result is both contrary to the microkernel philosophy   
   and generally contrary to good design practices.  It's just another case   
   of feeping creaturism rather than a deliberate move in any direction.   
   --scott   
      
      
      
   --   
   "C'est un Nagra. C'est suisse, et tres, tres precis."   
      
   --- SoupGate-Win32 v1.05   
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