40 years of Unix (BBC) [LWN.net]

40 years of Unix (BBC)

Posted Aug 21, 2009 3:51 UTC (Fri) by pabs (subscriber, #43278)
In reply to: 40 years of Unix (BBC) by jordanb
Parent article: 40 years of Unix (BBC)

Which features are missing from Unix that Multics had?

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40 years of Unix (BBC)

Posted Aug 21, 2009 4:25 UTC (Fri) by jordanb (guest, #45668) [Link] (5 responses)

Off the top of my head, single level storage, and RPC through dynamic linking. They also had things that are just now getting added to modern Unicies in a very incomplete fashion, like MAC and ACLs,

40 years of Unix (BBC)

Posted Aug 21, 2009 23:13 UTC (Fri) by Wol (subscriber, #4433) [Link] (4 responses)

Don't know to what extent it was hardware, and what software, but Pr1mos (a multics derrivative too) had fast ring-level switching. Essentially, a kernel call with context switch and ring jump was just as fast as a user-level subroutine call. But it was much more secure (look at the recent stuff over jumping to a null pointer - that entire class of problems just can't happen.

Cheers,
Wol

40 years of Unix (BBC)

Posted Aug 25, 2009 2:59 UTC (Tue) by pabs (subscriber, #43278) [Link] (3 responses)

Is anyone working on any of the above features for Linux?

40 years of Unix (BBC)

Posted Aug 25, 2009 21:51 UTC (Tue) by jordanb (guest, #45668) [Link] (2 responses)

Well, MAC and ACLs are getting implemented, slowly, with things like SELinux.

Single-level storage would require fundamental changes in Unix such that it wouldn't be Unix anymore, although this feature does live on in IBM mainframe products (the 'i' and 'z' series, I believe).

Memory-mapped IPC would be possible, I'd think, if processes were able to mmap eachother's executable space and have a linker that could do the binding to the exposed functions on the fly. I don't see why that couldn't be done in a backwards-compatible manner. I also don't know of anyone trying to do it.

40 years of Unix (BBC)

Posted Aug 27, 2009 22:47 UTC (Thu) by giraffedata (guest, #1954) [Link] (1 responses)

Single-level storage would require fundamental changes in Unix such that it wouldn't be Unix anymore, although this feature does live on in IBM mainframe products (the 'i' and 'z' series, I believe).

System I (called Eserver I series from 2001 to 2005, and a bunch of other things before that) does, but the System Z operating systems are about as far as you can get from it.

"mainframe" isn't a very meaningful word these days, but to most people it simply means IBM System Z. Nobody uses the word for System I.

40 years of Unix (BBC)

Posted Aug 28, 2009 2:59 UTC (Fri) by jordanb (guest, #45668) [Link]

Thanks for correction.

I said that because I had read an article by an IBM shill about SLS in IBM products. They *were* speaking specifically about the I-series but kept making statements about how "IBM mainframe users just expect this sort of feature" so I assumed it was more widespread. :<