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#21
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Far and near pointers on the 80286 and later
http://www.garlic.com/~lynn/2010g.html#9 Far and near pointers on the 80286 and later http://www.garlic.com/~lynn/2010g.html#15 Far and near pointers on the 80286 and later part of it was how to cut the development for reliability and security. we had been called in to consult with small client/server startup that wanted to do payment transactions on their server. they had some well designed and well tested application code that would handle the transactions. I then a bunch of stuff that I claimed was necessary to take a quality application and turn it into a "service" (aka business critical, 7x24) ... which took nearly ten times the original application effort. It included doing some compensating processes and diagnostic manual for Internet environments. At the same time there were various milspec security development stuff that were also being required for critical financial infrastructures .... stuff like 2167A ... which also took something like ten times the effort of what might be considered well-designed, well-implemented, well-tested application (and then re-applied for any enhancement/changes). Part of the JAD was could I take both the security & RAS stuff that was increasing standard application development by a factor of ten times .... and get it down to maybe only 2-3 times. misc. past posts mentioning business critical being 4-10 times standard development for business critical: http://www.garlic.com/~lynn/2001f.html#75 Test and Set (TS) vs Compare and Swap (CS) http://www.garlic.com/~lynn/2001n.html#91 Buffer overflow http://www.garlic.com/~lynn/2001n.html#93 Buffer overflow http://www.garlic.com/~lynn/2002n.html#11 Wanted: the SOUNDS of classic computing http://www.garlic.com/~lynn/2003g.html#62 IBM says AMD dead in 5yrs ... -- Microsoft Monopoly vs. IBM http://www.garlic.com/~lynn/2003j.html#15 A Dark Day http://www.garlic.com/~lynn/2003p.html#37 The BASIC Variations http://www.garlic.com/~lynn/2004b.html#8 Mars Rover Not Responding http://www.garlic.com/~lynn/2004b.html#48 Automating secure transactions http://www.garlic.com/~lynn/2004k.html#20 Vintage computers are better than modern crap ! http://www.garlic.com/~lynn/2004l.html#49 "Perfect" or "Provable" security both crypto and non-crypto? http://www.garlic.com/~lynn/2004p.html#23 Systems software versus applications software definitions http://www.garlic.com/~lynn/2004p.html#63 Systems software versus applications software definitions http://www.garlic.com/~lynn/2004p.html#64 Systems software versus applications software definitions http://www.garlic.com/~lynn/2005b.html#40 [Lit.] Buffer overruns http://www.garlic.com/~lynn/2005i.html#42 Development as Configuration http://www.garlic.com/~lynn/2005n.html#26 Data communications over telegraph circuits http://www.garlic.com/~lynn/2006n.html#20 The System/360 Model 20 Wasn't As Bad As All That http://www.garlic.com/~lynn/2007f.html#37 Is computer history taught now? http://www.garlic.com/~lynn/2007g.html#51 IBM to the PCM market(the sky is falling!!!the sky is falling!!) http://www.garlic.com/~lynn/2007h.html#78 John W. Backus, 82, Fortran developer, dies http://www.garlic.com/~lynn/2007n.html#10 The top 10 dead (or dying) computer skills http://www.garlic.com/~lynn/2007n.html#76 PSI MIPS http://www.garlic.com/~lynn/2007n.html#77 PSI MIPS http://www.garlic.com/~lynn/2007o.html#23 Outsourcing loosing steam? http://www.garlic.com/~lynn/2007p.html#54 Industry Standard Time To Analyze A Line Of Code http://www.garlic.com/~lynn/2007v.html#53 folklore indeed http://www.garlic.com/~lynn/2008e.html#41 IBM announced z10 ..why so fast...any problem on z 9 http://www.garlic.com/~lynn/2008e.html#50 fraying infrastructure http://www.garlic.com/~lynn/2008e.html#53 Why Is Less Than 99.9% Uptime Acceptable? http://www.garlic.com/~lynn/2008i.html#33 Mainframe Project management http://www.garlic.com/~lynn/2008n.html#20 Michigan industry http://www.garlic.com/~lynn/2008n.html#35 Builders V. Breakers http://www.garlic.com/~lynn/2008p.html#48 How much knowledge should a software architect have regarding software security? http://www.garlic.com/~lynn/2009.html#0 Is SUN going to become x86'ed ?? -- 42yrs virtualization experience (since Jan68), online at home since Mar1970 |
#22
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Far and near pointers on the 80286 and later
Anne & Lynn Wheeler writes:
At the same time there were various milspec security development stuff that were also being required for critical financial infrastructures ... stuff like 2167A ... which also took something like ten times the effort of what might be considered well-designed, well-implemented, well-tested application (and then re-applied for any enhancement/changes). http://www.garlic.com/~lynn/2010g.html#9 Far and near pointers on the 80286 and later http://www.garlic.com/~lynn/2010g.html#15 Far and near pointers on the 80286 and later http://www.garlic.com/~lynn/2010g.html#16 Far and near pointers on the 80286 and later wasn't a member ... but did get invited to some of their meetings ... somewhat favorite of mine from their website ... courtesy of the wayback machine: http://web.archive.org/web/200010181.../frampapr.html -- 42yrs virtualization experience (since Jan68), online at home since Mar1970 |
#23
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Far and near pointers on the 80286 and later
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#24
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Far and near pointers on the 80286 and later
George Neuner wrote:
On Sun, 28 Mar 2010 08:16:02 -0500, jmfbahciv jmfbahciv@aol wrote: George Neuner wrote: Leaving aside why anyone would _want_ to bring back Multics ... To study how to make an OS secure from the beginning project plan to the last edit for shipping? Ok, but there are other secure systems to study such as Amoeba and EROS. They are more modern than Multics, and in particular, were designed to be distributed. I don't mind anyone studying Multic - there is plenty to learn from it (including what not to do) ... but I would be against trying to revive it as a working operating system. One of the things which separated MULTICS from most other operating systems was the way in which rings were used. Many operating systems use (or mostly use) only two rings, similarly to the "master mode" and "slave mode" of 1960's computers. By putting things like libraries and privileged linked programs (terminology escapes me, it's been ~40 years) in rings, access could be more nuanced. |
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Far and near pointers on the 80286 and later
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#27
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Far and near pointers on the 80286 and later
Peter Flass wrote:
Tim McCaffrey wrote: In article , says... George Neuner wrote: On Sun, 28 Mar 2010 08:16:02 -0500, jmfbahciv jmfbahciv@aol wrote: George Neuner wrote: Leaving aside why anyone would _want_ to bring back Multics ... To study how to make an OS secure from the beginning project plan to the last edit for shipping? Ok, but there are other secure systems to study such as Amoeba and EROS. They are more modern than Multics, and in particular, were designed to be distributed. I don't mind anyone studying Multic - there is plenty to learn from it (including what not to do) ... but I would be against trying to revive it as a working operating system. One of the things which separated MULTICS from most other operating systems was the way in which rings were used. Many operating systems use (or mostly use) only two rings, similarly to the "master mode" and "slave mode" of 1960's computers. By putting things like libraries and privileged linked programs (terminology escapes me, it's been ~40 years) in rings, access could be more nuanced. Well, the CDC Cyber 180 series (and NOS/VE) did something similar. OS/2 uses three: one for the kernel, one for drivers, etc., and the third for user programs. Yes, that's a much more MULTICS model, allowing drivers and system support to run at "more than user" to access devices, raw memory, etc. |
#28
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Far and near pointers on the 80286 and later
Bill Davidsen writes: One of the things which separated MULTICS from most other operating systems was the way in which rings were used. Many operating systems use (or mostly use) only two rings, similarly to the "master mode" and "slave mode" of 1960's computers. By putting things like libraries and privileged linked programs (terminology escapes me, it's been ~40 years) in rings, access could be more nuanced. 370xa started out with access registers and then added program call (& return). issue was that favorite son batch operating system heritage (from real memory environment) was extensively pointer-passing API. In the initial transition to virtual memory (OS/VS2 SVS) it was just a single large virtual memory (pointer-passing APIs still working). In the migration to MVS ... each application was given its own address space ... but an image of the MVS kernel appeared in (8mbyte) half of each (16mbyte) virtual address space (pointer passing API easily worked since MVS kernel code as in the same address space of each application). The problem was that there were a lot of "subsystems" (semi-privileged operations) that had resided outside the kernel (called by applications with pointer passing API) that were now in their own virtual address space (i.e. application would generate system call and the kernel would invoke the subsystem in its own virtual address space). To continue with pointer-passing API, a "common segment" was created that also resided in each virtual address space. This started out was 1mbyte of each virtual address space ... but grew ... somewhat proportional to the number of independent subsystems and the number of concurrent executing applications. eventually in the timeframe of of large 3033s ... common segments were threatening to exceed five mbytes (growing to six ... leaving only 2mbytes for applications in each application virtual address space). to start to address the problem ... a subset of 370xa access registers were introduced in 3033 called dual-address space mode. Application wold make kernel call to invoke subsystem, kernel would swap the home & alternate virtual address space pointers before invoking the subsystem. each instance of subsystem execution would have alternate address space pointer to its invoking application ... and could directly address the invoking applications virtual address space. Now 370xa introduced introduced access registers with more generalized implemenation of dual-address space as well as 31bit virtual addressing (31bit virtual addressing would have alleviated the common segment attempting to completely take-over remaining application area in each virtual address space). program call (& return) ... application instruction that references a kernel hardware table ... that defines available "subsystems" and the rules for changing around the address space pointers. now applications can directly invoke a subsystem in different address space, w/o the overhead of kernel call processing (much like a library routine call that resides in the same address space). description of program call http://publibz.boulder.ibm.com/cgi-b...20040504121320 program return http://publibz.boulder.ibm.com/cgi-b...20040504121320 discussion of access registers ("current instruction space and a maximum of 15 other spaces) http://publibz.boulder.ibm.com/cgi-b...20040504121320 discussion of address spaces http://publibz.boulder.ibm.com/cgi-b...20040504121320 recent posts mentionin dual-address space &/or access registers: http://www.garlic.com/~lynn/2010c.html#41 Happy DEC-10 Day http://www.garlic.com/~lynn/2010d.html#81 LPARs: More or Less? http://www.garlic.com/~lynn/2010e.html#75 LPARs: More or Less? http://www.garlic.com/~lynn/2010e.html#76 LPARs: More or Less? -- 42yrs virtualization experience (since Jan68), online at home since Mar1970 |
#29
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Far and near pointers on the 80286 and later
In article ,
Bill Davidsen wrote: Peter Flass wrote: OS/2 uses three: one for the kernel, one for drivers, etc., and the third for user programs. Yes, that's a much more MULTICS model, allowing drivers and system support to run at "more than user" to access devices, raw memory, etc. Typical operating system centricity :-( A massive gain in RAS could be obtained by allow multiple 'rings' of protection at the application level. It would enable reliable run-time systems, debuggers and run-time diagnostics, and increase the number of bugs that were actually located rather than simply being hacked around until they now longer showed up. This would make an INCREDIBLE difference to the RAS of parallel support and the hairy asynchronous 'libraries', such as windowing systems. At present, it's infeasible even to report bugs in most of those, because they aren't repeatable and can't be proved not to be user errors. But, if the component were in a protected environment, a dump showing that privilege level would be clear evidence of a bug. Yes, that would mean the vendors of such things improving their standards, but at present they have no incentive to .... Regards, Nick Maclaren. |
#30
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Far and near pointers on the 80286 and later
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