[Info-vax] Baremetal emulators, was: Re: Alpha emulator for OSX

[Chris Scheers]

Stephen Hoffman wrote:
> On 2016-02-10 01:53:46 +0000, Chris Scheers said:
> 
>> It's not necessary for a "near bare metal" OS beneath an emulation to 
>> even have a stack to maintain.  There are many advantages to not 
>> having one.
>>
>> Done correctly, the underlying OS is just used as a hardware 
>> abstraction layer.  It does not need a network stack.  It just needs a 
>> way, e.g., PCAP, to allow the emulation access to the network card.  
>> Then all packets on the wire actually go to/from the emulation and 
>> never touch the underlying OS.
> 
> It'd be unusual to not expose at least a management and monitoring 
> interface and some sort of a software maintenance and upgrade path into 
> the emulator layer, and you're going to have to expose a console path 
> for anything of practical use; unless you're going to restrict the guest 
> to the serial ports or what the guest can manage.   Then there's that 
> the emulator marketeers are not going to like competing with serial 
> lines against an emulator that is network-managed and 
> network-upgradable.  Could somebody do a completely isolated emulator?  
> Sure.   Their own marketing would kill them, just as soon as some other 
> emulator broke from that model.


I do a lot of work with Data General emulation.

A good number of these are isolated machines and are NOT networked, 
either for the host or the emulated machines.  (Sometimes we need to get 
waivers from the security department for this.)

Essentially, these run as PLCs in a test/control environment.  It is not 
unusual to have serial cables and one or two terminals.  The clients do 
not want to hook up anything new to them.  They just want them to work 
the way they have for the last 30+ years.  (And in some cases, 
networking causes enough variability to prevent the machine from doing 
its job.)

Of course, this is not always true.  I'm seeing a need to network the 
emulated machine in about 25% of the installs.

The host is networked probably 60-70% of the time.  In this case, full 
updates, anti-virus, firewall, etc. is recommended for the host.

The other cases have no networking.  Quite often these machines have 
serious physical security.

PS: When networking of the emulated machine is used, it can be quite 
amusing (terrifying?) to see a PC (sometimes a laptop in testing) 
servicing hundreds of users.

-- 
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Chris Scheers, Applied Synergy, Inc.

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