[Info-vax] VSI: "Official 8.4-1H1 Launch"

[David Froble]

Stephen Hoffman wrote:
> On 2015-06-08 15:07:44 +0000, John Reagan said:
> 
>> On Monday, June 8, 2015 at 10:51:28 AM UTC-4, Bill Gunshannon wrote:
>>
>>> This may come off as a really stupid question, but isn't VMS a 
>>> monolithic kernel?  In which case VM and everything else is available 
>>> as soon as the secondary (or tertiary) boot loader loads the kernel 
>>> into memory and jumps there.  Right?
>>
>> Has not been a monolith since VMS V3 or so.
> 
> FWIW...  When viewed at the file level, OpenVMS is not a monolithic 
> kernel.   But in strict computing architecture terms, OpenVMS is a 
> monolithic kernel.   VAX/VMS V5.0 brought the modular executive, which 
> means that OpenVMS is a monolithic kernel design with loadable modules. 
> (Unfortunately without much support for unloading kernel code, but I 
> digress.)  Once OpenVMS is booted, the kernel is one big wad of code, 
> which is made slightly more tenable through the use of three privileged 
> processor modes.   Hybrid and modular kernels tend to use user-space 
> processes, with the closest OpenVMS analog being ACPs.   In short, 
> there's no general IPC communications layer used within the OpenVMS 
> kernel, and most OpenVMS kernel stuff is not implemented as ACP-like 
> constructs or UWSS-like constructs.  So... OpenVMS is monolithic, with 
> loadable bits.
> 
> Prior to V5.0, there were parts of the kernel environment that were 
> loaded during the bootstrap, or at run-time.  These included device 
> drivers.
> 
> For those that are curious, the Internals and Data Structures books all 
> have details of the bootstrap and system initialization.
> 
> Now as for what Bill was asking, OpenVMS initialization involves rather 
> more than loading one whacking great system file.
> 
> 

For sure.  For example, even after the VM code is in place, what's it 
going to work with?  I don't know the details, but I'd think there has 
got to be tables and such built / initialized so the code knows what 
memory it has to play with.  Probably lots of things that need some 
initialization.  The OS is code AND data, not just code.