[Info-vax] Creating an open source version of VMS, was: Re: OpenVMS Hobbyist Notification

[Robert A. Brooks]

On 3/10/2020 8:35 PM, Dave Froble wrote:
> On 3/10/2020 6:43 PM, Michael Moroney wrote:
>> Dave Froble <davef at tsoft-inc.com> writes:
>>
>>> I haven't studied it from this particular perspective, and without doing
>>> so would only be guessing.  But I have to ask, why do you state this.
>>> As far as I know the VMS DLM has not much to do with the "kernel" of
>>> VMS, supposing there is a definition of that entity.
>>
>>> Remember, the VMS DLM does no enforcing.  It is strictly a utility that
>>> can maintain a database of locks and cooperating processes can be guided
>>> by the utility.
>>
>> The DLM is all kernel mode code and is intertwined with the cluster logic to
>> ensure it is consistent across the cluster.  Plus parts of the kernel itself
>> use it, as does the file system.
>>
> 
> Interesting.  Want to ask.  Is that implementation specific?  Just seems to me 
> that what it does could be done outside the kernel.  Of course, that gets into 
> defining just what is the kernel, right?
> 
> Does it need to be in the kernel because it's called from things in the kernel?
> 
> Or, is it in the kernel to allow system level locks without requiring SYSLCK priv?
> 
> By "file system" are you referring to RMS, or lower level stuff?

The file system is how ODS-2/ODS-5 are implemented via the eXtended Qio 
Processor (XQP).

-- 
                  -- Rob