[Info-vax] DECnet Phase IV broken after VSI update

[Lawrence D’Oliveiro]

On Thursday, November 4, 2021 at 1:19:18 PM UTC+13, Arne Vajhøj wrote:
>
> On 11/3/2021 7:55 PM, Lawrence D’Oliveiro wrote: 
>>
>> I’ve been having a look at this 
>> <https://vmssoftware.com/docs/VSI_IO_REF.pdf>. Seems this is a little 
>> bit different from a regular kernel driver: you need to use special 
>> PTD$xxx calls to open and close instances. Note this in the 
>> description of PTD$CREATE: “This channel is only intended to be used 
>> for PTD$XXX operations.” So there is some kind of extra layer on top 
>> of the kernel driver, and you are not supposed to access the latter 
>> directly.
>>
> Yes. 
> 
> PTD$ user mode library ---> some VMS kernel code ---> driver code 

And note the implication that bad things could happen if you $DASSGN the channel without calling PTD$DELETE. Or if you tried to $QIO yourself without using PTD$READ/WRITE.

I wonder why it was necessary to do it this way?