Everhart, Glenn
From:	Paul A. Jacobi [jacobi@star.enet.dec.nospam.com]
Sent:	Wednesday, February 17, 1999 5:09 PM
To:	Info-VAX@Mvb.Saic.Com
Subject:	Re: NT minidrivers under VMS (was: OpenVMS on Intel?)


Chris Scheers wrote:
> 
> 
> Has anyone looked at supporting the various Alpha/NT mini drivers under
> VMS?
> 

One difficult problem to solve is that NT device driver contain a
DriverEntry() routine which could not easily be ported to the current 
OpenVMS driver model.  

The NT DriverEntry() routine executes at IPL 0 in system thread
context.  
This routine has access to all system services such as the NT registry 
and the file system.  

The functionality provide by the NT DriverEntry() routine must be done 
in OpenVMS as a separate "Server" process, which would communicate with 
the OpenVMS device driver.

It my be possible to change the OpenVMS driver module to include NT
DriverEntry() functionality, but that would require major change to the
I/O kernel modules, possibly making existing drivers incompatible.  It 
would be hard to justify all of this risk against the value of porting
NT device drives.


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