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Conference vaxaxp::vmsnotes

Title:VAX and Alpha VMS
Notice:This is a new VMSnotes, please read note 2.1
Moderator:VAXAXP::BERNARDO
Created:Wed Jan 22 1997
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:703
Total number of notes:3722

302.0. "Any way to modify the SID register?" by NYOSS1::ZAMORA (Edgar - DTN 352-2486) Mon Mar 10 1997 17:15

    
    I have a customer who wants to know if the SID (as in F$GETSYI("SID"))
    is modifiable, say through a kernel mode program.  The reason he gave
    me as to why he wants to modify this value is that they have an ancient
    VAX application that checks the SID.  When they tried to move it to a
    newer VAX it, of course, refused to run.  And of course they do not
    have sources or a newer version etc.  So they figure the best they
    can do is try to hack the SID of the newer VAX to match the old one.
    
    Any information regarding this would be much appreciated.
T.RTitleUserPersonal
Name		DateLines
302.1Beware Software License(s)XDELTA::HOFFMANSteve, OpenVMS EngineeringMon Mar 10 1997 17:2421
  If the application is checking the SID, it's probably some sort of
  licensed software, and we should not be assisting this customer in
  relocating this software without more information on the status of
  the package and the customer's license.

  (If the vendor is out of business with no organization currently
  supporting the package and/or the customer has the license rights
  to do it, it is likely easier to disable the SID check via PATCH.)

  The SID register is etched directly into the silicon on all VAX
  microprocessors, and is not thus alterable without a new version
  of the chip...

  Some VAX platforms do have a way for the console to "spoof" the
  contents the SID.  (The VAX 6000 series, if memory serves.)

  Some VAX platforms have a settable "serial number" via either
  backplane switches or firmware, allowing a portion of the SID to
  be reset.  (The VAX-11/7xx series comes to mind.)
302.2Can't change the SID.....STAR::CROLLWed Mar 12 1997 09:3010
To the best of my knowledge, the SID value cannot be changed; it's in the
silicon.

There is a register called the XSID, which lives in NVRAM on some systems (not
on all) and contains things like the distinction between server and workstation
and a few other things.  This is alterable, but it would be extremely difficult
to do, especially in a customer environment.  It's be easier to hack
F$GETSYI('SID') to return the spoof'd value!

John