[Info-vax] Webinar "AUTOGEN and SYSGEN"

[Paul Sture]

On Sun, 22 Apr 2012 03:25:09 -0700, Bart Zorn wrote:

> Reading through the PDF I stumbled upon the following on slide 8:
> 
> SYSBOOT gets an implicit USE CURRENT
> • Brings the current set into working memory
> • SET commands change working memory
> • CONTINUE command does an implicit WRITE CURRENT
> • Once booted, the ACTIVE set is materialized from the CURRENT set
> 
> I think something is wrong here. The first two bullets are OK. But the
> third one is, IMHO, not true. SYSBOOT does not do a WRITE CURRENT. It is
> SYS$STARTUP:VMS$INITIAL-050_VMS.COM (called by SYS$SYSTEM:STARTUP.COM)
> which does or does not do a SYSGEN WRITE CURRENT, depending on the value
> of the WRITESYSPARAMS parameter. The fourth bullet is also not correct.
> It should read something like "Once booted, the ACTIVE set is
> materialized from the working memory of SYSBOOT"
> 
> This can be easily verified by changing, in SYSBOOT, the value of some
> parameter and setting WRITESYSPARAMS to 0. Then issue the CONTINUE
> command and after VMS has started up, verify the value of that parameter
> with SYSGEN. The changed value of the parameter is NOT reflected in the
> CURRENT set. It IS reflected in the ACTIVE set, however. In other words,
> no WRITE CURRENT command (or equivalent action) has been executed,
> neither by SYSBOOT nor by VMS.

Yes.  Otherwise there would be no point in having WRITESYSPARAMS at all.

> Note that WRITESYSPARAMS has a special treatment by SYSBOOT. Initially
> it is set to 0. As soon as you change any other parameter's value,
> SYSBOOT set WRITESYSPARAMS to 1, Therefore, if you want to inhibit the
> WRITE CURRENT during startup, you have to set WRITESYSPARAMS to 0 just
> before you enter the CONTINUE command.

Correct:

SYSBOOT>  SET WRITESYSPARAMS 0

SYSBOOT>  SET BALSETCNT 160

SYSBOOT>  SHOW WRITESYSPARAMS
Parameter Name            Current    Default     Min.     Max.     Unit
--------------            -------    -------    -------  -------   ----
WRITESYSPARAMS                  1          1         0         1 Boolean



-- 
Paul Sture