[Info-vax] Android development Was Re: OT: Larry Ellison takes retirement as CEO of Oracle

[David Froble]

JF Mezei wrote:
> On 14-09-23 09:43, John Reagan wrote:
> 
>> For such things, you write user-mode system services.  
> 
> 
> OK then. When your application does a call or a branch to and address
> that resides in  systerm service or user written system service, what
> causes the OS to re-evaluate what privileges become authorized (and/or
> enabled) and what causes them to once again be re-evaluated when code
> returns to the caller ?
> 
> When C compiler compiles my code, does it know that calling SYS$QIO
> requires the addition of special "call" (trap or whatever) instruction
> that it doesn't add when calling a service in another shareable image ?
> 
> Are system services (and user written ones) not just a different flavour
> of a shareable image from the compiler and linker's and perhaps image
> actiuvator's points of view ?

I'll first declare that I don't know, or forgot, the answer to your 
question.

But, perhaps a guess.  Why does the OS care what priv bits you have set? 
  I can't see any reason.  Now, when some operation requires some priv 
bit(s), then that bit (or mask) can be checked.  Until then, who cares?