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

[JF Mezei]

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 ?