[Info-vax] How much of VMS is still in MACRO-32?

[hb]

On 6/1/21 5:17 PM, John Reagan wrote:
> On Tuesday, June 1, 2021 at 10:39:53 AM UTC-4, Camiel Vanderhoeven wrote:
>> Op dinsdag 1 juni 2021 om 14:11:16 UTC+2 schreef xyzz... at gmail.com:
>>> When I read Simon's question about "self-modifying code", I took that as code that modifies itself 
>>> during program execution. It turned into "generating code on the fly". That's a different question. 
>>> I know of a few places that generate code on the fly but nothing in OS itself.
>> I do :-) 
>>
>> When execlets are loaded, the transfer vectors to call system services are generated on the fly.
> I wasn't going to mention that "symbol vectors" on x86 are trampolines much like the VAX-era
> transfer vectors.  I consider this just a relocation that the image activator/exec-loader performs.
> 
> On Linux systems, you might even see PLT routines also self-modify by doing a dlopen/dlsym in
> their first execution, modify themselves to just jump to the target on subsequenct executions.
> We don't do that.
> 

FWIW, the loaded code, generated by the linker, is different from what
the loader writes: it is more than changing a (target) address.