Re: Need help from a VAX abi expert (was: Reproducable kernel crash)

On Sat, Jan 11, 2025 at 05:20:42PM +0100, Anders Magnusson wrote:
> Anyway; adding the settings of the page registers to cpu_lwp_fork() is
> non-trivial (if the goal is just to remove the pmap_activate() call).

No, that part should not happen there, only the initialiization of the PCB
list. The registers will be set by another pmap_activate() call later in
the sequence before that lwp first time makes it to userland.

But again I am not claiming to fully understand what is going on and I
am seriously confused by some parts of the code - I will add instrumentation
and try to debug it further, now that you explained why this is needed here.

> > Side note:
> > what I don't undstand is why VAX needs a list of PCBs in its struct pmap.
> > Doesn't this always map 1:1 to the list pcbs of all lwp's in the process?
> > This list handling seems to be different to all other pmaps I have seen.
> Do you mean the list in PCB; pcb_pmnext?  IIRC it had to do with the logic
> for handling the page table resource map (since all lwp:s in a process share
> the same page table but have different PCBs).

Ok, I will read more code and ask questions...

Martin