On Sun, Jun 30 2024, Eli Zaretskii wrote:
>> You don't do anything useful other than packing up the arguments that
>> the signal handler receives and put them in the queue.
>
> What arguments are those?  SIGCHLD doesn't tell us the PID of the
> process (or any other data that could be used to identify the
> process), AFAICT.  What if two or more sub-processes exited while we
> are in MPS-land?

This patch below implements the idea I was thinking about.

>> The MPS documentation says quite clearly that a scanner must not access
>> MPS-managed memory other than the block it receives as argument:
>
> What do you mean by "scanner"?  I was talking about our signal
> handlers.  If they qualify as "scanner", please explain why.

I mean dflt_scan.

> Anyway, if a signal handler cannot do anything useful, the only
> alternative is to block select signals around code which could violate
> those restrictions.

We will see.