Subject: Re: new sysctl(KERN_PROC, ...) interface (was: sysinfo(2))
To: Simon Burge <simonb@NetBSD.ORG>
From: Darren Reed <>
List: tech-kern
Date: 04/18/2000 09:14:49
In some email I received from Simon Burge, sie wrote:
> > >  2) Need a way to get the address of the ps_strings struct for a given
> > >     process - this can vary per process on a machine running both 32 and
> > >     64 bit processes.
> > > 
> > >     Possible solutions: add
> > >         
> > >         sysctl(CTL_KERN, KERN_PROC_PSADDR, pid, &va);
> > > 
> > >     or keep address of ps_strings in struct proc and pass back inside
> > >     struct kinfo_proc2.
> > 
> > This is bad.  As much as others may detest it, I'd go for putting this
> > information in a static sized buffer.  If people do "ps axwww" or "ps e"
> > then it should fall back, as required, to a method which supports the
> > return of architecture dependant sized structures.
> Any way of getting the address of ps_strings is bad?  Do you mean keep
> {argv,environ} in a fixed sized buffer?  If so, this would make 1) above
> moot...

Not keep, but copy out to when doing the sysctl() (or is that what you
mean here ?) - ie do what ps does with ps_strings for it, upto a limit
of course.

Re. displaying wait channel, etc, hmmm....I think you have to bite the
bullet and force them to always be 32bit or always be 64bit for the
purposes of this new sysctl.

The other thing which may bite is changes to field width when formatting
for 32/64bit when showing pointers.