cvs commit: src/etc/etc.mips ttys

[John Baldwin]

On Monday 05 May 2008 10:08:23 am M. Warner Losh wrote:
> In message: <200805050949.27063.jhb at freebsd.org>
>             John Baldwin <jhb at FreeBSD.org> writes:
> : On Monday 05 May 2008 04:07:22 am Poul-Henning Kamp wrote:
> : > In message <481EB19B.3000201 at freebsd.org>, Colin Percival writes:
> : > >Poul-Henning Kamp wrote:
> : > >> In message <200805050535.m455ZmI1030493 at repoman.freebsd.org>, Warner
> : > >> Losh write
> : > >>
> : > >> s:
> : > >>>  Added files:
> : > >>>    etc/etc.mips         ttys
> : > >>>  Log:
> : > >>>  Mips ttys file.  Copied from i386 version with removal of the vga
> : > >>>  entries.
> : > >>
> : > >> We should really replace this file with a script that generates it
> : > >> from a set of sensible parameters at build-time.
> : > >
> : > >Yes please -- kmacy might have worked around this, but at one point 
this
> : > >was the only non-kernel file which needed to be different for Xen 
builds.
> : >
> : > And for anyone looking at this, there is also a task to eliminate the
> : > pty devices in this file, the reason why they are there has to do with
> : > the introduction of the really weird notion of "remote logins" back in
> : > the early 1980'ies, we really could do better.
> : 
> : Err, I thought it was because utmp still uses the line index in /etc/ttys 
so 
> : ptys have to be listed in /etc/ttys to get an index.  I haven't looked at 
> : utmpx, but it might be nice if we had a utmp format that 1) didn't limit 
> : usernames to 16 chars, and 2) stored the name of the tty rather than a 
dev_t.  
> : 2) is what I think has broken 'w -M /var/crash/vmcore.X' since 5.x.
> 
> /var/run/utmp stores the name.  However, it does appear to use the
> index in /etc/ttys to write the record into /var/run/utmp.  typical
> entries look like:

Hmm, 'w' still uses the dev_t to match entries in utmp to processes.  Oh, w(1) 
uses stat() on the node in /dev so it always gets "live" dev_t's instead of 
reading them out of the core dump somehow, so that is how it breaks for core 
dumps.

-- 
John Baldwin