[TUHS] kernel boots kernel in 1977

[Brian Walden]

I can see an immedaite advantage in
        1 - reading in the kernel image from disk

As late as August of 1983, as that's the last time I had to do it, there were still systems in operation that you had to manually input the boot loader by hand using front panel switches.

See https://gunkies.org/wiki/PDP-11_Bootstrap_Loader

-Brian

> ron minnich rminnich at gmail.com
> Fri Sep 20 05:42:45 AEST 2024
>
>
> It's been too long. Plus, for all I know, it may have been a "wouldn't this
> be cool" project that did not work out. I don't recall that we ended up
> using it much. But that was almost 50 years ago, so your guess is as good
> as mine.
>
> It was for sure a cute hack.
>
> On Thu, Sep 19, 2024 at 12:10b /PM Noel Chiappa <jnc at mercury.lcs.mit.edu>
> wrote:
>
> >     > From: Ron Minnich
> >
> >     > Ed got tired of watching the bootstrap slowness
> >
> > This may be a dumb question (in which case, my apologies), but which part
> > of
> > booting a PDP-11 UNIX was slow? And thus, which parts did he bypass in a
> > 'quick reboot'? (I'm having a bit of a hard time working it out.) I can
> > think
> > of the following stages as potentially being 'slow':
> >
> > 1 - reading in the kernel image from disk
> > 2 - sizing/clearing main memory
> > 3 - loading running /etc/init
> > 3A - creating all the 'loqin's
> > 3B - starting all the daemons/etc with /etc/rc
> >
> > (There's obviously a conflict between 2 and 3*; one can't avoid 3* if one
> > does 2.)
> >
> > Which ones did he want to avoid?
> >
> > Avoiding 3* puts some limitations on the system, obviously, because it
> > means
> > one has to keep running processes around; the process table has to have the
> > same format (and be in the same location - or it has to be moved before the
> > new system is started). (Technically, I guess one would have to save the
> > inode and file tables, too; there isn't enough saved data in the kernel to
> > re-open files, plus there are file read/write ocation pointers, etc.)
> >
> > One could sort of do 2 also, if one were prepared to 1) swap all processes
> > out to secondary storage before 'rebooting', and ii) saving the process
> > table.
> >
> >     > But I'm wondering: is Ed's work in 1977 the first "kernel boots
> > kernel"
> >     > or was there something before?
> >
> > Are you talking about for UNIX, or across all operating systems? I don't
> > have
> > that broad a memory any more, to know - did TWENEX have something like
> > that?
> >
> >      Noel