[TUHS] kernel boots kernel in 1977

[ron minnich]

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 12:10 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
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tuhs.org/pipermail/tuhs/attachments/20240919/f4371195/attachment.htm>