Re: "Boot this kernel once" functionality? (amd64)

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Wed, Sep 16, 2020 at 12:20:57 +0200, Anthony Mallet wrote:

> On Wednesday 16 Sep 2020, at 12:09, Martin Husemann wrote:
> > This works fine on e.g. sparc*; I can do: shutdown -b netbsd.t -r
> > now
> >
> > No state is modified on any disks, very convenient.
> 
> Right, not changing any state seems safer!
> 
> > I don't know if there is enough of a persistent environment for UEFI
> > boots (I would guess there is), and probably no easy way for BIOS
> > boot.
> 
> The machine in question is not UEFI, so I would be more interested in
> a pure BIOS solution.

As der Mouse mentioned upthread, kloader(4) would seem like a
promising candidate to implement this.  It doesn't support x86
currently, but existing kloader_machdep.c files are minuscule - the
non-boilerplate code is essentially just one function that is
essentially a bit more than a fancy memcpy.  The realy interesting
question is if NetBSD on a given platform leaves the machine in a
state that a newly booted kernel expects the machine to be in.  The
hpc* ports that support kloader do not expect anything much from the
initial state of the machine.

Of course that doesn't suit your immediate needs...

-uwe