Re: Selecting the scheduler from boot menu

I can do the lua stuff for this

Warner

On Sat, Jan 31, 2026, 3:27 PM Milan Obuch <freebsd-hackers@dino.sk> wrote:

> On Sat, 31 Jan 2026 23:15:49 +0100
> Milan Obuch <freebsd-hackers@dino.sk> wrote:
>
> > On Sat, 31 Jan 2026 12:44:07 -0800
> > Steve Kargl <kargls@comcast.net> wrote:
> >
> > > On 1/31/26 12:35, Milan Obuch wrote:
> > > > On Sat, 31 Jan 2026 12:21:59 -0800
> > > > Steve Kargl <kargls@comcast.net> wrote:
> > > >
> > > >> All,
> > > >>
> > > >> Is it possible modify the boot menu to select 4BSD or ULE during
> > > >> the boot process?  I've looked at the code in src/stand/forth,
> > > >> but unfortunately the language is foreign to me. Currently, one
> > > >> boots into FreeBSD, checks the kern.sched.name, and then may
> > > >> need to edit /boot/loader.conf to change to the other scheduler,
> > > >> and then reboot.
> > > >
> > > > Which version are you working on? I think something recent, maybe
> > > > 16-CURRENT. Loader was rewritten in lua some time ago.
> > >
> > > I'm looking at src/stand/forth, particular, menu-commands.4th.
> >
> > Somehow, those old files are still present and installed, but no
> > longer used in boot process unless some non-standard build or
> > configuration is being used.
> >
> > > If the boot menu is written in lua, it's still a foreign language to
> > > me. So, I would need some guidance on how to hack the menu up.
> > >
> > > Yes, it is a convenience to have menu item. Dropping to the loader
> > > prompt is possible. Taking it to a logical extreme, let's retire the
> > > menu because everything can be set at the loader prompt.
> >
> > I'll try to look there. I did not actually read files in /boot/lua
> > directory yet, but I have some lua experience and maybe I can come
> > with something if nobody acts quicker... but first I nedd to
> > understand the process.
> >
>
> There is menu.lua file with all boot menu related functionality. Now
> the question is, where should the new option go - there is main menu
> loaded upon start, and then options menu could be invoked from there.
> As an option for 4BSD/ULE scheduler selection, it should go probably to
> the later. A word of warning, all options changed via options menu are
> not persistent, so on next reboot default value (with possible override
> by config file vale) is used.
>
> Regards,
> Milan
>
>