Re: annual HOWTO rampage, mini edition

[Greg Troxel <gdt%lexort.com@localhost>]

As usual, I'm trimming things when I have nothing to say to them.

"Greg A. Woods" <woods%planix.ca@localhost> writes:

> BTW, the following sentence is not exactly right:
>
> 	Xen when using a vga console does not process console input.

Are you saying that during xen boot but before reliquishing you can type
at xen on the console and do things?

Or that you can pass a xen config option to tell xen to keep the
console?  If you do, can you +++ to get to xen, and does the rest go to
xencons?

> We need to note that Xen (at least since 4.13) hides the COM port it is
> using from the dom0.  I.e. by default NetBSD-XEN3_DOM0 can't see any
> "com0", period.

Added a note; I see com0 missing one mine.

> So, when using a serial console (on the first COM port), booting a
> XEN3_DOM0 kernel with "console=com0" actually attaches the console to
> xencons(4) (as it's the only active and present console device and the
> requested device is not found).  The "console=com0" parameter, if given,
> is ignored.

ok, but this seems like a consequence of defaults in a broken setup, and
not what we want to instruct.  The howto is about how to do it right.

> I've also confirmed that "console=xencons" is redundant and unnecessary
> when using a serial console (at least with recent-ish NetBSD, probably
> 9.x and newer, but maybe going back much further).

Because vga is witheld if xen is serial, or because xencons is higher
priority, or ?

> So in the current version of the HowTo the sample /boot.cfg line should
> have the "console=com0" part removed, and I would leave out the
> "console=com1" part for Xen since in Xen the default is "vga,com1", and
> one can normally also leave out anything about UART settings since that
> should already have been set properly by /boot (as per the earlier
> advice of having GENERIC boot with the correct console).
>
> 	menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M
>
> The paragraph of description for this example needs to be rewritten too:
>
> 	If using a serial console the Xen kernel manages the serial port
> 	and connects it to the NetBSD-XEN3_DOM0 xencons(4) device.  The
> 	UART settings can be explicitly reset by the Xen kernel (see
> 	xen-command-line(7)), but the settings done by the NetBSD /boot
> 	program should persist and will be used by Xen.

Partially adapted, with some questions left.  I am not entirely ok with
your drive to leave everything to defaults without explaining.

> We should also fix the Xentools package(s) to install
> xen-command-line(7) and try to upstream that fix.

ENOPATCH!

> I think the last paragraph about problems with a default console and
> differences with GENERIC can simply be removed.

I think that's gone.

> It might be worth mentioning somewhere that NetBSD-XEN3_DOMU kernels
> always uses xencons(4) as the console device, perhaps in the section
> describing the interactions with the domU console.

added.

> Is it worth mentioning that "xl shutdown" of a domU only works if
> powerd(8) is running, or is that now considered to be a default and
> assumed part of any NetBSD installation?

I think it's normal.


I think I made progress and got most of your points in.  Surely more
remains to be done but I'm trying to be careful to only write things I
understand as the point is to bring clarity to people that don't know
what's going on in the first place.
Feel free to follow up with  corrections, on list or privately if too
minor.