Re: [EXT] no HDMI on rpi4b NetBSD 10.1

[Steve Rikli <sr%genyosha.net@localhost>]

On Tue, Jul 15, 2025 at 08:14:18AM +0200, Ramiro Aceves wrote:
> El 14/7/25 a las 23:00, Steve Rikli escribió:
> > On Mon, Jul 14, 2025 at 04:21:50PM +0000, Kulesa, Craig A - (ckulesa) wrote:
> > ...
> > > - Install the NetBSD image file to microSD, then mount its msdos
> > >   partition and unzip the RPI4 UEFI files into it.  Then you can boot
> > >   both UEFI and NetBSD from the same microSD.  This minimizes hardware
> > >   footprint at the expense of more complexity and a large hit to drive
> > >   speed.
> > 
> > Is is possible to simply unzip the RPi4_UEFI_Firmware_v1.42.zip archive
> > into a running NetBSD system's msdos /boot/ directory, and then reboot?
> > Or it it better to do that "offline", with the microSD mounted in
> > another system?
> 
> I have done it in a running system and reboot without problems. Also
> Offline.

Good to know. I was planning to experiment "live" + reboot to start.

> > I note that the zip archive and msdos partition /boot/ directory from
> > the NetBSD img have different layouts and content, but there's some
> > overlap; here's what I have from the booted NetBSD arm64.img
> > installation:
> > ...
> > If I simply unpack the zip archive directly into /boot/, it will
> > overwrite the config.txt which came with NetBSD img; and also end up
> > with different copies of at least bcm2711-rpi-4-b.dtb in /boot/ as well
> > as in /boot/dtb/broadcom/ .
> 
> I think that config.txt overwritting is needed in order to make UEFI work.
> Compare UEFI firmare zip file  config.txt with the NetBSD supplied one and
> you will see the difference. Keep a copy of yours just in case you need
> something. I have only changed arm_boost=1 to arm_boost=0 to not stress my
> RPi too much on long compilation.

Lacking other feedback, I was thinking I'd use the config.txt from UEFI zip
as-is, and potentially merge the NetBSD options back in, depending how it
goes.

Wrt the NetBSD arm64.img /boot/config.txt, I noticed especially:

    os_prefix=dtb/broadcom/
    cmdline=../../cmdline.txt
    kernel=/netbsd.img
    kernel_address=0x200000

and in the NetBSD arm64.img /boot/cmdline.txt file there is:

    root=NAME=netbsd-root console=fb

which looks like the NetBSD "/" partition location and presumably default
console definition. That seems important at first glance.

Fwiw I briefly checked config.txt docs when this rpi4 had the stock
Raspbian on it; config.txt appears to offer some functionality here which
is provided on other platforms by the NetBSD /boot.cfg file. Probably I
should revisit those config.txt docs at this point.  :-)

I expect there are many ways to craft config.txt plus associated UEFI
binaries, config, dtb, and support files to achieve various results.

> > Should the existing /boot/ content be removed first? I.e. empty out
> > the /boot/ directory which came with NetBSD img, and then unzip the
> > new UEFI archive into it?
> 
> Good question, UEFI instructions say it should work, but I have not tested.
> I have never understood dtb files. My understanding of all of this subject
> is very limited. Hope not having said something wrong.
> All of this is very  is a bit difficult for me to understand. We need better
> documentation.

The docs I've seen so far about unpacking UEFI zip files seem a little
imprecise, or assume eg. you'll be unpacking the zip bundle into a
newly-formatted (i.e. empty) fat/msdos partition.

NetBSD wiki (https://wiki.netbsd.org/ports/evbarm/raspberry_pi/) has
this to say:

"Write the UEFI firmware to the SD card. Then either insert a USB drive
with the standard NetBSD arm64.img written to it, or have the FFS
partition from that image on the rest of the uSD card. The RPI will then
boot from that filesystem.

No specifics about what to do with the existing /boot/ from arm64.img ,
though I think that somewhat implies it will be unused (ignored?).

> > > Regardless, I recommend booting to the UEFI screen (via serial console
> > > or HDMI) and configuring UEFI as desired (to remove the 3 GB RAM
> > > limit, set boot order, verify the ACPI mapping to allow the wifi chip
> > > to attach, etc) -- then have it boot NetBSD from whichever device
> > > holds NetBSD.   Doing it in two stages helps debugging later.
> > 
> > I don't know how to "boot to the UEFI screen" yet, but perhaps this
> > will become clearer after installing and booting the UEFI zip bundle?
> 
> You will see inmediately at boot a screen with a big raspberry from which
> you can enter UEFI, similar to a PC BIOS (pressing F2 perhaps? I do not
> remember exactly the keys).

Got it -- we'll see. :-)  I tried this rpi4 with no boot media to check
what the onboard firmware offered, but it doesn't seem to be interactive,
just diagnostic messages.

Cheers,
sr.