Re: Raspberry PI information

[mlelstv%serpens.de@localhost (Michael van Elst)]

he%NetBSD.org@localhost (Havard Eidnes) writes:

>1: status of RPI5 support:
>  As of early 2024, NetBSD does not support the Raspberry Pi 5.
>but later under "NetBSD current" (unspecified version):
>  RPI5 general support (UEFI firmware required)

>so which is it?


Both. You can boot UEFI and load netbsd, hardware support
is pretty limited.



>2: do we run on CM4?  What about CM5?  Same as RPI5?

CM5 is like RPI5.
CM4 is like RPI4.

In either case the "compute module" needs some environment,
usually a "carrier board" or "I/O board".

You won't see lots of hardware support there either.



>3: CPU types does not mention any of the RPI5 variants

The arm core is supported.



>4: UEFI in general

You need to get the proper UEFI from somewhere else.



>Under "NetBSD 10" is mentioned:
>  RPI4 general support (UEFI firmware required)

>and under "NetBSD current" is mentioned:
>  RPI5 general support (UEFI firmware required)

The official NetBSD only supports RPI4 as a generic
aarch64 server with UEFI firmware.



>There is a separate section named
>  UEFI booting
>but it is IMHO short on concrete details for how to go about
>using it.


>Later under "RPI4 xhci" is mentioned
>  One workaround is to switch to UEFI, but that leads to a 3GB
>  memory limit and needing a monitor.
>Is this still accurate?  Is it impossible to use a serial console
>when booting using the UEFI boot image?  And is the 3GB memory
>limit still a thing?  Makes it kind of pointless to try to run on
>an 8GB RPI5, no?

The 3GB issue is a hardware flaw of the RPI4. Setting the UEFI
limit was an early crude workaround. It shouldn't be required
anymore.



>5: SD card structure and booting process

>This section finishes off with a non-clickable URL to
>https://www.raspberrypi.org/documentation/configuration/config-txt/boot=
>.md

>which redirects to
>https://www.raspberrypi.com/documentation/computers/configuration.html
>and which starts by talking about raspi-config.  Is that program
>even available on NetBSD?

No.

Try:

https://www.raspberrypi.com/documentation/computers/config_txt.html#what-is-config-txt



>I also have a general sense that this section could be expanded.


>6: Ability to boot from other media?

>I've understood that microSD cards are the easiest way to boot a
>raspberry pi, but that they wear out rather quickly.

Can't tell that. I lost one card, not for wear out, but for
writing while removing power.


> How does
>one use e.g. an eMMC card instead?

eMMC devices are usually built-in. The RPI has none. You will find
adapters for SD card slots or USB and then they are used like
an SD card or a USB stick with no advantage.


> Without going the route via
>first installing Linux?  What about these newfangled nVME HATs
>available for use with the RPI5?

The RPI documentation tells you all this, it is independent of
running Linux or NetBSD.



>7: vcgencmd
>says
>  The program vcgencmd, referenced in the boot section, can be
>  found in pkgsrc/misc/raspberrypi-userland.

The userland code builds only for 32bit arm. I have a
modified version that partially runs on aarch64. But
the tool is not really useful.


>No such mention is made in the boot section, though.  And
>... what's that supposed to do?

vcgencmd sends commands to the firmware that runs on the GPU.



>   To work around bugs in hardware (that may or may not be fixed
>   in recent RPI4) and because not all OSes have workarounds, the
>   UEFI firmware's default is to limit RAM to 3GB. NetBSD 10 can
>   be used with more, so this needs to be configured in UEFI.

>How?

UEFI offers a menu when booting (similar to a PC BIOS setup).


>Does this also apply to RPI5 with -current?

No.



>10: Updating dtb files

>This whole section goes on about this without saying where these
>files are supposed to come from?!?



>11: Updating the firmware

>   It is somewhat likely that running NetBSD from a given branch
>   X with firmware from a branch Y < X will not go well. It is
>   unclear if firmware from a branch Y > X will work. It is
>   standard practice to use firmware from the right branch. An
>   alternative view is that newer firmware is usually better, and
>   the the firmware needs to be new enough for the hardware.


Firmware updates are (mostly) agnostic regarding the OS.

For RPI0-3 the firmware is on the boot disk.

For RPI4 part is on a EEPROM, there is a self-update during
the boot process. The tool to set this up is Linux only
but can easily be replicated.

For RPI5 all of the firmware is in a EEPROM. I guess NetBSD
could update it when it got support for the SPI interface.


>The first sentence is kind of scary.  However, this does not say
>where the firmware (is supposed to) come from.  Is it maintained
>inside the NetBSD source tree as a binary blob (it sounds like
>it)?

Firmware comes exclusively from Raspberry Pi, there is no
source. Fetch it from github or RPI OS.



>12: X11 on aarch64?

>Status is still "does not work"?


The RPI firmware (still) offers a dumb framebuffer that is
used for wsfb.



>Generally, I was hoping for something here which could tell me
>how to do the system-dependent tasks from NetBSD.  E.g. how does
>one go about adjusting the EEPROM settings, to enable booting
>from an nVME HAT?  I'm assuming the Linux command to edit the
>EEPROM settings is not available, since it's not mentioned?

Assuming recent firmware, the RPI5 will boot from NVME automatically,
but it's not first in the boot order.




Greetings,