<joehh>
is there any documentation mapping rapberry pi kernel gpio stuff to upstream kernel gpio stuff?
<joehh>
I'm trying to get a serial port working using a raspberry pi (running aarch64 nixos image) without any success and wanting to know where to look for guidance
<samueldr>
hmm, for serial on the raspberry pi I did things as usually described
<samueldr>
do you mean accessing the raspberry pi from serial, or using it to access something else over serial?
<samueldr>
the latter, I wouldn't know for sure, but pretty confident it would work like on other raspberry pi distros
<joehh>
using pi to access other hardware over serial devices
<joehh>
ie I've a custom board with rs232 chips hooked up to the places expected when using raspian
<joehh>
I guess my next step is to boot in raspian, see what modules etc are loaded and then look to nixos to see similar
<clever>
joehh: dtb overlays are likely to play more of an impact
<clever>
thats all handled in config.txt
<joehh>
same stuff as for "standard" raspbian?
<clever>
yeah
<joehh>
great thanks - will give that a go
<clever>
thats handled by the firmware, before nixos loads, so its pretty much the same
<samueldr>
clever: doesn't u-boot load other dbts from the mainline folders with the generic distro configuration?
<samueldr>
dtbs*
<clever>
samueldr: rpi needs some config.txt flags to set the gpio secondary features, and matching dtb's to tell linux about the hardware it has enabled
<samueldr>
clever: wouldn't you need u-boot to load the right mainline dtb in that case?
<clever>
yeah, i'm not sure how u-boot plays into that...
<samueldr>
I don't have the experience and knowledge to be sure about my assumptions here :/
<joehh>
me either (yet :) ) my starting assumption is it will look similar, but be subtly different
<samueldr>
hmmmm, the ext4 image *could* go from 2.0G to 1.6G AFAICT, but resize2fs's estimation of minimum size doesn't want to go that low :(
<samueldr>
(in our case it's find since it's expanded at boot)
<samueldr>
fine*
<gchristensen>
omg what if we shipped "ISOs" which were ZFS with dedup and compression
<samueldr>
not sure if it'd make a difference compared to squashfs
<samueldr>
here it's for the sd-image which gets kinda installed in-place
<gchristensen>
probably not :( :)
<samueldr>
so can't do too much funny stuff :/
<samueldr>
e.g. not sure things like reducing block size would be a good thing
<samueldr>
though from a cursory glance, instead of 64ZiB, the fs max size would be 16ZiB