Add network support to Pi2/3

[hardillb]

Also include most of the changes needed for Qemu 5.1 from #20 as needed for USB support (with the resize increased to 4G and moved to apply to passed in images as well as the included one).

Should have the included image updated to match latest at time of release.

Device comes up as usb0 but close enough to get started.

I did test with Qemu 5.2-rc3 to see if Pi4 support was included but doesn't look like it yet.

[hardillb]

I've moved the resize to only be applied for Pi3 (64bit builds) as it's only needed there and it now resizes the image to the closest next 2G increment rather than fixed at 4G (the lite image is good at 2G)

I also bumped to the latest 32bit Lite image for the full build with included disk image

[davystrong]

Any chance of this getting merged?

[jeremypoulter]

For what it is worth I tried this and can confirm it is working

[lukechilds]

Thanks for the review @jeremypoulter and thanks again for working on this @hardillb. Apologies for how long it's taken for me to review, I'm really busy with @getumbrel at the moment. No promises, but I've put a note in my calendar to try and take the time to review, test and merge this at the weekend.

[lukechilds]

Thanks for this awesome PR!

Some small changes.

[lukechilds]

Thanks so much for your help with this @hardillb!

This looks all good to me now, are you able to give my latest changes a quick eyeball and let me know if anything looks off to you?

[hardillb]

I'm out and about for a few hours, I can give it a proper look when i get back home

[hardillb]

All looks good

The only thing I noticed, it looks like the pi3 option will only work with the 64bit RaspiOS builds not the 32bit builds because it's using the kernel8.img but looking at the history this would have been the case before the merge so not a regression.

[lukechilds]

I think the current images are 32bit, they're working ok for me.

[lukechilds]

kernel8.img is included in the image so wouldn't this be 32 bit or 64 bit depending on which image is being used?

[hardillb]

You can get 64bit images here https://downloads.raspberrypi.org/raspios_arm64/images/ they are just not listed on the download pages yet.

Running the vm image against a 32bit image hangs and maxes out the CPUs for me.
e.g.

docker run --name dockerpi -it --rm -v `pwd`/2021-03-04-raspios-buster-armhf-lite.img:/sdcard/filesystem.img ben/dockerpi:vm pi3

Hangs here:

...
Searching for kernel='kernel8.img'
Searching for dtb='bcm2710-rpi-3-b-plus.dtb'
Booting QEMU machine "raspi3b" with kernel=/fat/kernel8.img dtb=/fat/bcm2710-rpi-3-b-plus.dtb

[lukechilds]

Strange, 32 bit works fine for me: 2021-03-04-raspios-buster-armhf-lite.zip

But I get a kernel panic (no hanging) with 64 bit: 2021-03-04-raspios-buster-arm64.zip.

Ah well, like you said, this is already the current behaviour, so I'll go ahead and merge this PR. Thanks again for your help!