rpi: switch to zstd squashfs images

[antonlacon]

For LE10.

Switch generic too? I'm not sure a user will notice but it should save bandwidth/storage on LE's end.

Benchmarks available here: #3209

[MilhouseVH]

Switch generic too?

It probably requires a little more analysis to be sure (ie. file size comparisons etc.), but I suspect we could probably switch all systems to zstd for LE10, kernel support permitting.

[CvH]

Switch generic too?
if RPi1 can handle it every other Project is fine too, i guess ?

[5schatten]

I use zstd for Generic since a while and works fine so far.

Btw. what about other ARM platforms like S905?

[CvH]

Btw. what about other ARM platforms like S905?

AML S905 is faster then RPi3+ so it should (benchmark needed) be okay, requires mainline ofc, ancient 3.14 won't do it.

[antonlacon]

Time to look at merging with LE9.2 branched?

[MilhouseVH]

With my own nightly test builds, the SYSTEM image file with zstd is reduced in size as follows:

	Before	After	Change
RPi	140MB	110MB	-30MB
RPi2	140MB	110MB	-30MB
Generic	246MB	205MB	-41MB

Handy! :)

[5schatten]

@antonlacon
I guess you can also add this to Rockchip options. I use it in my community builds and it works fine.

[antonlacon]

@Kwiboo fyi on rockchip change. Verified CONFIG_SQUASHFS_ZSTD=y was in configs, but didn't test anything past that.

This also puts all projects on zstd.

[MilhouseVH]

Is this good to go - remove block label and merge?

[antonlacon]

As far as I know, it's complete. I've used zstd on rpi since at least October, and the 1MB block size since January.

[MilhouseVH]

Thanks!