Why a zoo of distributions with different features?

[Firestorm]

This may be a n00b question but I am slightly puzzled about this:

I assume - in my naivety - that the Linux kernel abstracts away all hardware details from a distributions system services and applications. Thus, if there already is a kernel for the Rockchip 3399 platform, why is it that there are competing efforts (default mrfixit Debian 9 vs. ayufan Ubuntu 18) where the hardware support is not identical?

I would assume every distribution is supposed to work exactly the same in terms of hardware support as long as you put the same kernel underneath. Where am I going wrong?


Also, what is the main challenge to port the up-to-date arm64 Linux kernel to the rk3399 platform? I would have assumed the vanilla kernel is missing device drivers that are specific to the rk3399 board or the Pinebook Pro as a whole but could not these be added (either right into the kernel or as modules)?

Please understand this is not critique but simply me trying to get a better insight. So far I have only used Linux distributions but never worried about kernel versions etc...

[Arwen]

<snarky>Because we like animals?</snarky>

You are right, we are getting close to mainline kernel support, 5.4. But, in the mean time we are using an older kernel, 4.4.x, probably the latest when Rockchip wrote or updated thier driver's for the RK3399. It has to be installed in to the distro, and we have several people willing to do that intigration work.

[mfritsche]

<snarky>Because we like animals?</snarky>

You are right, we are getting close to mainline kernel support, 5.4. But, in the mean time we are using an older kernel, 4.4.x, probably the latest when Rockchip wrote or updated thier driver's for the RK3399. It has to be installed in to the distro, and we have several people willing to do that intigration work.

Additionally, it's a bit of alchemy to find out which driver version (the hacked ones from RockChip, Broadcom or whoever, or the open source version in the mainline kernel) work with what version of the (often closed source blobs) of the firmware(s).

And that, kids, is the reason why general purpose ARM device just don't get off the ground: licencees of ARM cores make their chip, hack a specific x.y.z-whatever ancient linux kernel version and sell it as an "appliance". Source sometimes gets released if someone asks, but almost never updated to newer kernel versions, or even with a non-heavily-patched-hacked-and-broken version x.y.z  

It's the same for android smartphones, "NAS"-Appliances, and for all "RPI"-Replacement boards.

[Firestorm]

Additionally, it's a bit of alchemy to find out which driver version (the hacked ones from RockChip, Broadcom or whoever, or the open source version in the mainline kernel) work with what version of the (often closed source blobs) of the firmware(s).

And that, kids, is the reason why general purpose ARM device just don't get off the ground: licencees of ARM cores make their chip, hack a specific x.y.z-whatever ancient linux kernel version and sell it as an "appliance". Source sometimes gets released if someone asks, but almost never updated to newer kernel versions, or even with a non-heavily-patched-hacked-and-broken version x.y.z  

It's the same for android smartphones, "NAS"-Appliances, and for all "RPI"-Replacement boards.

That is an interesting insight, thanks :-)

I believe I have read there was also some difference in terms of HW support between the two distros offered by the community which do use the same kernel (debian and ubuntu) -- which was the origin of my question -- but now I cannot find that post anymore