Also, what is the situation like with regard to figuring out what has been changed in a vendor-supplied kernel vs. a generic kernel source tree? Is it reasonably straightforward to get a clean diff so you can see what was changed? Non-upstreamed hacks and bodges seem less terrible to me if it's possible to at least see how they work.
You can usually download and diff the source tarballs. Some vendors keep git repos so you can see changelogs as well. There's usually a lot of noise in there though, lots of various imported vendor drivers that duplicate things, firmware files in hexdump format, etc. It's pretty common to see diffs of millions of lines.
I'm really curious, because it seems that Android has built an architecture where vendor supplied drivers (binary blobs?) can be dropped in without too much changes. But upstream linux needs a considerable amount of rework to "absorb" a driver.
Is this deliberate (the same reason why GCC is obfuscated) or is there a technical reason behind it ?
Because Android Linux works on thousands of different platforms with a lot of stability - I'm beginning to think that the Android driver model is superior... and perhaps mainstream Linux would do well to move to that.
There can also be a perception it's "a waste of time" since "nobody will run another kernel on this anyways"