We've come to the point where building the browser from scratch takes more than building the OS itself.
Everybody wants to control the app platform. Every time a cross platform solutions appears everyone tries to shut it down. See: Java, Flash, etc.
The only one that platform owners couldn't really shut down (though they are getting better at it), is the web. It was considered too "dumb" to shut down and too useful to completely avoid. And bit by bit, just like the boiling frog story, people added interactivity features until we arrived where we are now. A bloated, perhaps crippled cross platform solution, but the best we have now for running things on things from embedded, mobile, desktop, etc., etc.
[1] https://stackoverflow.com/questions/226377/operating-system-... [2] http://www.phoronix.com/scan.php?page=news_item&px=MTAyNjU
That said, core-image-sato used to be just a simple demo image. In my old build system, we would build the Arago Project for a TI SoC every night and it would take a few hours but that included a lot of the DSP code as well which was really slow too. So a couple of hours on average is my guess.
This is the cross-compiler toolchain, the kernel, and about 250 external packages.
But yes, windows includes lots of API's and frameworks and GUI apps and such. Probably something comparable complexity wise would be Base+X11+(1 of KDE or Gnome)..
It doesn't. It took ~5h to build a tiny (~150 MB) complete system (Linux kernel + Yocto based "OS") from sources on 4 core PC few years ago. With modern CPU, I guess, it might be 3h or so. On the side note, the build process generated >50GB of files.
I think NetBSD took ~2.5 hours, including building its toolchain.
On my Macs I've been doing "port install -s" most of the time and I can tell you some relatively small installs can take a very long time.