On Mon, Oct 21, 2013 at 04:40:15PM -0400, Nicolas Pitre wrote: > On Mon, 21 Oct 2013, Stephen Warren wrote: [...] > > but taking the big picture into > > account, observe that we make life a lot more difficult for distros, > > since they need to get the device tree from somewhere. Distros now are > > forced to work out which DTB goes with which board, > > This is not a new problem. Before you had to figure out which kernel > would go with which board. You still need to match kernels to boards even with DT. It's no good if you provide a full DTB that describes your hardware if the kernel doesn't support any of it. > > or perhaps we need > > to define a firmware interface to obtain the DTB and pass it to the > > kernel. > > That's the bootloader's job. Nothing magical actually: just have U-Boot > or whatever load the DTB from some flash area. I agree. I think most if not all architectures that support DT have long had some interface on how to pass a DTB to the kernel. At least I know that ARM and x86 have, but I'm pretty sure that PowerPC, SPARC and others do too. > > I > > think we can still have a hack-free, churn-free, multi-platform kernel > > without requiring DT, but by using board files. > > I kinda agree with you, but this is too late for that now. > > We have DT, and the best way forward is to fix the process which is, > arguably, somewhat obstructive and broken at the moment. I agree that the process could use some enhancements. But I also think that we should be open to move away from DT again if it turns out to not be a good enough solution. "It's too late" doesn't sound like a very good argument to me. Essentially DT is just a different way to represent what we used to have in platform data, so we haven't fundamentally changed anything at that level. Well, we've made things worse to some degree. Thierry
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