On 6 August 2013 11:05, Rob Herring robherring2@gmail.com wrote:
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On 08/05/2013 04:41 PM, Dennis Gilmore wrote:
Hi all,
As part of the unified features in u-boot thread I said that I would work to get distros to agree to a common location that u-boot will be able to assume exists for it to transparently load dtbs from for us.
I would like to propose /boot/dtb/
I think it needs to be in /boot/ to allow for booting from systems with / and /boot on separate partitions. I believe Ubuntu and hence Debian put them in /lib somewhere today. Fedora puts them in /boot/dtb-<kernel version>. im not sure where the other distros put them.
A DTB should not be tied to a kernel version. I realize that is a reality for some boards, but lets not encourage that. There are also plans to remove dts files from the kernel.
I think that until they are decoupled from the kernel Fedora would have /boot/dtb be a symlink to the latest installed kernel. once its decoupled it would be the location where the dtbs are installed.
If /boot/dtb is THE dtb to use, does more than that need to be specified (at least from a bootloader perspective).
If I understood you correctly, that'd be needlessly limiting one image to one board.
Consider an SD Card + CONFIG_ARCH_MULTIPLATFORM kernel you can pull out and plug in to use on a variety of different boards, the bootloader would need to identify the correct dtb and pass it to the kernel.
U-Boot is bound up with compile-time decisions about targeting a single board at the moment, but if we're talking about long term decisions like /boot/dtb/ just like ARM isn't the only consideration U-Boot is not the only bootloader.
Once kernels capable of running a single binary on many platforms are common (they're already workable) pressure for the bootloader to do likewise will increase. So it'd be a shame to block that by choosing a dtb convention that assumes there's only one on the image.
-Andy