Hi Thiago,

So even if not ideal, the solution above is desirable for powerpc. We would 
like to preserve the ability of allowing userspace to pass parameters to the 
OS via the DTB, even if secure boot is enabled.

I would like to turn the above into a proposal:

Extend the syscall as shown in this RFC from Takahiro AKASHI, but instead of 
accepting a complete DTB from userspace, the syscall accepts a DTB 
containing only a /chosen node. If the DTB contains any other node, the 
syscall fails with EINVAL. If the DTB contains any subnode in /chosen, or if 
there's a compatible or device_type property in /chosen, the syscall fails 
with EINVAL as well.

This works for me. We could even have it as just a DTB fragment that is
merged *at* the /chosen/ node of the kernel-device tree - so would not
contain a /chosen node itself, and it would be impossible to provide
nodes outside of /chosen. Either is fine.

Thanks!


Jeremy