Right, you can do it that way...

I guess many will object to the idea of ProtoBuffers (specially in kernel) because of its reliance non-mainstream compiler/binutils. Anything that requires more than gcc will probably not get a lot of support, specially if/when it is used only for the logging backend.

Maybe I should have rephrased my wish this way:
A gcc plugin that compiles .proto files directly will be very interesting.
Having Qt in mind, C lovers do not like to see not-exactly-C syntax in their code. Therefore a combination of limited (yes non-arbitrary) C structures and compiler pargmas (for example to specify that a field is optional, and what is the default) instead of .proto syntax, along with the above mentioned plugin will be even more attractive, and likely to be taken into kernel. Here I assumed kernel hackers love C, and I should confess I do not know how powerful gcc plugins are.