So, per our conversation today, lets create a new, readonly, data structure pointed to by a single field in setup_header, in order to preserve what little space we have left in that structure (a whopping 24 bytes...) The new data structure will have a header consisting of a magic number and a length field; if we want to be really paranoid we could add a checksum/crc. The existence of this new readonly structure will be announced by bumping the boot protocol to 2.15. The presence of your new boot launch capability (trenchboot) will be indicated by a new bit in xloadflags. I thought hard about this, and I have come to the conclusion that the new structure is better off in the .rodata section of the compressed kernel rather than in the setup area, for the following reasons, some of which are theoretical and unlikely to apply anywhere in the near future, but don't actually hurt to address right off the bat: a. The future size of the structure would not be artificially constrained by the 32K hard limit on the setup area; b. It is one less level of indirection in the build tools; c. It adds a possibly unnecessary dependency on the setup area, which could possibly be awkward for some boot loaders (unlikely, but...); d. It would allow this new structure to also carry information that might be useful to the decompressor for whatever reason. -hpa
