Export seL4 config values

[midnightveil]

au-ts/sddf#255 (comment)

Export the values from gen_config.json et al for use.

[Ivan-Velickovic]

I don't know if there's anything really for the tool to do here, it's a JSON struct that is part of the SDK, I don't know what the tool would be abstracting.

[midnightveil]

Not abstracting, just providing the data as an interface so one doesn't have to locate the file and parse it for every use.

Maybe that fits somewhere else?

Like what would have to happen is meta.py would need to locate (1) microkit SDK, (2) board folder (3) gen_config.json for the right config, (4) parse json.

[Ivan-Velickovic]

The tool would have to know 1 and 2 in order to provide an interface anyways so all it would be doing is providing an interface for parsing the JSON which is typically trivial anyways? (just trying to understand what the tool would actually be providing the user)

[Ivan-Velickovic]

For your example, right now it would be:

import json

config = json.load(f"{sdk_path}/board/{board}/{config}/include/sel4/gen_config.json"})
config["MAX_NUM_NODES"]

I don't know what the tool could do to actually make this process easier.

[Ivan-Velickovic]

Or did you mean to abstract certain common flags such as how many cores are used, etc?

[midnightveil]

I mean things like error handling (not done there) and knowledge of that path existing (which there evidently isn't).

I guess this could be solved with a copy-pastable snippet that does all that, but like, why?

(Also, the sdfgen tooling needs to know the board and config doesn't exist? How else does it parse a DTS and driver config files?)

[Ivan-Velickovic]

(Also, the sdfgen tooling needs to know the board and config doesn't exist? How else does it parse a DTS and driver config files?)

The tool doesn't have knowledge of the SDK path, board, or the Microkit config right now, there isn't anything that it needs it for. Although maybe that will change in the future, but right now it's not needed so I didn't add it.

For using sDDF, the DTS is provided by the build-system to the metaprogram, it doesn't pick which DTS to use.

I mean things like error handling (not done there)

I'm not sure what you mean by error handling, I don't know what errors there would be to handle.

and knowledge of that path existing (which there evidently isn't).

Right, I guess we should document the file's existence in the Microkit manual. Maybe it is worth having some KernelConfig or KernelInfo struct that has these fields.