CVA6: Infrastructure improvements

[MarioOpenHWGroup]

Some improvements in the current infrastructure:

• Auto detect CV_SW_PREFIX if not set.
• Set RISCV_GCC and RISCV_OBJCOPY if not set.
• Avoid return statements when fatal errors.
• Detection of the tohost addr now has more compatibility across systems.
• Other improvements.

[MarioOpenHWGroup]

@cathales if you could take another look it would be great 😄

[MikeOpenHWGroup]

Hey @MarioOpenHWGroup and @cathales, there are multiple "conversations" in this PR (which is a good thing). I believe some of them are now fixed, but it is hard to tell. Please use the "Resolve conversation" button to close discussions that are resolved. Thanks.

[MarioOpenHWGroup]

Hey @MarioOpenHWGroup and @cathales, there are multiple "conversations" in this PR (which is a good thing). I believe some of them are now fixed, but it is hard to tell. Please use the "Resolve conversation" button to close discussions that are resolved. Thanks.

For sure, I have resolved all the issues in the thread 👍

[MarioOpenHWGroup]

@cathales a final revision would be appreciated 😃

[cathales]

@MikeOpenHWGroup I wanted to mark conversations as resolved but I am not allowed to do so.

PR LGTM, I think it would be great if @ASintzoff could have a look too, as he is one of the original authors.

[MikeOpenHWGroup]

@MikeOpenHWGroup I wanted to mark conversations as resolved but I am not allowed to do so.

Yes, this is a strange GitHub feature: You can resolve a conversation in a pull request if you opened the pull request or if you have write access to the repository where the pull request was opened. In this context, "write access" is a someone who can approve a pull-request (a Committer). I think this is broken.

[ASintzoff]

LGTM