virtme-configkernel: disable lockdep by default

[kuba-moo]

Sort of an "RFC" posting. We (netdev) use vng to run networking tests in two flavors - normal and debug. I was surprised to see lockdep splats in the "normal" one.

Commit cd3c35c ("virtme-configkernel: enable lockdep by default") enabled lockdep, and no doubt lockdep is a useful tool. But it's a bit surprising that lockdep is enabled on a normal vng build. I would have expected "vanilla vng build" to be pretty close to kvm_guest.config. lockdep slows down the kernel, eats memory and is not exactly free of false positives.

[arighi]

Glad to know that you guys are using vng in netdev!

So, the reason why lockdep is enabled by default is mostly because of my typical use case: debugging (that includes catching potential locking issues in advance). And that was added before having the --config option.

Considering that now we can easily do something like this to re-enable lockdep:

$ echo CONFIG_PROVE_LOCKING=y > /tmp/vng.config
$ vng -vb --config /tmp/vng.config

The other thing to consider is performance. People are starting to use vng not just to test kernels, but also to test how a certain software, application, etc. works with a specific kernel, so providing a default config that pays attention to performance can be beneficial.

All that said, I have to admit that I'm not against this change. I left a comment in the review, if you can fix that I'd be happy to merge this. Thanks.

[kuba-moo]

GitHub says "No reviews" to me, where do I look?

[arighi]

@kuba-moo oh well, I'll just comment here, it looks like your commit is trying to change also virtme-ng-init, I'm expecting to see a change only in configkernel.py, maybe you need to refresh your local git repo and rebase your change.

[kuba-moo]

Ah, right, sorry. Fixed.