vbox6-block: hang in linux kernel boot

As I mentioned, I got vbox6-block to boot using 4 block devices. It boots grub, and I can transfer control to Ubuntu 22.04. I used recovery mode to get a little more info about what's going on.

Then after a bit it hangs.

The genode logs show lots of "preemption during measurement" warnings. The linux kernel log shows stuff like...

start_kernel+0x49a/0x4ca ... Spectre V2 : ... Filling RSB on VMEXIT ... smpboot: CPU0: Intel(R) Core(TM) i5-3320M CPU @ 2.60GHz ...

and then... nothing.

suggestions?

For more config, logs and a screenshot, see... https://github.com/dckc/madmode-blog/issues/49#issuecomment-1409922456