Re: [x86] - technical questions about HV implementation on Intel VT

Avi Kivity
2009-04-20T18:22:30Z

Eric Lacombe wrote:
> Hi,
>
> I reviewed my code (modify some things and add missing features) and made more
> tests, but I'm stuck with the same problem.
> Nonetheless, all the tests I've done seem to freeze my machine when files are
> used.
>
> When I try the commands "echo", "pwd" in the console (X is not started), the
> machine behaves nicely. When I try completion (with double-tab) on a command,
> it also works. But, when I try for instance "more help.c", the machine
> freezes, likewise when I try "more hel"+double-tab.
>

echo and pwd are part of bash, so they are probably in memory. I guess
once you go to disk things fail.

Try to boot the entire OS from initramfs (and keep it there).

> I really would appreciate some help on this.
>

This is much to complicated for drive-by debugging.

> Please, could you tell me what I could check (because I already checked a lot
> of things and can't figure out what happens)? I would also give you all the
> information you need.
>
> (Recall: When loaded, my module use VT-x to go on vmx root operation, then it
> creates a vmcs in order to execute the OS inside a VM.)
>

I imagine you have interrupts working properly? Does 'watch -d cat
/proc/interrupts' give the expected results (run it before you enter vmx
to load it into cache)?

Are you virtualizing memory, or does the guest manipulate page tables
directly?

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.