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

Eric Lacombe
2009-04-29T14:50:20Z

Hi,

Le mardi 21 avril 2009 13:16:06 Eric Lacombe, vous avez écrit :
> Le lundi 20 avril 2009 20:22:21 Avi Kivity, vous avez écrit :
> > Eric Lacombe wrote:

[...]

> > 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 will try this but maybe what follows say that the problem is elsewhere.

I setup a minimal initramfs with busybox and my module inside.
The init script in the initramfs only mount /proc /sys, populate /dev (busybox
mdev), then execute the busybox shell.

Then when I insmod'ed my module, I had to cope with an exit reason at the very
first entry (through vmlaunch) to the VM.
This was because of the host and guest fs_selector VMCS fields, whose TI and
RPL bits were not 0.

After fixing that (setting TI and RPL bits to 0, instead of using directly fs
and gs values), the vmlaunch succeed, and I got quite the same behaviour as
when the system boots with the rootfs pointing to the hard disk, i.e. the
system works for "echo", "pwd", ... but freezes after a ls for example.

I say "quite", as I sometime got a freeze after a "echo something".
So the problem is definitely not a problem with files on the hard disk...

Do you have some new hints on what could go wrong?
And what could I try to resolve this problem?

I really need to resolve that thing, and all assistance is more than greatly
welcome ;)

Thanks in advance for your response and the time you have already spent to
help me.

Eric Lacombe