Re: Debian, Qemu, KVM and Raspberry Pi
On Thu, Nov 17, 2016 at 08:21:13AM +0000, Mark Morgan Lloyd wrote:
> I'm obviously watching these ongoing threads with a lot of interest :-)
>
> If I can ask two questions so that there's a summary in a single place ready
> for me to get back onto this:
>
> * Assuming a host kernel that has apparently been built with KVM etc.,
> what's the best way to test that it exposes the required functionality?
>
> * What's the recommended Debian guest, and am I correct in assuming that
> the only indication of whether it's using KVM etc. is its speed of
> execution?
>
> I'm interested in embedding a low-traffic DMZ in a firewall, I think Qemu is
> adequate for this but wouldn't trust weaker containerisation.
KVM on arm requires:
CPUs booted in HYP mode (so boot loader has to be done right).
Kernel built with VGIC support (or in the case of the RPi 2 and 3
with emulated VGIC since it doesn't have the normal VGIC that most arm
chips have).
Either a 64 bit kernel or an lpae kernel.
New enough qemu to have support for kvm on arm (not usually a problem
anymore). RPi2/3 requires a patched one since the emulated VGIC
apparently requires qemu to be tied to specific cores so that the first
core can stay responsible for the VGIC emulation and not confuse qemu.
Really the RPi2/3 is just too weird to really support KVM due to the
lack of standard expected arm cpu features. I don't expect it to ever
have mainline kernel and qemu support due to those hardware deficiensies.
If you have an arm system that boots with the cpu in HYP mode and have
a kernel with KVM support enabled. I see the armhf lpae kernel has KVM
support enabled in debian. I don't see it in the arm64 kernel config,
so it is not enabled there yet. Probably should be.
If you have that, then you should be able to run qemu with the -enable-kvm
flag and it should work.
--
Len Sorensen
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