On 03/09/12 16:30, Ian Campbell wrote:
On Mon, 2012-09-03 at 16:00 +0100, Marc Zyngier wrote:
On 03/09/12 14:30, Ian Campbell wrote:
Until we know what bootloaders are going to become common in the ARM servers world it hard to know who we should be working with to define a proper protocol going forward and which bootloaders to supply patches for etc. If anyone has any pointers that would be very useful.
I don't have any useful insight about bootloaders (I tend to hate them all ;-), but what we (KVM/ARM) need is something that implements the "boot in HYP mode" thing, as described here:
https://lists.cs.columbia.edu/pipermail/kvmarm/2012-August/002829.html
From a discussion with Stefano last week, it looks like this protocol can fit Xen as well, but it would be nice to have a formal Ack before we push this into RMK's patch system.
Yes, Xen needs this "boot in hyp mode" functionality as well, which AIUI is main core of the proposal. The bits about leaving a stub hypervisor behind when the kernel then drops to SVC mode is really an internal Linux/KVM implementation detail. Xen expects to be launched in hyp mode and will stay there, it launches the domain 0 kernel in svc mode (so under Xen the kernel never sees hyp mode).
The proposal in https://lists.cs.columbia.edu/pipermail/kvmarm/2012-August/002828.html seems consistent with Xen's requirements to me, both for the hypervisor itself and the guest kernels (including dom0).
Right, this is exactly what I wanted to know. I just wanted to make sure the kernel and Xen didn't have diverging requirements.
Sorry for hijacking this thread... ;-)
Thanks,
M.