Marc Zyngier
2012-Sep-03 16:19 UTC
Re: [kvmarm] boot-wrapper: simple multi module loading support
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. -- Jazz is not dead. It just smells funny...