On Fri, 11 Sep 2015, Daniel Kiper wrote: > On Thu, Sep 10, 2015 at 05:23:02PM +0100, Mark Rutland wrote: > > > > C) When you could go: > > > > > > > > DT -> Discover Xen -> Xen-specific stuff -> Xen-specific EFI/ACPI discovery > > > > > > I take you mean discovering Xen with the usual Xen hypervisor node on > > > device tree. I think that C) is a good option actually. I like it. Not > > > sure why we didn't think about this earlier. Is there anything EFI or > > > ACPI which is needed before Xen support is discovered by > > > arch/arm64/kernel/setup.c:setup_arch -> xen_early_init()? > > > > Currently lots (including the memory map). With the stuff to support > > SPCR, the ACPI discovery would be moved before xen_early_init(). > > > > > If not, we could just go for this. A lot of complexity would go away. > > > > I suspect this would still be fairly complex, but would at least prevent > > the Xen-specific EFI handling from adversely affecting the native case. > > > > > > D) If you want to be generic: > > > > EFI -> EFI application -> EFI tables -> ACPI tables -> Xen-specific stuff > > > > \------------------------------------------/ > > > > (virtualize these, provide shims to Dom0, but handle > > > > everything in Xen itself) > > > > > > I think that this is good in theory but could turn out to be a lot of > > > work in practice. We could probably virtualize the RuntimeServices but > > > the BootServices are troublesome. > > > > What's troublesome with the boot services? > > > > What can't be simulated? > > How do you want to access bare metal EFI boot services from dom0 if they > were shutdown long time ago before loading dom0 image? What do you need > from EFI boot services in dom0? That's right. Trying to emulate BootServices after the real ExitBootServices has already been called seems like a very bad plan. I think that whatever interface we come up with, would need to be past ExitBootServices. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
