On Tue, Jan 19, 2016 at 12:03:59PM +0000, Stefano Stabellini wrote: > On Mon, 18 Jan 2016, Mark Rutland wrote: > > On Mon, Jan 18, 2016 at 05:45:24PM +0000, Stefano Stabellini wrote: > > > On Mon, 18 Jan 2016, Mark Rutland wrote: > > > > On Fri, Jan 15, 2016 at 02:55:29PM +0800, Shannon Zhao wrote: > > > > > +void __init xen_efi_runtime_setup(void) > > > > > +{ > > > > > + efi.get_time = xen_efi_get_time; > > > > > + efi.set_time = xen_efi_set_time; > > > > > + efi.get_wakeup_time = xen_efi_get_wakeup_time; > > > > > + efi.set_wakeup_time = xen_efi_set_wakeup_time; > > > > > + efi.get_variable = xen_efi_get_variable; > > > > > + efi.get_next_variable = xen_efi_get_next_variable; > > > > > + efi.set_variable = xen_efi_set_variable; > > > > > + efi.query_variable_info = xen_efi_query_variable_info; > > > > > + efi.update_capsule = xen_efi_update_capsule; > > > > > + efi.query_capsule_caps = xen_efi_query_capsule_caps; > > > > > + efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count; > > > > > + efi.reset_system = NULL; > > > > > +} > > > > > > > > How do capsules work in the absence of an EFI system reset? > > > > > > Actually I don't think that capsules are available in Xen on ARM64 yet, > > > see "TODO - disabled until implemented on ARM" in > > > xen/common/efi/runtime.c. > > > > > > FYI system reset is available, but it is provided via a different > > > mechanism (HYPERVISOR_sched_op(xen_restart...) > > > > Will that trigger Xen to do the right thing to trigger capsule updates > > when implemented in Xen? Or do we need a xen_efi_reset_system? > > On ARM, to reboot the hardware, Xen calls the native PSCI system_reset > method. On x86, Xen calls efi_reset_system on EFI systems, and has > several fall backs if that doesn't work as expected (see > xen/arch/x86/shutdown.c:machine_restart). > > But on a second look it doesn't look like that the capsule hypercalls > are implemented correctly even on x86 (there is an "XXX fall through for > now" comment in the code). I guess they are not available on Xen at all > unfortunately. That is incredibly unfortunate. It effectively renders the firmware non-updateable when using Xen. > > Does that override PSCI? > > It does not, HYPERVISOR_sched_op(xen_restart,) is in addition to it. It > ends up calling the same function within Xen as PSCI system_reset. I meant within Dom0. Presumably Dom0 calls HYPERVISOR_sched_op(xen_restart,), and doesn't ever call PSCI SYSTEM_RESET? > > In machine_restart we try efi_reboot first specifically to allow for > > capsule updates. Similarly drivers/firmware/efi/reboot.c registers > > efi_power_off late in order to override anything else, though that's > > best-effort at present. > > That's very interesting. I think that Xen on ARM should follow what > Linux does and what Xen already does on x86 and try efi_reset_system > first on efi systems. I would agree. Thanks, Mark. -- 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