Re: [Qemu-ppc] [PATCH] spapr: Don't use the "dual" interrupt controller mode with an old hypervisor

[Cédric Le Goater]

>                         kernel_irqchip
> 
>            (default) 
> ic-mode     allowed           off            on 
> 
> dual        XICS KVM       XICS emul.(3)   XICS KVM         (default mode)
> xics        XICS KVM       XICS emul.      XICS KVM    
> xive        XIVE emul.(1)  XIVE emul.     QEMU failure (2)
> 
> 
> (1) QEMU warns with "warning: kernel_irqchip requested but unavailable: 
>     IRQ_XIVE capability must be present for KVM" 
> (2) QEMU fails with "kernel_irqchip requested but unavailable: 
>     IRQ_XIVE capability must be present for KVM" 
> (3) That is wrong I think, we should get XIVE emulated.
> 
> 
> what you would want is XIVE emulation when ic-mode=dual and 
> kernel_irqchip=allowed, which is the behavior with this patch (but there
                                                 ^
                                              without
> are reboot bugs)