Re: [Qemu-devel] [PATCH 1.1 1/4] xen: do not initialize the interval timer and PCSPK emulator

[Anthony Liguori]

On 05/09/2012 07:44 AM, Stefano Stabellini wrote:
> PIT and PCSPK are emulated by the hypervisor so we don't need to emulate
> them in Qemu: this patch prevents Qemu from waking up needlessly at
> PIT_FREQ on Xen.
>
> Signed-off-by: Stefano Stabellini<address@hidden>
> ---
>   hw/pc.c |   23 +++++++++++++----------
>   1 files changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/hw/pc.c b/hw/pc.c
> index 4d34a33..c52caf6 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -47,6 +47,7 @@
>   #include "ui/qemu-spice.h"
>   #include "memory.h"
>   #include "exec-memory.h"
> +#include "arch_init.h"
>
>   /* output Bochs bios info messages */
>   //#define DEBUG_BIOS
> @@ -1097,7 +1098,7 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi,
>       qemu_irq pit_alt_irq = NULL;
>       qemu_irq rtc_irq = NULL;
>       qemu_irq *a20_line;
> -    ISADevice *i8042, *port92, *vmmouse, *pit;
> +    ISADevice *i8042, *port92, *vmmouse, *pit = NULL;
>       qemu_irq *cpu_exit_irq;
>
>       register_ioport_write(0x80, 1, 1, ioport80_write, NULL);
> @@ -1126,16 +1127,18 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq 
> *gsi,
>
>       qemu_register_boot_set(pc_boot_set, *rtc_state);
>
> -    if (kvm_irqchip_in_kernel()) {
> -        pit = kvm_pit_init(isa_bus, 0x40);
> -    } else {
> -        pit = pit_init(isa_bus, 0x40, pit_isa_irq, pit_alt_irq);
> -    }
> -    if (hpet) {
> -        /* connect PIT to output control line of the HPET */
> -        qdev_connect_gpio_out(hpet, 0, qdev_get_gpio_in(&pit->qdev, 0));
> +    if (!xen_available()) {

Shouldn't this be xen_enabled()?

Regards,

Anthony Liguori

> +        if (kvm_irqchip_in_kernel()) {
> +            pit = kvm_pit_init(isa_bus, 0x40);
> +        } else {
> +            pit = pit_init(isa_bus, 0x40, pit_isa_irq, pit_alt_irq);
> +        }
> +        if (hpet) {
> +            /* connect PIT to output control line of the HPET */
> +            qdev_connect_gpio_out(hpet, 0, qdev_get_gpio_in(&pit->qdev, 0));
> +        }
> +        pcspk_init(isa_bus, pit);
>       }
> -    pcspk_init(isa_bus, pit);
>
>       for(i = 0; i<  MAX_SERIAL_PORTS; i++) {
>           if (serial_hds[i]) {