[Xen-devel] Re: [Qemu-devel] [PATCH 1/4] xen: introduce mc146818rtcxen

[Anthony Liguori <anthony@xxxxxxxxxxxxx>]

On 11/15/2011 08:51 AM, stefano.stabellini@xxxxxxxxxxxxx wrote:
> From: Stefano Stabellini<stefano.stabellini@xxxxxxxxxxxxx>
>
> Xen doesn't need full RTC emulation in Qemu because the RTC is already
> emulated by the hypervisor. In particular we want to avoid the timers
> initialization so that Qemu doesn't need to wake up needlessly.
>
> Signed-off-by: Stefano Stabellini<stefano.stabellini@xxxxxxxxxxxxx>
Yuck.  There's got to be a better way to do this.

I think it would be better to name timers and then in Xen specific machine code, 
disable the RTC timers.
Regards,

Anthony Liguori

> ---
>   hw/mc146818rtc.c |   36 +++++++++++++++++++++++++++++++++++-
>   1 files changed, 35 insertions(+), 1 deletions(-)
>
> diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
> index 2aaca2f..91242d0 100644
> --- a/hw/mc146818rtc.c
> +++ b/hw/mc146818rtc.c
> @@ -28,6 +28,7 @@
>   #include "apic.h"
>   #include "isa.h"
>   #include "mc146818rtc.h"
> +#include "arch_init.h"
>
>   //#define DEBUG_CMOS
>   //#define DEBUG_COALESCED
> @@ -614,6 +615,17 @@ static const MemoryRegionOps cmos_ops = {
>       .old_portio = cmos_portio
>   };
>
> +static int rtcxen_initfn(ISADevice *dev)
> +{
> +    int base = 0x70;
> +    RTCState *s = DO_UPCAST(RTCState, dev, dev);
> +
> +    memory_region_init_io(&s->io,&cmos_ops, s, "rtc", 2);
> +    isa_register_ioport(dev,&s->io, base);
> +
> +    return 0;
> +}
> +
>   static int rtc_initfn(ISADevice *dev)
>   {
>       RTCState *s = DO_UPCAST(RTCState, dev, dev);
> @@ -655,7 +667,11 @@ ISADevice *rtc_init(int base_year, qemu_irq intercept_irq)
>       ISADevice *dev;
>       RTCState *s;
>
> -    dev = isa_create("mc146818rtc");
> +    if (xen_available()) {
> +        dev = isa_create("mc146818rtcxen");
> +    } else {
> +        dev = isa_create("mc146818rtc");
> +    }
>       s = DO_UPCAST(RTCState, dev, dev);
>       qdev_prop_set_int32(&dev->qdev, "base_year", base_year);
>       qdev_init_nofail(&dev->qdev);
> @@ -684,3 +700,21 @@ static void mc146818rtc_register(void)
>       isa_qdev_register(&mc146818rtc_info);
>   }
>   device_init(mc146818rtc_register)
> +
> +static ISADeviceInfo mc146818rtcxen_info = {
> +    .qdev.name     = "mc146818rtcxen",
> +    .qdev.size     = sizeof(RTCState),
> +    .qdev.no_user  = 1,
> +    .qdev.vmsd     =&vmstate_rtc,
> +    .init          = rtcxen_initfn,
> +    .qdev.props    = (Property[]) {
> +        DEFINE_PROP_INT32("base_year", RTCState, base_year, 1980),
> +        DEFINE_PROP_END_OF_LIST(),
> +    }
> +};
> +
> +static void mc146818rtcxen_register(void)
> +{
> +    isa_qdev_register(&mc146818rtcxen_info);
> +}
> +device_init(mc146818rtcxen_register)

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