Re: [Xen-devel] [PATCH] xen/arm: remove check for generic timer support for arm64

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Vijay,

On 06/02/2014 09:37 AM, vijay.kilari@xxxxxxxxx wrote:
> From: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>
> 
> arm64 always supports generic timer. So check is not required
> for arm64. For platforms which supports only aarch64 mode this
> check always passes and panics

You should explain why it always panics... i.e On AArch-64 only
implementation, this register is RES0.

A link to the ARM ARM section might be also useful.

> Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@xxxxxxxxxxxxxxxxxx>
> ---
>  xen/arch/arm/time.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/xen/arch/arm/time.c b/xen/arch/arm/time.c
> index 4c3e1a6..801c130 100644
> --- a/xen/arch/arm/time.c
> +++ b/xen/arch/arm/time.c
> @@ -138,8 +138,10 @@ int __init init_xen_time(void)
>          panic("Timer: Cannot initialize platform timer");
>  
>      /* Check that this CPU supports the Generic Timer interface */
> +#ifdef CONFIG_ARM_32

With this solution, you don't check aarch32 generic timer support on an
ARMv8 host.

I think you have to do smth like:

if ( cpu_has_aarch32 && !cpu_has_gentimer )

>      if ( !cpu_has_gentimer )
>          panic("CPU does not support the Generic Timer v1 interface");
> +#endif
>      res = dt_property_read_u32(dev, "clock-frequency", &rate);
>      if ( res )
> 

Regards,

-- 
Julien Grall

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