Re: [Xen-devel] [PATCH v17 14/23] x86/VPMU: Initialize VPMUs with __initcall

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.01.15 at 22:44, <boris.ostrovsky@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/vpmu.c
> +++ b/xen/arch/x86/hvm/vpmu.c
> @@ -497,3 +497,39 @@ long do_xenpmu_op(int op, 
> XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg)
>  
>      return ret;
>  }
> +
> +static int __init vpmu_init(void)
> +{
> +    int vendor = current_cpu_data.x86_vendor;
> +
> +    if ( vpmu_mode == XENPMU_MODE_OFF )
> +    {
> +        printk(XENLOG_INFO "VPMU: disabled\n");
> +        return 0;
> +    }
> +
> +    switch ( vendor )
> +    {
> +    case X86_VENDOR_AMD:
> +        if ( amd_vpmu_init() )
> +           vpmu_mode = XENPMU_MODE_OFF;
> +        break;
> +    case X86_VENDOR_INTEL:
> +        if ( core2_vpmu_init() )
> +           vpmu_mode = XENPMU_MODE_OFF;
> +        break;
> +    default:
> +        printk(XENLOG_WARNING "VPMU: Unknown CPU vendor: %d\n", vendor);
> +        vpmu_mode = XENPMU_MODE_OFF;
> +        break;

return 0;

(i.e. avoid printing another message below)

> +    }
> +
> +    if ( vpmu_mode == XENPMU_MODE_OFF )
> +        printk(XENLOG_WARNING "VPMU: Disabling due to initialization 
> error\n");

We repeatedly find that not printing at least a vague indication of
what went wrong makes problem analysis quite a bit more difficult.
It won't cost much to include the actual error code here. 

> +    else
> +        printk(XENLOG_INFO "VPMU: version %s.%s\n",
> +               __stringify(XENPMU_VER_MAJ), __stringify(XENPMU_VER_MIN));

%s and __stringify()? Either print the numbers with %d or %u, or
use __stringify() to avoid any argument besides the format string.

Jan


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