[Xen-devel] [PATCH 1/5] xen: Always calculate max_cpus value

Jan Beulich JBeulich at suse.com
Thu Jul 5 11:56:39 EDT 2012


>>> On 05.07.12 at 17:00, Daniel Kiper <daniel.kiper at oracle.com> wrote:
> max_cpus is not available since 20374 changeset (Miscellaneous data
> placement adjustments). It was moved to __initdata section. This section
> is freed after Xen initialization. Assume that max_cpus is always
> equal to XEN_HYPER_SIZE(cpumask_t) * 8.

Using nr_cpu_ids, when available, would seem a better fit. And
I donm't see why, on dumps from old hypervisors, you wouldn't
want to continue using max_cpus. Oh, wait, I see - you would
have to be able to tell whether it actually sits in .init.data, which
might not be strait forward.

Jan

> Signed-off-by: Daniel Kiper <daniel.kiper at oracle.com>
> 
> diff -Npru crash-6.0.8.orig/xen_hyper.c crash-6.0.8/xen_hyper.c
> --- crash-6.0.8.orig/xen_hyper.c	2012-06-29 16:59:18.000000000 +0200
> +++ crash-6.0.8/xen_hyper.c	2012-07-05 14:52:59.000000000 +0200
> @@ -1879,11 +1879,9 @@ xen_hyper_get_cpu_info(void)
>  	uint *cpu_idx;
>  	int i, j, cpus;
>  
> -	get_symbol_data("max_cpus", sizeof(xht->max_cpus), &xht->max_cpus);
>  	XEN_HYPER_STRUCT_SIZE_INIT(cpumask_t, "cpumask_t");
> -	if (XEN_HYPER_SIZE(cpumask_t) * 8 > xht->max_cpus) {
> -		xht->max_cpus = XEN_HYPER_SIZE(cpumask_t) * 8;
> -	}
> +	xht->max_cpus = XEN_HYPER_SIZE(cpumask_t) * 8;
> +
>  	if (xht->cpumask) {
>  		free(xht->cpumask);
>  	}
> 
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