Re: [Xen-devel] [PATCH v3 1/3] libxl/cpumap: Add xc_cpumap_[setcpu, clearcpu, testcpu] to complement xc_cpumap_alloc.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Tue, 2015-03-24 at 11:39 -0400, Konrad Rzeszutek Wilk wrote:

Please make sure you CC all of the toolstack maintainers.

> +void xc_cpumap_clearcpu(int cpu, xc_cpumap_t map)
> +{
> +    clear_bit(cpu, (unsigned long *)map);

Is it necessary to worry about alignment here, since xc_cpumap_t is
actually a uint8_t*.

I'm afraid I think it probably is on ARM at least, which is rather
tedious.

Or do we rely on all of these always being dynamically allocated (via
xc_cpumap_alloc) and therefore "suitably aligned so that it may be
assigned to a pointer to any type of object"[0]  following calloc ,
avoids the issue in practice?

I think we probably do, does anyone disagree with that assessment?

Ian.

[0]
http://pubs.opengroup.org/onlinepubs/9699919799/functions/calloc.html#tag_16_39




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