Re: [Xen-devel] [PATCH v6 05/16] tools/libxc: unused attribute in DECLARE_HYPERCALL_BUFFER_SHADOW

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Thu, 2015-05-14 at 16:55 +0800, Yang Hongyang wrote:
> There are cases where we only need to use the hypercall buffer data,
> and do not use the xc_hypercall_buffer_t struct.
> DECLARE_HYPERCALL_BUFFER_SHADOW defines a user pointer that can allow
> us to access the hypercall buffer data but it also defines a
> xc_hypercall_buffer_t that we don't use, the compiler will report arg
> unused error.
> Add __attribute__((unused)) before xc_hypercall_buffer_t to avoid
> the compiler error.
> 
> Example cases:
> In send_all_pages(), we only need to use the hypercall buffer data
> which is a dirty bitmap, we set the dirty bitmap to all dirty and call
> send_dirty_pages, we will not use the xc_hypercall_buffer_t and hypercall
> to retrieve the dirty bitmap.
> In send_some_pages(), we will also only need to use the dirty_bitmap.
> the retrieve dirty bitmap hypercall are done by the caller.
> 
> Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>

Acked-by: Ian Campbell <Ian.Campbell@xxxxxxxxxx>




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