Re: [Xen-devel] [PATCH QEMU-XEN v3 3/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_bulk

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2015-10-14 at 15:01 +0100, Stefano Stabellini wrote:
> On Wed, 7 Oct 2015, Ian Campbell wrote:
> > In Xen 4.7 we are refactoring parts libxenctrl into a number of
> > separate libraries which will provide backward and forward API and ABI
> > compatiblity.
> > 
> > One such library will be libxenforeignmemory which provides access to
> > privileged foreign mappings and which will provide an interface
> > equivalent to xc_map_foreign_bulk.
> > 
> > In preparation for this switch all uses of xc_map_foreign_range to
> > xc_map_foreign_bulk. 
> 
> The sentence is incomplete.

If you mean "grammatically incorrect" then I don't think it is. Did you
mean it was missing some information which you hoped to to see? If so then
which?

> Unfortunately xc_map_foreign_bulk is not that well documented, but I am
> assuming that the mfn parameter is not supposed to be changed by the
> function, right?

Given:

/**
 * Like xc_map_foreign_pages(), except it can succeed partially.
 * When a page cannot be mapped, its respective field in @err is
 * set to the corresponding errno value.
 */
void *xc_map_foreign_bulk(xc_interface *xch, uint32_t dom, int prot,
                          const xen_pfn_t *arr, int *err, unsigned int num);

by "the mfn parameter" I suppose you mean arr[0] (for cases where arr is
passed as &mfn as below)?

That's a pointer to an array of const xen_pfn_t so no need to worry about
it changing, unlike some other interfaces per-page errors are reported via
the separate err array.

Ian.

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