Re: [Xen-devel] ãconfusedãwhat does xc_map_foreign_batch doï

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Sat, Sep 29, 2012 at 4:07 AM, éç <aware.why@xxxxxxxxx> wrote:
> Hiï all
>  In tools/libxc/xc_domain_save .c, one function called
> `map_and_save_p2m_table` where there exists a confusing problem, as is shown
> below:
>
>  621    live_p2m_frame_list =
>  622        xc_map_foreign_batch(xc_handle, dom, PROT_READ,
>  623                             p2m_frame_list_list,
>  624                             P2M_FLL_ENTRIES);
>
> memcpy(p2m_frame_list, live_p2m_frame_list, P2M_GUEST_FL_SIZE);
>
>  654    p2m = xc_map_foreign_batch(xc_handle, dom, PROT_READ,
>  655                               p2m_frame_list,
>  656                               P2M_FL_ENTRIES);
>
>
> maybe someone encountered the same problem, would you help me?

What's the problem?

> Besides, what's the difference between IOCTL_PRIVCMD_MMAP and
> IOCTL_PRIVCMD_MMAPBATCH?

IOCTL_PRIVCMD_MMAP will only map a single page; MMAPBATCH will map an
array of pages.

(To "batch" something in computing means to do a bunch of things all
together rather than doing them separately; e.g., rather than mapping
each page with a separate ioctl, you "batch" them all together in one
ioctl.)

 -George

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