Re: [Xen-devel] ãconfusedãwhat does xc_map_foreign_batch doï

[éç <aware.why@xxxxxxxxx>]

On Mon, Oct 1, 2012 at 10:17 PM, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> wrote:

On Sat, Sep 29, 2012 at 4:07 AM, éç <aware.why@xxxxxxxxx> wrote:
> Hiï all
> ÂIn tools/libxc/xc_domain_save .c, one function called
> `map_and_save_p2m_table` where there exists a confusing problem, as is shown
> below:
>
> Â621 Â Âlive_p2m_frame_list =
> Â622 Â Â Â Âxc_map_foreign_batch(xc_handle, dom, PROT_READ,
> Â623 Â Â Â Â Â Â Â Â Â Â Â Â Â Â p2m_frame_list_list,
> Â624 Â Â Â Â Â Â Â Â Â Â Â Â Â Â P2M_FLL_ENTRIES);
>
> memcpy(p2m_frame_list, live_p2m_frame_list, P2M_GUEST_FL_SIZE);
>
> Â654 Â Âp2m = xc_map_foreign_batch(xc_handle, dom, PROT_READ,
> Â655 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â p2m_frame_list,
> Â656 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 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.)

Â-George

Thanks, yours makes me clear and confident.
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