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Re: [Xen-devel] [PATCH] Use a single mmap interface in libxc

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Use a single mmap interface in libxc
From: Patrick Colp <Patrick.Colp@xxxxxxxxxx>
Date: Mon, 20 Jul 2009 10:47:56 +0100
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The idea is that the privcmd interface can also only have one mmap function instead of two (something to be done to privcmd in pvops). This simplifies things and removes unnecessary redundant code. While map_batch might not be the ideal interface, I think it's a step in the right direction, anyway.

Also, for the project I'm working on, I need to intercept mmap calls. This required me to have to put similar code in two places and, as it turned out, modifying the mmap_foreign_range functions was going to be difficult. mmap_batch can do everything required for map_foreign_range (and more), so it seemed like the thing to do was to use that for everything so there was just the one call into privcmd (and just one spot to edit code).


Keir Fraser wrote:
On 20/07/2009 10:27, "Patrick Colp" <Patrick.Colp@xxxxxxxxxx> wrote:

# HG changeset patch
# User Patrick Colp <Patrick.Colp@xxxxxxxxxx>
# Date 1248081941 -3600
# Node ID 8e1301247d784ffb98b0721d9f6f46daa0640af1
# Parent  91407452cdb62f427c74e227956dc34a107cab46
Use a single mmap interface in libxc.

This patch modifies xc_map_foreign_range and xc_map_foreign_ranges to call
mmap_map_foreign_batch. This eliminates the need for multiple privcmd mmap
ioctls. Now only IOCTL_PRIVCMD_MMAPBATCH is required.

Some explanation of why this is a useful improvement would be nice.

 -- Keir

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