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Re: [Xen-devel] Re: dumpcore changes -- [Xen-changelog] [xen-unstable] I

To: B Thomas <bjthomas3@xxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: dumpcore changes -- [Xen-changelog] [xen-unstable] In this patch, the xc_domain_dumpcore_via_callback() in xc_core.c of
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 18 Sep 2006 14:26:36 +0100
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Thread-topic: [Xen-devel] Re: dumpcore changes -- [Xen-changelog] [xen-unstable] In this patch, the xc_domain_dumpcore_via_callback() in xc_core.c of
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Yuk. This patch should never have been applied. It’s certainly clearly never been tested (e.g., because the iteration variable was changed from ‘i’ to ‘n’ the copy_from_domain_page() now always copies from the wrong page). Even if it did work, the interface change is more than a little questionable.

I’ll revert the patch. Thanks for flagging the issue.

 -- Keir

On 18/9/06 13:39, "B Thomas" <bjthomas3@xxxxxxxxx> wrote:

This change has the effect of adding some complexity to the callback routines. The original callback passed an opaque argument which was a private item for the use of the controlling mechanism and its callback function.  This change removes this and specifies only an fd.  While it's possible for the controlling mechanism to use the fd as an index to find internal data structures, this is a bit more work and it's not clear to me that it makes the interface more usable. You could also easily image controlling mechanisms that did not use an fd, in which case this would simply be an "index".

This also changes the user-mode programs that might call this library.  While such changes sometimes cannot be avoided, it's certainly appealing to retain APIs where possible. (The comment should also be cleaned up)

Was there a specific reason for the interface change ?  If so, knowing more about it would help my understanding of this change.

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