[Minios-devel] [PATCH v4 0/<VARIOUS>] Begin to disentangle libxenctrl and provide some stable libraries

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

In <1431963008.4944.80.camel@xxxxxxxxxx> I proposed stabilising some
parts of the libxenctrl API/ABI by disaggregating into separate
libraries.

This is v4 of that set of series against:
    xen
    qemu-xen
    qemu-xen-traditional
    mini-os

NB: Samuel+minios-devel will only get the mini-os side and Stefano+qemu
-devel the qemu-xen side.

The code in for all repos can be found in:

git://xenbits.xen.org/people/ianc/libxenctrl-split/xen.git                  v4
git://xenbits.xen.org/people/ianc/libxenctrl-split/qemu-xen.git             v4
git://xenbits.xen.org/people/ianc/libxenctrl-split/qemu-xen-traditional.git v4
git://xenbits.xen.org/people/ianc/libxenctrl-split/mini-os.git              v4

The tip of the xen.git branch contains an extra patch hacking Config.mk
to point to all the others above, which should get the correct things for
the HEAD of the branch, but not further back in time.

The new libraries here are:

 * libxentoollog: Common logging infrastructure
 * libxenevtchn: Userspace access to evtchns (via /dev/xen/evtchn etc)
 * libxengnttab: Userspace access to grant tables (via /dev/xen/gnt??? etc)
 * libxencall: Making hypercalls (i.e. the IOCTL_PRIVCMD_HYPERCALL type
   functionality)
 * libxenforeignmemory: Privileged mappings of foreign memory
   (IOCTL_PRIVCMD_MMAP et al)

The first three were actually pretty distinct within libxenctrl already and
have not changed in quite some time.

Although the other two are somewhat new they are based on top of long
standing stable ioctls, which gives me some confidence.

Nonetheless I would appreciate extra review of at least the interface
headers of all of these with a particular eye to the suitability of these
interfaces being maintained in an ABI (_B_, not _P_) stable way going
forward.

Still to come would be libraries for specific out of tree purposes
(device model, kexec), which would be adding new library at the same
level as libxc I think, rather than underneath, i.e. also using the
libraries split out here, but hopefully not libxenctrl itself.

The new libraries use linker version-scripts to hopefully make future
ABI changes be possible in a compatible way.

Since last time I have:

 * Addressed various review comments:
    * Addressed feedback from Stefano on the qemu-xen series (and this
      version now goes to qemu-devel too)
    * Switched the foreign mapping interfaces to use size_t for the number
      of pages.
    * Fixed the callers of xenforeignmemory_unmap (should have been pages,
      but everywhere was passing bytes like the previous munmap case)
    * HACK patch in xen.git now updates Config.mk instead of .config

The whole thing has been build tested on Linux (incl stubdoms), and on
FreeBSD. I have runtime tested older versions on Linux but my test boxes
are currently in some netherworld having been moved to a different colo.

Neither NetBSD nor Solaris have been tested at all. It's certainly not
impossible that I've not got the #includes in the new files quite right.

http://xenbits.xen.org/people/ianc/libxenctrl-split/v4.html is the document
I've been using to try and track what I'm doing. It may not be all that
useful. The history of it is in the v4-with-doc branch of the xen.git
linked to above.

Ian.

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