Commit Graph
36 Commits
Author SHA1 Message Date
Marek Marczykowski-Górecki b72624aad5 libvchan: create xenstore entries in one transaction
This will prevent race when client waits for server with xs_watch - all
entries should appear at once.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2018-11-01 10:21:00 +00:00
Wei Liu c66d9982eb tools: bump library version numbers to 4.12
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
2018-07-13 08:39:35 +01:00
Wei Liu 73d1f55efc tools: bump library version numbers to 4.11
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
2018-01-24 12:41:21 +00:00
Ross Lagerwall 6b6500b3cb tools/libs/evtchn: Add support for restricting a handle
Implement support for restricting evtchn handles to a particular domain
on Linux by calling the IOCTL_EVTCHN_RESTRICT_DOMID ioctl (support added
in Linux v4.8).

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Release-acked-by: Julien Grall <julien.grall@linaro.org>
2017-10-27 15:06:39 +01:00
Ian Jackson fff4aa914d DEPS handling: Use DEPS_INCLUDE everywhere
DEPS_INCLUDE is currently the same as DEPS, so no functional change.

This patch is the result of this perl rune:

  git-grep -l 'include.*DEPS' | xargs perl -i -pe 'next unless m/^-?include/; s/\bDEPS\b/DEPS_INCLUDE/'

I have verified that I haven't missed anything, with this rune:

  git-grep '\bDEPS\b'

Reported-by: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2017-09-07 16:21:54 +01:00
Ian Jackson 300929f6e4 DEPS handling: Use DEPS_RM everywhere
DEPS_RM is currently the same as DEPS, so no functional change.

This patch is the result of two perl runes:

  git-grep -l 'rm.*DEPS' | xargs perl -i~ -pe 'next unless m/^\t+rm\b/; s/\bDEPS\b/DEPS_RM/;'

  git-grep -l 'RM.*DEPS' | xargs perl -i~ -pe 'next unless m/^\t+\$\(RM\)/; s/\bDEPS\b/DEPS_RM/;'

And editing  tools/xenstat/libxenstat/Makefile  by hand.

I verified that I didn't miss anything with this rune:

  git-grep '\bDEPS\b' | grep -v include |less

Reported-by: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2017-09-07 16:21:45 +01:00
Petre Pircalabu f2b40dabab Makefile: Fix uninstall target
Running "make uninstall" does not remove all installed files, a
situation which might cause link related issues if xen is re-installed
in a different location.
In order to make uninstall correctly remove the files it is best
the process should be done recursively by mirroring each "install"
target with an "uninstall" who removes the installed files.

An exception to this rule is uninstalling the files produced by
"qemu-xen-dir-remote" and "qemu-xen-traditional-dir", which are external
to the project. These projects do not implement an "uninstall" target so
the files have to be removed manually.

Signed-off-by: Petre Pircalabu <ppircalabu@bitdefender.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2017-07-28 17:47:42 +01:00
Marek Marczykowski-Górecki a3a87d27a3 libvchan: Fix cleanup when xc_gntshr_open failed
If xc_gntshr_open failed the only thing to cleanup is free allocated
memory. So instead of calling libxenvchan_close (which assume
valid calculated buffers being mmaped already) free memory and return.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2017-07-28 17:46:14 +01:00
Wei Liu b1e7f6e8ee tools: bump some library version numbers to 4.10
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
2017-06-07 15:20:59 +01:00
Juergen Gross 327f54ed7f tools: remove gntshr support
libgnttab contains the complete gntshr support, but the tools build
infrastructure contains dedicated support for gntshr _and_ gnttab.

Remove the gntshr specific flags and switch their users to gnttab
instead.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2017-03-15 10:31:16 +00:00
Juergen Gross 42affa826e tools: provide pkg-config file for libxenvchan
In order to be able to use pkg-config for obtaining linker- and
compiler-flags provide a xenvchan.pc file.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2017-03-14 14:13:14 +00:00
Wei Liu 8b204d3709 tools: bump some library version numbers to 4.9
Bump the version number for libxc, libxlu, libxl and libvchan to 4.9.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
2016-12-12 11:48:43 +00:00
Wei Liu d337764d9b tools: bump some library version numbers to 4.8
It is a pretty safe thing to do and would avoid accidentally overwrite
the old libraries when doing development.

Bump all version numbers that are currently 4.7 to 4.8. That includes
libxc, libxlu, libxl and libvchan.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
2016-06-14 18:32:10 +01:00
Wei Liu 116d8bab9b tools: bump library version numbers
The following libraries are checked:
1. libxc, version number bumped
2. libxl, version number bumped
3. libxlu, no development in 4.7 cycle, but depends on libxl, version
   number bumped
4. libs/*, new in 4.7 cycle, version numbers not bumped
5. libxenstore, no development in 4.7 cycle, version number not bumped
6. libxenstat, no development in 4.7 cycle, version number not bumped
7. libvchan, depends on  xengnttab library, API changed, version number
   bumped

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
2016-05-24 16:26:37 +01:00
Ian Campbell bc8baa9673 libxenevtchn: rename evtchn_port_or_errot_t as xenevtchn_port...
Otherwise the name clashes with the libxc evtchn_compat use of the
name (which is compat, so can't really change), and triggers an error
with older gcc relating to redefining typedefs (which are not allowed
per the spec, but which are tolerated by newer gcc)

None of qemu-trad, qemu-xen or mini-os actually use this type, so this
should be fine. Note that the library API is not actually stable until
4.7 is releases.

Reported-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wei.liu2@citrix.com>
2016-02-04 15:19:30 +00:00
Ian Campbell 84e0616a50 tools: avoid redefinition of typedefs
When splitting out various functionality from libxc into tools/libs/*
I attempted to make it possible to avoid callers being unnecessarily
exposed to the xentoollog interface by providing a typedef of the
xentoollog_logger handle in each of the headers.

However such typedefs are not allowed in C, instead it is necessary to
forward declare the struct and then use the struct xentoollog_logger
variant in the prototypes.

It appears that older gcc (e.g. 4.4) complains about this issue while
newer ones (e.g. 4.9) are more tolerant unless -pedantic-errors is
used, this was a deliberate change
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=ce3765bf44e49ef0568a1ad4a0b7f807591d6412

As well as tools/libs/* it is also now necessary to give libvchan the
same treatment, since it previously inhereted the typedef via one of
tools/libs/*.

Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
2016-01-25 15:45:52 +00:00
Ian Campbell a71ad0fead tools: Refactor /dev/xen/gnt{dev,shr} wrappers into libxengnttab.
libxengnttab will provide a stable API and ABI for accessing the
grant table devices.

The functions are moved into the xengnt{tab,shr} namespace to make a
clean break from libxc and avoid ambiguity regarding which interfaces
are stable.

All in-tree users are updated to use the new names.

Upon request (via #define XC_WANT_COMPAT_GNTTAB_API) libxenctrl will
provide a compat API for the old names. This is used by qemu-xen for
the time being. qemu-xen-traditional is updated in lockstep.

This leaves a few grant table related functions which go via privcmd
(GNTTABOP) rather than ioctls on the /dev/xen/gnt* devices in
libxenctrl. Specifically:

  - xc_gnttab_get_version
  - xc_gnttab_map_table_v1
  - xc_gnttab_map_table_v2
  - xc_gnttab_op

These functions do not appear to be needed by qemu-dm, qemu-pv
(provision of device model to HVM guests and PV backends respectively)
or by libvchan suggesting they are not needed by non-toolstack uses of
event channels.

The new library uses a version script to ensure that only expected
symbols are exported and to version them such that ABI guarantees can
be kept in the future.

After this change libxenvchan no longer needs to link against
libxenctrl. It still needs xenctrl.h in one file for xen_mb and
friends.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
[ ijc -- updated MINIOS_UPSTREAM_REVISION and QEMU_TRADITIONAL_REVISION ]
2016-01-22 12:22:27 +00:00
Ian Campbell b7f76a699d tools: Refactor /dev/xen/evtchn wrappers into libxenevtchn.
libxenevtchn will provide a stable API and ABI for accessing the
evtchn device.

The functions are moved into the xenevtchn namespace to make a clean
break from libxc and avoid ambiguity regarding which interfaces are
stable.

All in-tree users are updated to use the new names.

Upon request (via #define XC_WANT_COMPAT_EVTCHN_API) libxenctrl will
provide a compat API for the old names. This is used by qemu-xen for
the time being. qemu-xen-traditional is updated in lockstep.

This leaves a few event channel related functions which go via privcmd
(EVTCHNOP) rather than ioctls on the /dev/xen/evtchn device in
libxenctrl. Specifically:

 - xc_evtchn_alloc_unbound
 - xc_evtchn_reset
 - xc_evtchn_status

Note that xc_evtchn_alloc_unbound's functionality is also provided by
xenevtchn_bind_unbound_port() (née xc_evtchn_bind_unbound_port) and is
probably redundant.

These functions do not appear to be needed by qemu-dm, qemu-pv
(provision of device model to HVM guests and PV backends respectively)
or by libvchan suggesting they are not needed by non-toolstack uses of
event channels. QEMU does use these in hw/xenpv/xen_domainbuild.c but
that is a "toolstack use".

The new library uses a version script to ensure that only expected
symbols are exported and to version them such that ABI guarantees can
be kept in the future.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
[ ijc -- updated MINIOS_UPSTREAM_REVISION and QEMU_TRADITIONAL_REVISION ]
2016-01-22 12:21:07 +00:00
Konrad Rzeszutek Wilk 7d66a4ba69 libvchan: Read prod/cons only once.
We must ensure that the prod/cons are only read once and that
the compiler won't try to optimize the reads. That is split
the read of these in multiple instructions influencing later
branch code. As such insert barriers when fetching the cons
and prod index.

This is part of XSA155.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2015-12-18 09:50:02 -05:00
Ian Campbell 443701ef0c Replace FSF street address with canonical URL
As recommended in http://www.gnu.org/licenses/gpl-howto.en.html.

This is the result of:
$ git grep -El Mass\|Temple\|Franklin | xargs ./fsf.pl

Where fsf.pl is:
    #!/usr/bin/perl -w -pi.bak -0777
    my $repl = 'If not, see <http://www.gnu.org/licenses/>.';
    my $br = qr/(?:\s*\n\s*(?:[\*\#]|\/\/|\.\\" )?\s*|\s+)/;

    my $inwt = qr/[Ii]f${br}not,${br}write${br}(?:to${br})?the${br}Free${br}Software${br}Foundation,(?:${br}Inc\.,)?/;

    my $mass = qr/675${br}Mass${br}Ave,?${br}Cambridge,?${br}MA${br}02139,?${br}USA,?\.?/;
    my $franklin = qr/51${br}Franklin${br}St(?:reet)?(?:,${br}| - )Fifth${br}Floor,?${br}Boston,?${br}MA,?${br}02110-1301,?${br}USA,?\.?/;
    my $temple = qr/59${br}Temple${br}Place(?:,${br}| - )Suite${br}330,?${br}Boston,?${br}MA,?${br}021110?-1307,?${br}USA,?\.?/;

    s|$inwt$br$mass|$repl|m;
    s|$inwt$br$franklin|$repl|m;
    s|$inwt$br$temple|$repl|m;

The only remaining mentions of these addresses are in COPYING files which I
haven't touched.

Some of the changed files are imports from elsewhere, however
filtering them out is tricky, I think it is tolerable to have these
files be modified here and then perhaps reverted on the next sync,
since it's only 1-2 lines and obvious what is going on.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
2015-07-29 11:14:07 +01:00
Olaf Hering 93790b1c38 tools: replace private LIBDIR with automake libdir
Reuse automake variable instead of inventing a private variable.

The result of this command:
 git grep -wnl LIBDIR | xargs sed -i 's@LIBDIR@libdir@g'

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
2015-05-21 15:12:11 +01:00
Olaf Hering e3dcb16398 tools: replace private INCLUDEDIR with automake includedir
Reuse automake variable instead of inventing a private variable.

The result of this command:
 git grep -wnl INCLUDEDIR | xargs sed -i 's@INCLUDEDIR@includedir@g'

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
2015-05-21 15:12:10 +01:00
Jan Beulich b541d3fe1d libvchan: address compiler warnings
Both vchan_wr() and stdout_wr() should be defined with a non-empty
argument list (i.e. void). Additionally both of them as well as usage()
should be static to make clear that no other code is referencing them.

Further, statements should follow declarations.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
2015-02-05 12:21:48 +00:00
David Scott 7f6b3ca54d linux_gntshr_munmap: munmap takes a length, not a page count
This fixes a bug where if a client shares more than 1 page, the
munmap call fails to clean up everything. A process which does
a lot of sharing and unsharing can run out of resources.

This patch also fixes in-tree callers of
  - xc_gntshr_munmap
  - xc_gnttab_munmap
to supply page counts rather than lengths.

Signed-off-by: David Scott <dave.scott@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
2014-09-10 15:06:50 +01:00
Jason Andryuk 821096dd8a libvchan: Make raw_get_{data_ready, buffer_space} match
For writing into a vchan, raw_get_buffer_space used >, allowing the full
ring size to be written.  On the read side, raw_get_data_ready compared
the ring size with >=.  This mismatch means a completely filled buffer
cannot be read.  Fix this by making the size checks identical.

Signed-off-by: Jason Andryuk <andryuk@aero.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
2014-06-02 14:36:05 +01:00
Marek Marczykowski-Górecki 2efcb0193b libvchan: Fix handling of invalid ring buffer indices
The remote (hostile) process can set ring buffer indices to any value
at any time. If that happens, it is possible to get "buffer space"
(either for writing data, or ready for reading) negative or greater
than buffer size.  This will end up with buffer overflow in the second
memcpy inside of do_send/do_recv.

Fix this by introducing new available bytes accessor functions
raw_get_data_ready and raw_get_buffer_space which are robust against
mad ring states, and only return sanitised values.

Proof sketch of correctness:

Now {rd,wr}_{cons,prod} are only ever used in the raw available bytes
functions, and in do_send and do_recv.

The raw available bytes functions do unsigned arithmetic on the
returned values.  If the result is "negative" or too big it will be
>ring_size (since we used unsigned arithmetic).  Otherwise the result
is a positive in-range value representing a reasonable ring state, in
which case we can safely convert it to int (as the rest of the code
expects).

do_send and do_recv immediately mask the ring index value with the
ring size.  The result is always going to be plausible.  If the ring
state has become mad, the worst case is that our behaviour is
inconsistent with the peer's ring pointer.  I.e. we read or write to
arguably-incorrect parts of the ring - but always parts of the ring.
And of course if a peer misoperates the ring they can achieve this
effect anyway.

So the security problem is fixed.

This is XSA-86.

(The patch is essentially Ian Jackson's work, although parts of the
commit message are by Marek.)

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
2014-02-06 16:44:41 +01:00
Matthew Daley 098ef0c4d4 libvchan: tidy up usages of fcntl in select-type sample application
Namely, don't overwrite all the other flags when twiddling O_NONBLOCK,
and add basic error handling.

Coverity-ID: 1055041
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
2013-11-04 17:13:38 +00:00
Matthew Daley f2f06a2f1b libvchan: handle libxc evtchn failures properly in init functions
The reasoning behind this patch is that ctrl->event_port is a uint32_t
(ie. unsigned), so the current checks on it for negative error results,
non-negative port presence etc. are incorrect.

Fix by using evtchn_port_or_error_t in the init functions instead,
adjusting the error handling, and removing the now-unnecessary check
from the close function.

Coverity-ID: 1055609
Coverity-ID: 1055610
Coverity-ID: 1055611
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Reviewed-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
2013-10-31 21:55:53 +00:00
Ian Campbell debddaa56c nstore: rename public xenstore headers
The xenstore header xs.h is producing conflicts with other software[1].

xs is a too short identifier and does not matche the library. Renaming
the headers to xenstore.h and xenstore_lib.h is the easiest way to make
them easy recognizable and prevent furthe problems.

[1]: http://bugs.debian.org/668550

[ Also update QEMU_TAG, to bring in corresponding change to
qemu-xen-traditional. -iwj ]

Signed-off-by: Bastian Blank <waldi@debian.org>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

--HG--
rename : tools/xenstore/xs.h => tools/xenstore/xenstore.h
rename : tools/xenstore/xs_lib.h => tools/xenstore/xenstore_lib.h
2012-05-14 17:15:36 +01:00
Olaf Hering 75f1b60ed0 tools/libvchan: Remove unwanted debugging code
-O2 -Wall -Werror triggers these warnings:

io.c: In function 'do_send':
io.c:196: warning: ignoring return value of 'writev', declared with attribute warn_unused_result
io.c: In function 'do_recv':
io.c:287: warning: ignoring return value of 'writev', declared with attribute warn_unused_result

writev to -1 will always fail, silence the warning by removing the offending
(disabled) debug code.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
2012-04-17 18:18:49 +01:00
Keir Fraser acbae3dcf6 tools/libvchan: Beef up the CPU barriers in libvchan.
Although they were sufficient for x86, they weren't safe more generally.

Signed-off-by: Keir Fraser <keir@xen.org>
2012-01-21 17:15:40 +00:00
Anil Madhavapeddy 6a14fdf920 libvchan: fix segfault in client error path
In libvchan_client_init, go to the error path if the gntdev device is
not available.  Otherwise, a segfault happens later as the vchan
context is invalid.

Signed-off-by: Anil Madhavapeddy <anil@recoil.org>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
2011-11-24 19:09:55 +00:00
Ian Campbell ab375de6c2 libvchan: clean *.opic
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
2011-11-24 17:00:33 +00:00
Roger Pau Monne 9163062a39 tools/build: Introduce {PREPEND,APPEND}_{LIB,INCLUDES}
Create two new variables called APPEND_ and PREPEND_ to add compile
flags at the beginning or at the end of the search path.

Added a new semantic for user defined compile flags, here is the list
of possible options:

PREPEND_LIB: add libraries to the search path before xen
             (before xen installation folders).
PREPEND_INCLUDES: add headers to the search path before xen
                  (before xen installation folders).
APPEND_LIB: add libraries to the search path at the end
            (after all xen installation folders have been added).
APPEND_INCLUDES: add libraries to the search path at the end
                 (after all xen installation folders have been added).

EXTRA_INCLUDES and EXTRA_LIB can still be used, and they will have the
same effect as PREPEND_INCLUDES and PREPEND_LIB.

Signed-off-by: Roger Pau Monne <roger.pau@entel.upc.edu>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
2011-11-14 18:14:07 +00:00
Ian Jackson 834f076e77 libvchan: remove erroneously-committed libvchan-node[12]; add them to .hgignore
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
2011-10-07 10:47:04 +01:00
Daniel De Graaf 1a16a3351f libvchan: interdomain communications library
This library implements a bidirectional communication interface between
applications in different domains, similar to unix sockets. Data can be
sent using the byte-oriented libvchan_read/libvchan_write or the
packet-oriented libvchan_recv/libvchan_send.

Channel setup is done using a client-server model; domain IDs and a port
number must be negotiated prior to initialization. The server allocates
memory for the shared pages and determines the sizes of the
communication rings (which may span multiple pages, although the default
places rings and control within a single page).

With properly sized rings, testing has shown that this interface
provides speed comparable to pipes within a single Linux domain; it is
significantly faster than network-based communication.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
2011-10-06 19:44:40 +01:00