These lines (in mctelem_reserve)
newhead = oldhead->mcte_next;
if (cmpxchgptr(freelp, oldhead, newhead) == oldhead) {
are racy. After you read the newhead pointer it can happen that another
flow (thread or recursive invocation) change all the list but set head
with same value. So oldhead is the same as *freelp but you are setting
a new head that could point to whatever element (even already used).
This patch use instead a bit array and atomic bit operations.
Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Reviewed-by: Liu Jinsong <jinsong.liu@intel.com>
QEMU_UPSTREAM_REVISION set back to master, to track the tip.
QEMU_TAG set to the specific changeset as is customary.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
GICH_VMCR register contains alias to important bits of GICV interface such as:
- priority mask of the CPU
- EOImode
- ...
We were safe because Linux guest always use the same value for this bits.
When new guests will handle priority or change EOI mode, VCPU interrupt
management will be in a wrong state.
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
The current implementation of raw_copy_guest helper may lead to data corruption
and sometimes Xen crash when the guest virtual address is not aligned to
PAGE_SIZE.
When the total length is higher than a page, the length to read is badly
compute with
min(len, (unsigned)(PAGE_SIZE - offset))
As the offset is only computed one time per function, if the start address was
not aligned to PAGE_SIZE, we can end up in same iteration:
- to read accross page boundary => xen crash
- read the previous page => data corruption
This issue can be resolved by setting offset to 0 at the end of the first
iteration. Indeed, after it, the virtual guest address is always aligned
to PAGE_SIZE.
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: George Dunlap <george.dunlap@citrix.com>
[ ijc -- duplicated the comment in the other two functions with this behaviour ]
The commit 09bb434748
"Nested VMX: prohibit virtual vmentry/vmexit during IO emulation"
assumes that the HVM paths are only taken by HVM guests. With the PVH
enabled that is no longer the case - which means that we do not have
to have the IO-backend device (QEMU) enabled.
As such, that patch can crash the hypervisor:
Xen call trace:
[<ffff82d0801ddd9a>] nvmx_switch_guest+0x4d/0x903
[<ffff82d0801de95b>] vmx_asm_vmexit_handler+0x4b/0xc0
Pagetable walk from 000000000000001e:
L4[0x000] = 0000000000000000 ffffffffffffffff
****************************************
Panic on CPU 7:
FATAL PAGE FAULT
[error_code=0000]
Faulting linear address: 000000000000001e
****************************************
as we do not have an io based backend. In the case that the
PVH guest does run an HVM guest inside it - we need to do
further work to suport this - and for now the check will
bail us out.
We also fix spelling mistakes and the sentence structure.
Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: "Zhang, Yang Z" <yang.z.zhang@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
And in HAP enabled domain, it modifies all EPT entries to clear write bit
to make sure it is readonly. This will cause problem if VT-d shares page
table with EPT: the device may issue a DMA write request, then VT-d engine
tells it the target memory is readonly and result in VT-d fault.
Currnetly, there are two places will enable log dirty mode: migration and vram
tracking. Migration with device assigned is not allowed, so it is ok. For vram,
it doesn't need to set all memory to readonly. Only track the vram range is enough.
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Acked-by: Tim Deegan <tim@xen.org>
Cset fca49a00 ("netbsd: build fix with gcc 4.5") changed the
definition of va_start() to use __builtin_va_start() rather than
__builtin_stdarg_start() for GCCs >= 4.5, but in fact GCC dropped
__builtin_stdarg_start() before v3.3.
Signed-off-by: Tim Deegan <tim@xen.org>
Tested-by: Roger Pau Monné <roger.pau@citrix.com>
disk=[ ' target=/dev/loop0 ' ] will fail to parse because
'/dev/loop ' does not exist.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
We already have our own versions of the stdarg/stdbool definitions, for
systems where those headers are installed in /usr/include.
On linux, they're typically installed in compiler-specific paths, but
finding them has proved unreliable. Drop that and use our own versions
everywhere.
Signed-off-by: Tim Deegan <tim@xen.org>
Tested-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Keir Fraser <keir@xen.org>
The automatic shutdown feature of the vTPM was removed because it
interfered with pv-grub measurement support and was also not triggered
if the guest did not use the vTPM. Virtual TPM domains will need to be
shut down or destroyed on guest shutdown via a script or other user
action.
This also fixes an incorrect reference to the vTPM being PV-only.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
VF's memory space offset can be greater than 4GB and therefore needs
to be stored in a 64-bit variable.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
ARM does not (currently) support migration, so stop offering tasty looking
treats like "xl migrate".
Apart from the UI improvement my intention is to use this in osstest to detect
whether to attempt the save/restore/migrate tests.
Other than the additions of the #define/#ifdef there is a tiny bit of code
motion ("dump-core" in the command list and core_dump_domain in the
implementations) which serves to put ifdeffable bits next to each other.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Avoid freeing info then returning it to the caller.
This is XSA-88.
Coverity-ID: 1056192
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Having this here means we have to wait for a push gate pass, or fart
about which explicit pushes to master, to make an RC. The boot
messages for git builds already contain the git revision (as a
shorthash).
I will change the tarball creation checklist to seddery the -rc back
to -rcN, along with the other release-management-related changes (like
using an embedded copy of qemu).
If this patch meets with approval it should be thrown into the push
gate today, along with the patch for XSA-88, and then hopefully
nothing much else, so that we can get something suitable for making an
RC from by Friday.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Release-Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Commit 5148b7b5 ("blkif: add indirect descriptors interface to public
headers") added this without really explaining why it is needed: The
structure is identical to struct blkif_request_segment apart from the
padding field not being given a name in the pre-existing type. Their
size and alignment - which are what is relevant - are identical as long
as __alignof__(uint32_t) == 4 (which I think we rely upon in various
other places, so we can take as given).
Also correct a few minor glitches in the description, including for it
to no longer assume PAGE_SIZE == 4096.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
The term "flush" is slightly ambiguous. The correct ARM term for for this
operaton is clean, as opposed to clean+invalidate for which we also now have a
function.
This is a pure rename, no functional change.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
This reverts commit 89eb02c220.
This approach has a short coming in that it breaks when a guest enables its
MMU (SCTLR.M, disabling HCR.DC) without enabling caches (SCTLR.C) first/at the
same time. It turns out that FreeBSD does this.
This has now been fixed (yet) another way (third time is the charm!) so remove
this support. The original commit contained some fixes which are still
relevant even with the revert of the bulk of the patch:
- Correction to HSR_SYSREG_CRN_MASK
- Rename of HSR_SYSCTL macros to avoid naming clash
- Definition of some additional cp reg specifications
Since these are still useful they are not reverted.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
Guests are initially started with caches disabled and so we need to make sure
they see consistent data in RAM (requiring a cache clean) but also that they
do not have old stale data suddenly appear in the caches when they enable
their caches (requiring the invalidate).
This can be split into two halves. First we must flush each page as it is
allocated to the guest. It is not sufficient to do the flush at scrub time
since this will miss pages which are ballooned out by the guest (where the
guest must scrub if it cares about not leaking the pagecontent). We need to
clean as well as invalidate to make sure that any scrubbing which has occured
gets committed to real RAM. To achieve this add a new cacheflush_page function,
which is a stub on x86.
Secondly we need to flush anything which the domain builder touches, which we
do via a new domctl.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Cc: keir@xen.org
This has other uses other than during relinquish, so rename it for clarity.
This is a pure rename.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
This function hasn't been only about creating for quite a while.
This is purely a rename.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
When DOM0 device tree is building, the properties for initrd will
only be added if there is a linux command line. This will result to a panic
later:
(XEN) *** LOADING DOMAIN 0 ***
(XEN) Populate P2M 0x20000000->0x40000000 (1:1 mapping for dom0)
(XEN) Loading kernel from boot module 2
(XEN) Loading zImage from 0000000001000000 to 0000000027c00000-0000000027eafb48
(XEN) Loading dom0 initrd from 0000000002000000 to 0x0000000028200000-0x0000000028c00000
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) Cannot fix up "linux,initrd-start" property
(XEN) ****************************************
(XEN)
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
The function should return an error when flask_security_make_bools()
fails as well as when the input ID is out of range.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Plus, in the case of security_preserve_bools(), prevent double freeing
in the case of security_get_bools() failing.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
... but interrupt remapping is requested (with per-device remapping
tables). Without it, the timer interrupt is usually not working.
Inspired by Linux'es "iommu/amd: Work around wrong IOAPIC device-id in
IVRS table" (commit c2ff5cf5294bcbd7fa50f7d860e90a66db7e5059) by Joerg
Roedel <joerg.roedel@amd.com>.
Reported-by: Eric Houby <ehouby@yahoo.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Eric Houby <ehouby@yahoo.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Workaround for the Erratum will be in BIOSes spun only after
Jan 2014 onwards. But initial production parts shipped in 2013
itself. Since there is a coverage hole, we should carry this fix
in software in case BIOS does not do the right thing or someone
is using old BIOS.
Description:
Processor does not ensure DRAM scrub read/write sequence is atomic wrt
accesses to CC6 save state area. Therefore if a concurrent scrub
read/write access is to same address the entry may appear as if it is
not written. This quirk applies to Fam16h models 00h-0Fh
See "Revision Guide" for AMD F16h models 00h-0fh, document 51810 rev.
3.04, Nov 2013.
Equivalent Linux patch link:
http://marc.info/?l=linux-kernel&m=139066012217149&w=2
Tested the patch on Fam16h server platform and it works fine.
Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Corrected checking for boot CPU. Made warning message conditional.
Compacted warning message text. Moved comment to commit message.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
The test programs were getting the proper libxenlight.so on their link
line. Filter it out. Also change the soname of the test library to
match the real one, so that libxutil is satisfied with it.
Reported-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
We need to include the new TEST_PROG_OBJS and LIBXL_TEST_OBJS in the
appropriate dependencies. Otherwise we risk trying to build the test
program before gentypes is run.
Reported-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
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>
Since the string size is being specified by the guest, we must range
check it properly before doing allocations based on it. While for the
two cases that are exposed only to trusted guests (via policy
restriction) this just uses an arbitrary upper limit (PAGE_SIZE), for
the FLASK_[GS]ETBOOL case (which any guest can use) the upper limit
gets enforced based on the longest name across all boolean settings.
This is XSA-84.
Reported-by: Matthew Daley <mattd@bugfuzz.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
When a timeout has occurred, it is deregistered. However, we failed
to record this fact by updating etime->func. As a result,
libxl__ev_time_isregistered would say `true' for a timeout which has
already happened.
It is necessary to clear etime->func before the callback, because the
callback might want to reinstate the timeout, or might free the etime
(or its containing struct) entirely.
The results are that we might try to have the timeout occur again
(causing problems for the call site), and/or corrupt the timeout list.
This fixes the timedereg event system unit test.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Bring together the two places where etime->func() is called into a new
function time_occurs. For one call site this is pure code motion.
For the other the only semantic change is the introduction of a new
debugging message.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Test timeout deregistration idempotency. In the current tree this
test fails because ev->func is not cleared, meaning that a timeout
can be removed from the list more than once, corrupting the list.
It is necessary to use multiple timeouts to demonstrate this bug,
because removing the very same entry twice from a list in quick
succession, without modifying the list in other ways in between,
doesn't actually corrupt the list. (Since removing an entry from a
doubly-linked list just copies next and back from the disappearing
entry into its neighbours.)
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
We provide a new LIBXL_TESTS facility in the Makefile.
Also provide some helpful common routines for unit tests to use.
We don't want to put the weird test case entrypoints and the weird
test case code in the main libxl.so library. Symbol hiding prevents
us from simply directly linking the libxl_test_FOO.o in later. So
instead we provide a special library libxenlight_test.so which is used
only locally.
There are not yet any test cases defined; that will come in the next
patch.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Use the new libxl__pipe_nonblock and _close functions, rather than
open coding the same logic. Now the pipe is nonblocking, which avoids
a race which could result in libxl deadlocking in a multithreaded
program.
Reported-by: Jim Fehlig <jfehlig@suse.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Break out the pipe creation and destruction from the poller code
into two new functions libxl__pipe_nonblock and libxl__pipe_close.
Also change direct use of pipe() to libxl_pipe.
No overall functional difference other than minor differences in exact
log messages.
Also move libxl__self_pipe_wakeup and libxl__self_pipe_eatall into the
new pipe utilities section in libxl_event.c; this is pure code motion.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
--
v3: Mention that we switched pipe() -> libxl_pipe()
Previously, an application which had multiple libxl ctxs in multiple
threads, would have to itself plumb SIGCHLD through to each ctx.
Instead, permit multiple libxl ctxs to all share the SIGCHLD handler.
We keep a list of all the ctxs which are interested in SIGCHLD and
notify all of their self-pipes.
In more detail:
* sigchld_owner, the ctx* of the SIGCHLD owner, is replaced by
sigchld_users, a list of SIGCHLD users.
* Each ctx keeps track of whether it is on the users list, so that
libxl__sigchld_needed and libxl__sigchld_notneeded now instead of
idempotently installing and removing the handler, idempotently add
or remove the ctx from the list.
We ensure that we always have the SIGCHLD handler installed
iff the sigchld_users list is nonempty. To make this a bit
easier we make sigchld_installhandler_core and
sigchld_removehandler_core idempotent.
Specifically, the call sites for sigchld_installhandler_core and
sigchld_removehandler_core are updated to manipulate sigchld_users
and only call the install or remove functions as applicable.
* In the signal handler we walk the list of SIGCHLD users and write
to each of their self-pipes. That means that we need to arrange to
defer SIGCHLD when we are manipulating the list (to avoid the
signal handler interrupting our list manipulation); this is quite
tiresome to arrange.
The code as written will, on the first installation of the SIGCHLD
handler, firstly install the real handler, then immediately replace
it with the deferral handler. Doing it this way makes the code
clearer as it makes the SIGCHLD deferral machinery much more
self-contained (and hence easier to reason about).
* The first part of libxl__sigchld_notneeded is broken out into a new
function sigchld_user_remove (which is also needed during for
postfork). And of course that first part of the function is now
rather different, as explained above.
* sigchld_installhandler_core no longer takes the gc argument,
because it now deals with SIGCHLD for all ctxs.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---
v3: Include bugfixes from "Fixup SIGCHLD sharing" patch:
* Use a mutex for defer_sigchld, to guard against concurrency
between the thread calling defer_sigchld and an instance of the
primary signal handler on another thread.
* libxl_sigchld_owner_libxl_always is incompatible with SIGCHLD
sharing. Document this correctly.
Fix "have have" error in comment.
Move removal of newly unused variables to previous patch.
v2.1: Provide feature test macro LIBXL_HAVE_SIGCHLD_SHARING
We are going to want introduce another call site in the final
substantive patch.
Pure code motion; no functional change.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
---
v3: Remove now-unused variables from sigchld_installhandler_core
We are going to change these functions so that different libxl ctx's
can share a single SIGCHLD handler. Rename them now to a new name
which doesn't imply unconditional handler installation or removal.
Also note in the comments that they are idempotent.
No functional change.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
This is the feature test macro for libxl_childproc_sigchld_occurred
and libxl_sigchld_owner_libxl_always_selective_reap.
It is split out into this separate patch because: a single feature
test is sensible because we do not intend anyone to release or ship
libxl versions with one of these but not the other; but, the two
features are in separate patches for clarity; and, this just makes
reading the actual code easier.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Applications exist which want to use libxl in an event-driven mode but
which do not integrate child termination into their event system, but
instead reap all their own children synchronously.
In such an application libxl must own SIGCHLD but avoid reaping any
children that don't belong to libxl.
Provide libxl_sigchld_owner_libxl_always_selective_reap which has this
behaviour.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
---
v2: Document the new mode in the big "Subprocess handling" comment.
Frediano Ziglio