From ae90fc830dc58f2802360ef3822e64b0a4294af1 Mon Sep 17 00:00:00 2001
Message-Id: <ae90fc830dc58f2802360ef3822e64b0a4294af1@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 4 Sep 2018 10:38:49 +0200
Subject: [PATCH] virDomainDetachDeviceFlags: Clarify update semantics
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RHEL-7.6: https://bugzilla.redhat.com/show_bug.cgi?id=1621910
RHEL-8.0: https://bugzilla.redhat.com/show_bug.cgi?id=1603133

When users want to update a path to a CDROM they tend to
construct a very minimal XML and feed the API with it. This is
not a good practice as it breaks the assumptions the API is built
on. Most notably, leaving an element out should be treated as a
request for removal of the corresponding setting. Just like
leaving out <bandwidth/> clears out any QoS previously set.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>
(cherry picked from commit 2864b4cd1ccda9c12f0c0ceb340836c42a2a0e52)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/libvirt-domain.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index ab7266dc19..ad0ded9ee3 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -8315,6 +8315,14 @@ virDomainDetachDeviceFlags(virDomainPtr domain,
  * media, altering the graphics configuration such as password,
  * reconfiguring the NIC device backend connectivity, etc.
  *
+ * The supplied XML description of the device should contain all
+ * the information that is found in the corresponding domain XML.
+ * Leaving out any piece of information may be treated as a
+ * request for its removal, which may be denied. For instance,
+ * when users want to change CDROM media only for live XML, they
+ * must provide live disk XML as found in the corresponding live
+ * domain XML with only the disk path changed.
+ *
  * Returns 0 in case of success, -1 in case of failure.
  */
 int
-- 
2.18.0