[PATCH v3 7/8] xl: add 'mtu' option to network configuration

[Paul Durrant <paul@xen.org>]

From: Paul Durrant <pdurrant@amazon.com>

This patch adds code to parse a value for MTU from the network configuration
if it is present. The documentation in xl-network-configuration.5.pod is
also modified accordingly.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Wei Liu <wl@xen.org>
Cc: Anthony PERARD <anthony.perard@citrix.com>

v3:
 - New in v3
---
 docs/man/xl-network-configuration.5.pod | 6 ++++++
 tools/xl/xl_cmdtable.c                  | 2 +-
 tools/xl/xl_parse.c                     | 2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/docs/man/xl-network-configuration.5.pod b/docs/man/xl-network-configuration.5.pod
index 0ac24c4a18..af058d4d3c 100644
--- a/docs/man/xl-network-configuration.5.pod
+++ b/docs/man/xl-network-configuration.5.pod
@@ -249,3 +249,9 @@ on the underlying netback implementation.
 Specifies the devid manually instead of letting xl choose the lowest index available.
 
 NOTE: This should not be set unless you have a reason to.
+
+=head2 mtu
+
+Specifies the MTU (i.e. the maximum size of an IP payload, exclusing headers). The
+default value is 1500 but, if the VIF is attached to a bridge, it will be set to match
+unless overridden by this parameter.
diff --git a/tools/xl/xl_cmdtable.c b/tools/xl/xl_cmdtable.c
index 08335394e5..2b8e1b321a 100644
--- a/tools/xl/xl_cmdtable.c
+++ b/tools/xl/xl_cmdtable.c
@@ -338,7 +338,7 @@ struct cmd_spec cmd_table[] = {
       "Create a new virtual network device",
       "<Domain> [type=<type>] [mac=<mac>] [bridge=<bridge>] "
       "[ip=<ip>] [script=<script>] [backend=<BackDomain>] [vifname=<name>] "
-      "[rate=<rate>] [model=<model>] [accel=<accel>]",
+      "[rate=<rate>] [model=<model>] [accel=<accel>] [mtu=<mtu>]",
     },
     { "network-list",
       &main_networklist, 0, 0,
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index 61b4ef7b7e..cae8eb679c 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -563,6 +563,8 @@ int parse_nic_config(libxl_device_nic *nic, XLU_Config **config, char *token)
         fprintf(stderr, "the accel parameter for vifs is currently not supported\n");
     } else if (MATCH_OPTION("devid", token, oparg)) {
         nic->devid = parse_ulong(oparg);
+    } else if (MATCH_OPTION("mtu", token, oparg)) {
+        nic->mtu = parse_ulong(oparg);
     } else {
         fprintf(stderr, "unrecognized argument `%s'\n", token);
         return 1;
-- 
2.20.1