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Re: [libvirt] [PATCHv4 9/9] virCaps: get rid of macPrefix field



On 03/29/13 18:39, Eric Blake wrote:
On 03/15/2013 09:26 AM, Peter Krempa wrote:
Use the virDomainXMLConf structure to hold this data and tweak the code
to avoid semantic change.

Without configuration the KVM mac prefix is used by default. I chose it
as it's in the privately administered segment so it should be usable for
any purposes.
---

Notes:
     Version 4:
     - new in series

  src/conf/capabilities.c          | 14 --------------
  src/conf/capabilities.h          |  9 ---------
  src/conf/domain_conf.c           | 26 ++++++++++++++++++++++----
  src/conf/domain_conf.h           |  3 +++
  src/esx/esx_driver.c             |  1 -
  src/libvirt_private.syms         |  3 +--
  src/libxl/libxl_conf.c           |  2 --
  src/libxl/libxl_driver.c         |  6 +++++-
  src/lxc/lxc_conf.c               |  3 ---
  src/openvz/openvz_conf.c         |  2 --
  src/openvz/openvz_driver.c       |  2 +-
  src/parallels/parallels_driver.c | 12 ++++++++----
  src/phyp/phyp_driver.c           |  4 ----
  src/qemu/qemu_capabilities.c     |  3 ---
  src/qemu/qemu_command.c          |  6 +++---
  src/vbox/vbox_tmpl.c             | 10 +++++++---
  src/vmware/vmware_conf.c         |  2 --
  src/vmx/vmx.c                    |  1 +
  src/xen/xen_driver.c             |  7 ++++++-
  src/xen/xen_hypervisor.c         |  2 --
  tests/vmx2xmltest.c              |  1 -
  tests/xml2vmxtest.c              |  1 -
  22 files changed, 57 insertions(+), 63 deletions(-)

+++ b/src/conf/domain_conf.c
@@ -800,6 +800,16 @@ virDomainXMLConfNew(virDomainDefParserConfigPtr config,
      if (xmlns)
          xmlconf->ns = *xmlns;

+    /* Technically this forbids to use one of Xerox's MAC address prefixes in
+     * our hypervisor drivers. This shouldn't ever be a problem.
+     *
+     * Use the KVM prefix as default as it's in the privately administered
+     * range */
+    if (memcmp(xmlconf->config.macPrefix,
+               (unsigned char[]) {0x00, 0x00, 0x00}, 3))
+        memcpy(xmlconf->config.macPrefix,
+               (unsigned char[]) {0x54, 0x52, 0x00}, 3);

Regarding a comment later in the review. This line is flawed and the default and most commonly used prefix should be 0x52, 0x54. ...


I don't see this C99 construct used very often; would it be any more
straightforward to write:

if (xmlconf->conf.macPrefix[0] == 0 &&
     xmlconf->conf.macPrefix[1] == 0 &&
     xmlconf->conf.macPrefix[2] == 0) {
     xmlconf->conf.macPrefix[0] = 0x54;
     xmlconf->conf.macPrefix[1] = 0x52;
}

But that's bikeshedding, so you don't necessarily have to agree.

More importantly, why the magic number '3', instead of...

+++ b/src/conf/domain_conf.h
@@ -1975,6 +1975,7 @@ struct _virDomainDefParserConfig {

      /* data */
      bool hasWideScsiBus;
+    unsigned char macPrefix[VIR_MAC_PREFIX_BUFLEN];

...the symbolic constant VIR_MAC_PREFIX_BUFLEN?

+++ b/src/esx/esx_driver.c
@@ -598,7 +598,6 @@ esxCapsInit(esxPrivate *priv)
          return NULL;
      }

-    virCapabilitiesSetMacPrefix(caps, (unsigned char[]){ 0x00, 0x0c, 0x29 });

You are removing this prefix from esx://, ...

esx uses the VMX backend to do the parsing and other stuff ... [2]



+virDomainDefParserConfig libxlDomainDefParserConfig = {
+    .macPrefix = { 0x00, 0x16, 0x3e },
+};
+


-    /* XXX shouldn't 'borrow' KVM's prefix */
-    virCapabilitiesSetMacPrefix(caps, (unsigned char []){ 0x52, 0x54, 0x00 });

This is a change to the default lxc:// prefix; since that is a semantic
change, it should probably be a separate patch.

... thus this doesn't make a semantic change. The funny stuff is that the test suite doesn't care about this kind of mistake ...

+++ b/src/vmx/vmx.c
@@ -521,6 +521,7 @@ VIR_ENUM_IMPL(virVMXControllerModelSCSI, VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LAST,

  virDomainDefParserConfig virVMXDomainDefParserConfig = {
      .hasWideScsiBus = true,
+    .macPrefix = {0x00, 0x0c, 0x29},
  };

...but adding it to vmx://.  Are you sure you did this correctly?

[2] ... so adding here is in fact accurate and also the changes in the tests confirm this.


I think you need to fix the esx vs. vmx issue in v5.


Peter


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