Re: [libvirt] anyone implementing host device enumeration?
On Tue, Sep 30, 2008 at 12:17:27AM -0400, David Lively wrote:
diff --git a/src/internal.h b/src/internal.h
index d96504d..9a94f6d 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -292,6 +307,25 @@ struct _virStorageVol {
};
+/**
+ * _virNodeDevice:
+ *
+ * Internal structure associated with a node device
+ */
+struct _virNodeDevice {
+ unsigned int magic; /* specific value to check */
+ int refs; /* reference count */
+ virConnectPtr conn; /* pointer back to the connection */
+ char *key; /* device key */
+ char *name; /* device name */
+ char *parent_key; /* parent device */
+ char *bus_name; /* (optional) bus name */
+ xmlNodePtr bus; /* (optional) bus descriptor */
+ char **cap_names; /* capability names (null-term) */
+ xmlNodePtr *caps; /* capability descs (null-term) */
+};
This is not the right way to maintain the internal representation of
devices.
The model we follow is to have 2, sometimes 3 structs to represent
an object. I'll summarize in terms of domain objects
- virDomainPtr - the public opaque struct representing a domain
the internal struct is defined in internal.h
and merely contains reference counting, connection
pointer, and any unique keys (ID, name, UUID).
- virDomainObjPtr - the internal struct representing the state of
a domain object. Not all drivers use us - only
stateful drivers do. It is used to track state
such as guest PID, logfile, running state,
and a pointer to the live and inactive configs
This is done in domain_conf.h/.c
- virDomainDefPtr - the internal struct representing the canonical
configuration of a domain. This is a direct
mapping of the XML into a series of structs.
This is done in domain_conf.h/.c
So, in the context for host devices we need a few changes. In the
internal.h file, you should only store the key/name attributes.
There should then be a separate file handling configuration parsing
and formatting, node_device_conf.h/.c. There is probably no need
for a state object, so skip virNodeDeviceObjPtr, and just create a
virNodeDeviceDefPtr representing the XML format as a series of
structs/unions, etc. See virDomainDefPtr for a good example. This
should not store any xmlNodePtr instances - it should be all done
as explicit struct/enum fields
The node_device_conf.c file should at mimium have 2 methods, one
for converting an XML document into a virNodeDeviceDefPtr object,
and one for the converting a virNodeDeviceObjPtr back into an XML
document. Follow the existing API naming / method signatures that
are seen in domain_conf.h / network_conf.h for current 'best practice'
Daniel
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