Proposal for virtual devices

[michel.ponceau@xxxxxxxx]

I previously made a proposal for block devices. It was rejected because it was VBD-specific and Xen-specific. Here is a proposal for transparent interface with Xen or other. The virtual device attributes (VDA) are transferred from/to application without considering their meaning, except backend domain, previously requested to be the name for user, while it is the ID for Xen.

typedef struct virVDA { /* virtual device attribute */
    char name[16];
    char value[64];
} virVDA;

int virDomainGetVdevs(virDomainPtr domain, char *type, virVDA *attr, int maxattr);
 * @type: pointer to device type, "disk", "network" ...
 * @attr: pointer to an array of virVDA structures
 * @maxattr: number of structures in attr array
 * Return: (number of VDAs per device)<<16 + (number of devices), if success;
 *    -1 if failure.
For "disk" type, Xen provides the following VDA names:
    "virtual-device"  (virtual device number)
    "backend-id"      (backend domain ID)
    "state"
    "backend"         (backend device or file)
    "ring-ref"
    "event-channel"
This function changes "backend-id" to "bkdom-name" and translates value ID into name.

int virDomainCreateVdev(virDomainPtr domain, char *type, virVDA *attr, int nbattr);
 * @type: pointer to device type, "disk", "network" ...
 * @attr: pointer to an array of virVDA structures
 * @nbattr: number of structures in attr array
For "disk" type, Xen requires the following VDA names:
    "uname"    (backend device, value either "phy:<>" or "file:<>"
    "dev"      (virtual device number)
    "mode"     (value "ro" for read-only, or "rw" for read/write)
    "backend"  (backend domain ID)
This function translates "backend" user value (name) into ID.

int virDomainDestroyVdev(virDomainPtr domain, char *type, char *ref);
 * @type: pointer to device type, "disk", "network" ...
 * @ref: pointer to virtual device reference (number for Xen...)