qemu: command: Remove dead code when formatting -drive

busid and unitid are ever used only if the device is an SD card due to
the check in qemuDiskBusNeedsDeviceArg. Since the SD card does not have
an bus or unit number, most of the code and command line formatter can
be removed since it will never be used.

src/qemu/qemu_command.c

@@ -1639,38 +1639,11 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
     const char *trans =
         virDomainDiskGeometryTransTypeToString(disk->geometry.trans);
     int idx = virDiskNameToIndex(disk->dst);
-    int busid = -1, unitid = -1;
     bool emitDeviceSyntax = qemuDiskBusNeedsDeviceArg(disk->bus);
 
     if (qemuBuildDriveStrValidate(disk, qemuCaps, bus, idx) < 0)
         goto error;
 
-    switch (disk->bus) {
-    case VIR_DOMAIN_DISK_BUS_SCSI:
-        busid = disk->info.addr.drive.controller;
-        unitid = disk->info.addr.drive.unit;
-        break;
-
-    case VIR_DOMAIN_DISK_BUS_IDE:
-        busid = disk->info.addr.drive.bus;
-        unitid = disk->info.addr.drive.unit;
-        break;
-
-    case VIR_DOMAIN_DISK_BUS_FDC:
-        unitid = disk->info.addr.drive.unit;
-        break;
-
-    case VIR_DOMAIN_DISK_BUS_VIRTIO:
-        idx = -1;
-        break;
-
-    case VIR_DOMAIN_DISK_BUS_XEN:
-    case VIR_DOMAIN_DISK_BUS_SD:
-        /* Xen and SD have no address type currently, so assign
-         * based on index */
-        break;
-    }
-
     if (qemuBuildDriveSourceStr(disk, cfg, &opt, qemuCaps) < 0)
         goto error;
 
@@ -1698,15 +1671,7 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
         virBufferAsprintf(&opt, ",id=%s", drivealias);
         VIR_FREE(drivealias);
     } else {
-        if (busid == -1 && unitid == -1) {
-            if (idx != -1)
-                virBufferAsprintf(&opt, ",index=%d", idx);
-        } else {
-            if (busid != -1)
-                virBufferAsprintf(&opt, ",bus=%d", busid);
-            if (unitid != -1)
-                virBufferAsprintf(&opt, ",unit=%d", unitid);
-        }
+        virBufferAsprintf(&opt, ",index=%d", idx);
     }
     if (bootable &&
         virQEMUCapsGet(qemuCaps, QEMU_CAPS_DRIVE_BOOT) &&