dragonball: update comment for init_microvm

Rewrite the comment of Vm::init_microvm method for aarch64.

Fixes cargo test warnings on aarch64.

Fixes: #6969

Signed-off-by: xuejun-xj <jiyunxue@linux.alibaba.com>

src/dragonball/src/device_manager/mod.rs

@@ -1019,6 +1019,7 @@ mod tests {
     use vm_memory::{GuestAddress, MmapRegion};
 
     use super::*;
+    #[cfg(target_arch = "x86_64")]
     use crate::vm::CpuTopology;
 
     impl DeviceManager {

src/dragonball/src/vm/aarch64.rs

@@ -99,12 +99,11 @@ impl Vm {
     /// Initialize the virtual machine instance.
     ///
     /// It initialize the virtual machine instance by:
-    /// 1) initialize virtual machine global state and configuration.
-    /// 2) create system devices, such as interrupt controller.
-    /// 3) create and start IO devices, such as serial, console, block, net, vsock etc.
-    /// 4) create and initialize vCPUs.
-    /// 5) configure CPU power management features.
-    /// 6) load guest kernel image.
+    /// 1) Initialize virtual machine reset event fd.
+    /// 2) Create and initialize vCPUs.
+    /// 3) Create and initialize interrupt controller.
+    /// 4) Create and initialize vPMU device.
+    /// 5) Create and initialize devices, such as virtio, block, net, vsock, vfio etc.
     pub fn init_microvm(
         &mut self,
         epoll_mgr: EpollManager,

src/dragonball/src/vm/mod.rs

@@ -860,6 +860,7 @@ impl Vm {
 
 #[cfg(test)]
 pub mod tests {
+    #[cfg(target_arch = "x86_64")]
     use kvm_ioctls::VcpuExit;
     use linux_loader::cmdline::Cmdline;
     use test_utils::skip_if_not_root;