main: Add kernel command line support

In order to let the user choose which kernel parameters to append, the
kernel boot parameters can be now specified from the command line.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

src/main.rs

@@ -25,6 +25,12 @@ fn main() {
                 .help("Path to kernel image (vmlinux)")
                 .takes_value(true),
         )
+        .arg(
+            Arg::with_name("cmdline")
+                .long("cmdline")
+                .help("Kernel command line")
+                .takes_value(true),
+        )
         .arg(
             Arg::with_name("disk")
                 .long("disk")
@@ -51,6 +57,11 @@ fn main() {
         .expect("Missing argument: kernel");
     let kernel_path = kernel_arg.as_path();
 
+    let cmdline = cmd_arguments
+        .value_of("cmdline")
+        .map(std::string::ToString::to_string)
+        .expect("Missing argument: cmdline");
+
     let disk_arg = cmd_arguments
         .value_of("disk")
         .map(PathBuf::from)
@@ -70,7 +81,7 @@ fn main() {
     println!("VM [{} vCPUS {} MB of memory]", vcpus, memory);
     println!("Booting {:?}...", kernel_path);
 
-    let vm_config = VmConfig::new(kernel_path, disk_path, vcpus, memory).unwrap();
+    let vm_config = VmConfig::new(kernel_path, disk_path, cmdline, vcpus, memory).unwrap();
 
     vmm::boot_kernel(vm_config).unwrap();
 }

vmm/src/vm.rs

@@ -40,8 +40,6 @@ use vmm_sys_util::EventFd;
 const VCPU_RTSIG_OFFSET: i32 = 0;
 pub const DEFAULT_VCPUS: u8 = 1;
 pub const DEFAULT_MEMORY: GuestUsize = 512;
-const DEFAULT_CMDLINE: &str = "console=ttyS0 reboot=k panic=1 nomodules \
-                               i8042.noaux i8042.nomux i8042.nopnp i8042.dumbkbd";
 const CMDLINE_OFFSET: GuestAddress = GuestAddress(0x20000);
 const X86_64_IRQ_BASE: u32 = 5;
 
@@ -207,7 +205,7 @@ impl Vcpu {
 pub struct VmConfig<'a> {
     kernel_path: &'a Path,
     disk_path: &'a Path,
-    cmdline: Option<cmdline::Cmdline>,
+    cmdline: cmdline::Cmdline,
     cmdline_addr: GuestAddress,
 
     memory_size: GuestUsize,
@@ -218,36 +216,24 @@ impl<'a> VmConfig<'a> {
     pub fn new(
         kernel_path: &'a Path,
         disk_path: &'a Path,
+        cmdline_str: String,
         vcpus: u8,
         memory_size: GuestUsize,
     ) -> Result<Self> {
+        let mut cmdline = cmdline::Cmdline::new(arch::CMDLINE_MAX_SIZE);
+        cmdline.insert_str(cmdline_str).unwrap();
+
         Ok(VmConfig {
             kernel_path,
             disk_path,
+            cmdline,
+            cmdline_addr: CMDLINE_OFFSET,
             memory_size,
             vcpu_count: vcpus,
-            ..Default::default()
         })
     }
 }
 
-impl<'a> Default for VmConfig<'a> {
-    fn default() -> Self {
-        let line = String::from(DEFAULT_CMDLINE);
-        let mut cmdline = cmdline::Cmdline::new(arch::CMDLINE_MAX_SIZE);
-        cmdline.insert_str(line).unwrap();
-
-        VmConfig {
-            kernel_path: Path::new(""),
-            disk_path: Path::new(""),
-            cmdline: Some(cmdline),
-            cmdline_addr: CMDLINE_OFFSET,
-            memory_size: DEFAULT_MEMORY,
-            vcpu_count: DEFAULT_VCPUS,
-        }
-    }
-}
-
 struct DeviceManager {
     io_bus: devices::Bus,
     mmio_bus: devices::Bus,
@@ -518,8 +504,8 @@ impl<'a> Vm<'a> {
     }
 
     pub fn load_kernel(&mut self) -> Result<GuestAddress> {
-        let cmdline = self.config.cmdline.clone().ok_or(Error::CmdLine)?;
+        let cmdline_cstring =
-        let cmdline_cstring = CString::new(cmdline).map_err(|_| Error::CmdLine)?;
+            CString::new(self.config.cmdline.clone()).map_err(|_| Error::CmdLine)?;
         let entry_addr = linux_loader::loader::Elf::load(
             &self.memory,
             None,