Add a --memory flag

src/main.rs

@@ -6,7 +6,7 @@ mod registry;
 use anyhow::Result;
 use clap::{Parser, Subcommand};
 
-use crate::image::ImageCmd;
+use crate::{image::ImageCmd, qemu::RunCmd};
 
 #[derive(Parser, Debug)]
 #[command(about = "Build bootable initrd VMs from container images")]
@@ -25,11 +25,8 @@ enum Commands {
         #[arg(short = 's', long, default_value = "512")]
         _size: String,
     },
-    /// Launch the VM via QEMU using registry artifacts
+    /// Launch a previously built VM via QEMU.
-    Run {
+    Run(RunCmd),
-        /// Image tag / registry subdir name
-        name: String,
-    },
     /// List slim images in the registry
     #[command(subcommand)]
     Image(ImageCmd),
@@ -41,8 +38,8 @@ fn main() -> Result<()> {
         Commands::Build { image, _size: _ } => {
             build::build(&image)?;
         }
-        Commands::Run { name } => {
+        Commands::Run(cmd) => {
-            qemu::run(&name)?;
+            qemu::run(cmd)?;
         }
         Commands::Image(cmd) => {
             image::run(cmd)?;

src/qemu.rs

@@ -2,12 +2,23 @@
 //! boot (-kernel/-initrd).
 
 use anyhow::{Context, Result, bail};
+use clap::Args;
 use std::process::Command;
 
 use crate::registry::registry_dir;
 
-pub(crate) fn run(name: &str) -> Result<()> {
+#[derive(Args, Debug)]
-    let reg_dir = registry_dir(name)?;
+pub struct RunCmd {
+    /// Image tag / registry subdir name
+    name: String,
+
+    /// Amount of memory to give the VM, in qemu's format.
+    #[clap(short, long, default_value = "1024M")]
+    memory: String,
+}
+
+pub(crate) fn run(RunCmd { name, memory }: RunCmd) -> Result<()> {
+    let reg_dir = registry_dir(&name)?;
     let vmlinuz_path = reg_dir.join("vmlinuz");
     let initrd_path = reg_dir.join("initrd");
     if !vmlinuz_path.exists() || !initrd_path.exists() {
@@ -16,7 +27,7 @@ pub(crate) fn run(name: &str) -> Result<()> {
             name
         );
     }
-    println!("Booting {} from registry: {}", name, reg_dir.display());
+    println!("Booting {name} from registry: {}", reg_dir.display());
     println!(
         "  qemu-system-x86_64 -m 256 -nographic -kernel {} -initrd {} -append 'console=ttyS0'",
         vmlinuz_path.display(),
@@ -35,7 +46,7 @@ pub(crate) fn run(name: &str) -> Result<()> {
 
     let mut command = Command::new("qemu-system-x86_64");
     command
-        .args(["-m", "1024M"])
+        .args(["-m", &memory])
         .arg("-kernel")
         .arg(vmlinuz_path.as_os_str())
         .arg("-initrd")