bootstrap:

Cargo.lock

@@ -247,6 +247,7 @@ dependencies = [
  "serde_json",
  "serde_yaml",
  "shell-escape",
+ "sys-info",
  "termios",
  "tokio",
  "unix_mode",
@@ -577,6 +578,16 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "sys-info"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b3a0d0aba8bf96a0e1ddfdc352fc53b3df7f39318c71854910c3c4b024ae52c"
+dependencies = [
+ "cc",
+ "libc",
+]
+
 [[package]]
 name = "termios"
 version = "0.3.3"

Cargo.toml

@@ -29,3 +29,4 @@ unix_mode = "0.1.4"
 cpio = "0.4.1"
 lz4 = "1.28.1"
 base64 = "0.22.1"
+sys-info = "0.9.1"

src/cmd/init/bootstrap.rs

@@ -1,5 +1,5 @@
 use eyre::{format_err, Result};
-use log::info;
+use log::{info, warn};
 use std::path::Path;
 use tokio::{
     fs,
@@ -20,7 +20,7 @@ pub async fn bootstrap(cfg: Config) {
     })
     .await;
 
-    let boot_version = utils::param("version", "current");
+    let boot_version = utils::param("version").unwrap_or("current");
     let base_dir = &format!("/bootstrap/{boot_version}");
 
     retry_or_ignore(async || {
@@ -169,9 +169,25 @@ async fn fetch_bootstrap(seed_url: &str, output_file: &str) -> Result<()> {
     Ok(())
 }
 
+fn default_root_tmpfs_opts() -> Option<String> {
+    let mem = sys_info::mem_info()
+        .inspect_err(|e| warn!("failed to get system memory info, using default tmpfs size: {e}"))
+        .ok()?;
+
+    let mem_size = mem.total /* kiB */ / 1024;
+    let fs_size = 1024.min(mem_size / 2);
+    info!("system has {mem_size} MiB of memory, allowing {fs_size} MiB for root tmpfs");
+    Some(format!("size={fs_size}m"))
+}
+
 async fn mount_system(cfg: &dkl::Config, bs_dir: &str, verifier: &Verifier) {
+    let opts = match utils::param("root-opts") {
+        Some(s) => Some(s.to_string()),
+        None => default_root_tmpfs_opts(),
+    };
+
     let mem_dir = "/mem";
-    mount(None, mem_dir, "tmpfs", Some("size=512m")).await;
+    mount(None, mem_dir, "tmpfs", opts.as_deref()).await;
 
     let layers_dir = &format!("{mem_dir}/layers");
     let mut lower_dir = String::new();
@@ -316,14 +332,10 @@ async fn mount_filesystems(mounts: &[dkl::Mount], root: &str) {
         mount(
             Some(&m.dev),
             &path,
-            m.r#type
+            (m.r#type.as_deref())
-                .as_ref()
                 .filter(|s| !s.is_empty())
-                .map_or("ext4", |s| s.as_str()),
+                .unwrap_or("ext4"),
-            m.options
+            m.options.as_deref().filter(|v| !v.is_empty()),
-                .as_ref()
-                .filter(|v| !v.is_empty())
-                .map(|s| s.as_str()),
         )
         .await;
     }

src/main.rs

@@ -11,8 +11,9 @@ async fn main() -> Result<()> {
 
     dklog::init();
 
-    let call_name = env::args().next().unwrap_or("init".into());
+    let call_name = env::args().next();
-    let call_name = (call_name.rsplit_once('/').map(|(_, n)| n)).unwrap_or(call_name.as_str());
+    let call_name = call_name.as_deref().unwrap_or("init");
+    let call_name = call_name.rsplit_once('/').map_or(call_name, |(_, n)| n);
 
     let result = match call_name {
         "init" => {

src/utils.rs

@@ -20,16 +20,14 @@ pub fn bool_param(name: &str) -> bool {
     cmdline().any(|part| part == name1 || part == name2)
 }
 
-pub fn param<'t>(name: &'t str, default: &'t str) -> &'t str {
+pub fn param(name: &str) -> Option<&'static str> {
     let prefix1 = &format!("dkl.{name}=");
     let prefix2 = &format!("direktil.{name}=");
 
-    cmdline()
+    cmdline().find_map(|part| {
-        .find_map(|part| {
         part.strip_prefix(prefix1)
             .or_else(|| part.strip_prefix(prefix2))
     })
-        .unwrap_or(default)
 }
 
 pub struct NameAliases {