kernel: Allow kernel-specific cmdline snippets

These are vendor provided at source and shouldn't be disabled, as they're
intended for an exact kernel release. Right now the motivation is for out
of tree modules such as the nvidia proprietary driver, but this also allows
a kernel to ship its own cmdline file that cannot be overriden.

Signed-off-by: Ikey Doherty <[email protected]>

blsforme/src/bootloader/systemd_boot/mod.rs

@@ -167,7 +167,11 @@ impl<'a, 'b> Loader<'a, 'b> {
             format!("{} ({})", schema.os_release().name, entry.kernel.version)
         };
         let vmlinuz = entry.installed_kernel_name(schema).expect("linux go boom");
-        let options = "".to_owned() + cmdline;
+        let options = if let Some(k_cmdline) = entry.kernel.cmdline.as_ref() {
+            format!("{cmdline} {k_cmdline}")
+        } else {
+            cmdline.to_string()
+        };
         format!(
             r###"title {title}
 linux /EFI/{asset_dir}/{}{}

blsforme/src/kernel.rs

@@ -11,7 +11,7 @@ use std::{
 
 use serde::Deserialize;
 
-use crate::{os_release::OsRelease, Error};
+use crate::{file_utils::cmdline_snippet, os_release::OsRelease, Error};
 
 /// Control kernel discovery mechanism
 #[derive(Debug)]
@@ -70,6 +70,8 @@ pub struct Kernel {
 
     /// Recorded variant type
     pub variant: Option<String>,
+
+    pub cmdline: Option<String>,
 }
 
 /// Denotes the kind of auxiliary file
@@ -117,6 +119,24 @@ impl Schema<'_> {
         }
     }
 
+    fn load_cmdline(kernel: &Kernel) -> Result<String, Error> {
+        // Load local cmdline snippets for this kernel entry
+        let mut cmdline = String::new();
+        for snippet in kernel
+            .extras
+            .iter()
+            .filter(|e| matches!(e.kind, crate::AuxiliaryKind::Cmdline))
+        {
+            let snippet = cmdline_snippet(&snippet.path)?;
+            cmdline.push_str(&snippet);
+            cmdline.push(' ');
+        }
+
+        log::trace!("kernel-specific cmdline for {:?}: {cmdline}", kernel.image);
+
+        Ok(cmdline.trim().to_string())
+    }
+
     /// Discover any legacy kernels
     fn legacy_kernels(
         namespace: &'static str,
@@ -151,6 +171,7 @@ impl Schema<'_> {
                                 initrd: vec![],
                                 extras: vec![],
                                 variant: Some(variant.to_string()),
+                                cmdline: None,
                             },
                         );
                     }
@@ -245,6 +266,7 @@ impl Schema<'_> {
             kernel
                 .extras
                 .sort_by_key(|e| e.path.display().to_string().to_lowercase());
+            kernel.cmdline = Self::load_cmdline(kernel).ok().filter(|s| !s.is_empty());
         }
         Ok(kernels.into_values().collect::<Vec<_>>())
     }
@@ -267,6 +289,7 @@ impl Schema<'_> {
                         initrd: vec![],
                         extras: vec![],
                         variant: None,
+                        cmdline: None,
                     },
                 ))
             })
@@ -327,6 +350,7 @@ impl Schema<'_> {
                 kernel
                     .extras
                     .sort_by_key(|e| e.path.display().to_string().to_lowercase());
+                kernel.cmdline = Self::load_cmdline(kernel).ok().filter(|s| !s.is_empty());
             }
         }