feat: collect LLDP data on DPU and host (1/3)

crates/agent/src/command_line.rs

@@ -58,6 +58,9 @@ pub enum AgentCommand {
     #[clap(about = "One-off health check")]
     Health,
 
+    #[clap(about = "Print LLDP neighbors visible on this host and exit")]
+    LldpNeighbors,
+
     #[clap(about = "One-off network monitor")]
     Network(NetworkOptions),
 

crates/agent/src/lib.rs

@@ -226,6 +226,10 @@ pub async fn start(cmdline: command_line::Options) -> eyre::Result<()> {
             println!("{}", serde_json::to_string_pretty(&health_report)?);
         }
 
+        Some(AgentCommand::LldpNeighbors) => {
+            carbide_host_support::lldp_collector::print_lldp_neighbors()?;
+        }
+
         // One-off network monitor check.
         // dumps JSON-formatted peer DPU network reachability and latency status
         Some(AgentCommand::Network(options)) => {

crates/agent/src/main.rs

@@ -18,6 +18,13 @@
 use std::time::Duration;
 
 fn main() -> eyre::Result<()> {
+    let options = agent::Options::load();
+
+    // Purely local interrogation for troubleshooting.
+    if matches!(options.cmd, Some(agent::AgentCommand::LldpNeighbors)) {
+        return carbide_host_support::lldp_collector::print_lldp_neighbors();
+    }
+
     carbide_host_support::init_logging("nico-dpu-agent")?;
 
     // We need a multi-threaded runtime since background threads will queue work
@@ -26,7 +33,7 @@ fn main() -> eyre::Result<()> {
     let rt = tokio::runtime::Builder::new_multi_thread()
         .enable_all()
         .build()?;
-    rt.block_on(agent::start(agent::Options::load()))?;
+    rt.block_on(agent::start(options))?;
     rt.shutdown_timeout(Duration::from_secs(2));
     Ok(())
 }

crates/host-support/src/hardware_enumeration.rs

@@ -42,7 +42,7 @@ mod tpm;
 /// Path where the init container writes the hardware snapshot, and the containerized agent reads it from.
 pub const HW_CACHE_PATH: &str = "/data/hw_output.json";
 
-const PCI_SUBCLASS: &str = "ID_PCI_SUBCLASS_FROM_DATABASE";
+pub(crate) const PCI_SUBCLASS: &str = "ID_PCI_SUBCLASS_FROM_DATABASE";
 const PCI_DEV_PATH: &str = "DEVPATH";
 const PCI_MODEL: &str = "ID_MODEL_FROM_DATABASE";
 const PCI_SLOT_NAME: &str = "PCI_SLOT_NAME";
@@ -154,7 +154,7 @@ fn convert_udev_to_mac(udev: String) -> Result<String, HardwareEnumerationError>
     Ok(mac)
 }
 
-fn convert_property_to_string<'a>(
+pub fn convert_property_to_string<'a>(
     name: &'a str,
     default_value: &'a str,
     device: &'a Device,