Identify M.2 A/B and the boot disk from chassis labels

installinator/src/write.rs

@@ -122,10 +122,11 @@ impl WriteDestination {
         let mut drives = BTreeMap::new();
 
         for disk in hardware.m2_disks() {
-            let Ok(slot) = M2Slot::try_from(disk.pcie_slot()) else {
+            let Some(slot) = M2Slot::from_chassis_location(disk.location())
+            else {
                 warn!(
-                    log, "skipping M.2 drive with unexpected PCIe slot number";
-                    "pcie_slot" => disk.pcie_slot(),
+                    log, "skipping M.2 drive with unexpected chassis location";
+                    "location" => disk.location(),
                 );
                 continue;
             };

sled-agent/config-reconciler/src/internal_disks.rs

@@ -544,7 +544,7 @@ impl From<&'_ Disk> for InternalDiskDetails {
                 is_boot_disk: disk.is_boot_disk(),
             },
             zpool_id,
-            slot: M2Slot::try_from(disk.pcie_slot()).ok(),
+            slot: M2Slot::from_chassis_location(disk.location()),
             boot_image_raw_devfs_path: disk
                 .boot_image_devfs_path(true)
                 .map_err(Arc::new),

sled-agent/types/versions/src/impls/disk.rs

@@ -37,6 +37,19 @@ impl M2Slot {
             _ => None,
         }
     }
+
+    /// Look up the slot of an M.2 socket from its chassis label, returning
+    /// `None` for any other label.
+    ///
+    /// Gimlet and Cosmo both pair M.2 East with boot storage unit A and
+    /// M.2 West with B.
+    pub fn from_chassis_location(location: &str) -> Option<Self> {
+        match location {
+            "M.2 East" => Some(Self::A),
+            "M.2 West" => Some(Self::B),
+            _ => None,
+        }
+    }
 }
 
 impl fmt::Display for M2Slot {
@@ -63,21 +76,6 @@ impl FromStr for M2Slot {
     }
 }
 
-impl TryFrom<i64> for M2Slot {
-    type Error = anyhow::Error;
-
-    fn try_from(value: i64) -> Result<Self, Self::Error> {
-        match value {
-            // Gimlet and Cosmo have two M.2 drives. The value here is the
-            // PCIe physical slot number of the bridge above the drive:
-            // drive A is behind slot 0x11 and drive B behind slot 0x12.
-            17 => Ok(Self::A),
-            18 => Ok(Self::B),
-            _ => bail!("unexpected M.2 slot {value}"),
-        }
-    }
-}
-
 impl From<ZpoolKind> for DiskVariant {
     fn from(kind: ZpoolKind) -> DiskVariant {
         match kind {
@@ -152,3 +150,16 @@ impl FromStr for CompressionAlgorithm {
         Ok(c)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn m2_slot_from_chassis_location() {
+        assert_eq!(M2Slot::from_chassis_location("M.2 East"), Some(M2Slot::A));
+        assert_eq!(M2Slot::from_chassis_location("M.2 West"), Some(M2Slot::B));
+        assert_eq!(M2Slot::from_chassis_location("N0"), None);
+        assert_eq!(M2Slot::from_chassis_location("M.2 2"), None);
+    }
+}