diff --git a/crates/rugpi-bakery/src/bake/mod.rs b/crates/rugpi-bakery/src/bake/mod.rs
index f13fd47..b9c7278 100644
--- a/crates/rugpi-bakery/src/bake/mod.rs
+++ b/crates/rugpi-bakery/src/bake/mod.rs
@@ -32,7 +32,9 @@ pub fn bake_layer(project: &Project, arch: Architecture, layer: &str) -> Anyhow<
     let library = project.load_library()?;
     let layer_config = &library.layers[library
         .lookup_layer(library.repositories.root_repository, layer)
-        .unwrap()];
+        .unwrap()]
+    .config(arch)
+    .unwrap();
     if let Some(url) = &layer_config.url {
         let layer_id = sha1(url);
         let system_tar = project
diff --git a/crates/rugpi-bakery/src/project/config.rs b/crates/rugpi-bakery/src/project/config.rs
index 9628e0e..b3c29f4 100644
--- a/crates/rugpi-bakery/src/project/config.rs
+++ b/crates/rugpi-bakery/src/project/config.rs
@@ -1,11 +1,12 @@
 //! Project configuration.
 
-use std::{collections::HashMap, fs, path::Path};
+use std::{collections::HashMap, fs, path::Path, str::FromStr};
 
 use anyhow::Context;
 use clap::ValueEnum;
 use rugpi_common::Anyhow;
 use serde::{Deserialize, Serialize};
+use thiserror::Error;
 
 use super::{images::ImageConfig, repositories::Source};
 
@@ -40,7 +41,7 @@ pub enum IncludeFirmware {
     Pi5,
 }
 
-#[derive(Debug, Clone, Copy, Serialize, Deserialize, Default, ValueEnum)]
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, Default, PartialEq, Eq, Hash, ValueEnum)]
 #[clap(rename_all = "lowercase")]
 #[serde(rename_all = "lowercase")]
 pub enum Architecture {
@@ -49,6 +50,22 @@ pub enum Architecture {
     Armhf,
 }
 
+#[derive(Debug, Error)]
+#[error("invalid architecture")]
+pub struct InvalidArchitectureError;
+
+impl FromStr for Architecture {
+    type Err = InvalidArchitectureError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "arm64" => Ok(Self::Arm64),
+            "armhf" => Ok(Self::Armhf),
+            _ => Err(InvalidArchitectureError),
+        }
+    }
+}
+
 impl Architecture {
     pub fn as_str(self) -> &'static str {
         match self {
diff --git a/crates/rugpi-bakery/src/project/layers.rs b/crates/rugpi-bakery/src/project/layers.rs
index 48b45da..61862a4 100644
--- a/crates/rugpi-bakery/src/project/layers.rs
+++ b/crates/rugpi-bakery/src/project/layers.rs
@@ -8,11 +8,16 @@ use anyhow::Context;
 use rugpi_common::Anyhow;
 use serde::{Deserialize, Serialize};
 
-use super::recipes::{ParameterValue, RecipeName};
+use super::{
+    config::Architecture,
+    recipes::{ParameterValue, RecipeName},
+};
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct LayerConfig {
+    /// Optional human-readable name of the layer.
+    pub name: Option<String>,
     /// An URL to fetch the layer from.
     pub url: Option<String>,
     pub parent: Option<String>,
@@ -36,3 +41,18 @@ impl LayerConfig {
         .with_context(|| format!("error parsing layer config from path `{path:?}`"))
     }
 }
+
+#[derive(Debug, Default)]
+pub struct Layer {
+    pub default_config: Option<LayerConfig>,
+    pub arch_configs: HashMap<Architecture, LayerConfig>,
+}
+
+impl Layer {
+    /// The layer configuration for the given architecture.
+    pub fn config(&self, arch: Architecture) -> Option<&LayerConfig> {
+        self.arch_configs
+            .get(&arch)
+            .or(self.default_config.as_ref())
+    }
+}
diff --git a/crates/rugpi-bakery/src/project/library.rs b/crates/rugpi-bakery/src/project/library.rs
index b298e28..23adb0a 100644
--- a/crates/rugpi-bakery/src/project/library.rs
+++ b/crates/rugpi-bakery/src/project/library.rs
@@ -1,9 +1,10 @@
-use std::{collections::HashMap, fs, ops::Deref, sync::Arc};
+use std::{collections::HashMap, fs, ops::Deref, str::FromStr, sync::Arc};
 
 use rugpi_common::Anyhow;
 
 use super::{
-    layers::LayerConfig,
+    config::Architecture,
+    layers::{Layer, LayerConfig},
     recipes::{Recipe, RecipeLoader},
     repositories::{ProjectRepositories, RepositoryIdx},
 };
@@ -12,7 +13,7 @@ use crate::idx_vec::{new_idx_type, IdxVec};
 pub struct Library {
     pub repositories: ProjectRepositories,
     pub recipes: IdxVec<RecipeIdx, Arc<Recipe>>,
-    pub layers: IdxVec<LayerIdx, LayerConfig>,
+    pub layers: IdxVec<LayerIdx, Layer>,
     pub recipe_tables: IdxVec<RepositoryIdx, HashMap<String, RecipeIdx>>,
     pub layer_tables: IdxVec<RepositoryIdx, HashMap<String, LayerIdx>>,
 }
@@ -52,10 +53,24 @@ impl Library {
                     for entry in fs::read_dir(layers_dir)? {
                         let entry = entry?;
                         let path = entry.path();
-                        let layer_name = path.file_stem().unwrap();
+                        let mut name = path.file_stem().unwrap().to_string_lossy().into_owned();
+                        let mut arch = None;
+                        if let Some((layer_name, arch_str)) = name.split_once('.') {
+                            arch = Some(Architecture::from_str(arch_str)?);
+                            name = layer_name.to_owned();
+                        }
                         let layer_config = LayerConfig::load(&path)?;
-                        let layer_idx = layers.push(layer_config);
-                        table.insert(layer_name.to_string_lossy().into_owned(), layer_idx);
+                        let layer_idx = *table
+                            .entry(name)
+                            .or_insert_with(|| layers.push(Layer::default()));
+                        match arch {
+                            Some(arch) => {
+                                layers[layer_idx].arch_configs.insert(arch, layer_config);
+                            }
+                            None => {
+                                layers[layer_idx].default_config = Some(layer_config);
+                            }
+                        }
                     }
                     Ok(table)
                 })
diff --git a/repositories/core/layers/raspios-bookworm.arm64.toml b/repositories/core/layers/raspios-bookworm.arm64.toml
new file mode 100644
index 0000000..1d28e00
--- /dev/null
+++ b/repositories/core/layers/raspios-bookworm.arm64.toml
@@ -0,0 +1,2 @@
+name = "Raspberry Pi OS (Bookworm)"
+url = "https://downloads.raspberrypi.com/raspios_lite_arm64/images/raspios_lite_arm64-2023-12-11/2023-12-11-raspios-bookworm-arm64-lite.img.xz"
\ No newline at end of file
diff --git a/repositories/core/layers/raspios-bookworm.armhf.toml b/repositories/core/layers/raspios-bookworm.armhf.toml
new file mode 100644
index 0000000..e3cbf0b
--- /dev/null
+++ b/repositories/core/layers/raspios-bookworm.armhf.toml
@@ -0,0 +1,2 @@
+name = "Raspberry Pi OS (Bookworm)"
+url = "https://downloads.raspberrypi.com/raspios_lite_armhf/images/raspios_lite_armhf-2023-12-11/2023-12-11-raspios-bookworm-armhf-lite.img.xz"
\ No newline at end of file
diff --git a/repositories/core/layers/raspios-bullseye.arm64.toml b/repositories/core/layers/raspios-bullseye.arm64.toml
new file mode 100644
index 0000000..166ff12
--- /dev/null
+++ b/repositories/core/layers/raspios-bullseye.arm64.toml
@@ -0,0 +1,2 @@
+name = "Raspberry Pi OS (Bullseye)"
+url = "https://downloads.raspberrypi.com/raspios_oldstable_lite_arm64/images/raspios_oldstable_lite_arm64-2023-12-06/2023-12-05-raspios-bullseye-arm64-lite.img.xz"
\ No newline at end of file
diff --git a/repositories/core/layers/raspios-bullseye.armhf.toml b/repositories/core/layers/raspios-bullseye.armhf.toml
new file mode 100644
index 0000000..5ad6d8a
--- /dev/null
+++ b/repositories/core/layers/raspios-bullseye.armhf.toml
@@ -0,0 +1,2 @@
+name = "Raspberry Pi OS (Bullseye)"
+url = "https://downloads.raspberrypi.com/raspios_oldstable_lite_armhf/images/raspios_oldstable_lite_armhf-2023-12-06/2023-12-05-raspios-bullseye-armhf-lite.img.xz"
\ No newline at end of file
diff --git a/template b/template
index 929a30d..a63c081 160000
--- a/template
+++ b/template
@@ -1 +1 @@
-Subproject commit 929a30d7c28c6e9878790c9de7c2280acde14a30
+Subproject commit a63c081d0f5ed6b54e2213b51dbab7be90135336