diff --git a/src/cpu/kernel/assembler.rs b/src/cpu/kernel/assembler.rs
new file mode 100644
index 00000000..1fc3185a
--- /dev/null
+++ b/src/cpu/kernel/assembler.rs
@@ -0,0 +1,6 @@
+use crate::cpu::generation::MipsTrace;
+#[derive(PartialEq, Eq, Debug, Serialize, Deserialize)]
+pub struct Kernel {
+    pub(crate) code: Vec<u8>,
+}
+
diff --git a/src/generation/state.rs b/src/generation/state.rs
new file mode 100644
index 00000000..3daae3c7
--- /dev/null
+++ b/src/generation/state.rs
@@ -0,0 +1,21 @@
+use std::collections::HashMap;
+
+use ethereum_types::{Address, BigEndianHash, H160, H256, U256};
+use keccak_hash::keccak;
+use plonky2::field::types::Field;
+
+use crate::cpu::kernel::aggregator::KERNEL;
+use crate::cpu::kernel::constants::context_metadata::ContextMetadata;
+use crate::generation::mpt::all_mpt_prover_inputs_reversed;
+use crate::generation::rlp::all_rlp_prover_inputs_reversed;
+use crate::generation::GenerationInputs;
+use crate::memory::segments::Segment;
+use crate::witness::errors::ProgramError;
+use crate::witness::memory::{MemoryAddress, MemoryState};
+use crate::witness::state::RegistersState;
+use crate::witness::traces::{TraceCheckpoint, Traces};
+
+pub(crate) struct GenerationState {
+    pub(crate) inputs: GenerationInputs,
+    pub(crate) traces: Traces<F>,
+}
diff --git a/src/witness/state.rs b/src/witness/state.rs
new file mode 100644
index 00000000..5331dc5d
--- /dev/null
+++ b/src/witness/state.rs
@@ -0,0 +1,31 @@
+use crate::cpu::kernel::aggregator::KERNEL;
+
+const KERNEL_CONTEXT: usize = 0;
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct RegistersState {
+    pub program_counter: usize,
+    pub is_kernel: bool,
+    pub context: usize,
+}
+
+impl RegistersState {
+    pub(crate) fn code_context(&self) -> usize {
+        if self.is_kernel {
+            KERNEL_CONTEXT
+        } else {
+            self.context
+        }
+    }
+}
+
+impl Default for RegistersState {
+    fn default() -> Self {
+        Self {
+            // FIXME: fill in pc
+            program_counter: 0,
+            is_kernel: true,
+            context: 0,
+        }
+    }
+}