diff --git a/src/arch/aarch64.rs b/src/arch/aarch64.rs
new file mode 100644
index 00000000..9f8bfed0
--- /dev/null
+++ b/src/arch/aarch64.rs
@@ -0,0 +1,9 @@
+#[allow(missing_docs)]
+#[derive(Clone, Debug)]
+#[repr(C)]
+pub struct SavedFrame {
+    pub gp_regs: [u64; 32],
+    pub spsr_el1: u64,
+    pub elr_el1: u64,
+    pub sp_el0: u64,
+}
diff --git a/src/arch/mod.rs b/src/arch/mod.rs
new file mode 100644
index 00000000..57a6ad25
--- /dev/null
+++ b/src/arch/mod.rs
@@ -0,0 +1,13 @@
+//! Architecture-specific ABI implementation details
+
+#[cfg(target_arch = "aarch64")]
+pub(crate) mod aarch64;
+#[cfg(target_arch = "aarch64")]
+use aarch64 as arch_impl;
+
+#[cfg(target_arch = "x86_64")]
+pub(crate) mod x86_64;
+#[cfg(target_arch = "x86_64")]
+use x86_64 as arch_impl;
+
+pub use arch_impl::SavedFrame;
diff --git a/src/arch/x86_64.rs b/src/arch/x86_64.rs
new file mode 100644
index 00000000..40a9b039
--- /dev/null
+++ b/src/arch/x86_64.rs
@@ -0,0 +1,26 @@
+#![allow(missing_docs)]
+
+#[derive(Clone, Debug)]
+#[repr(C)]
+pub struct SavedFrame {
+    pub rax: u64,
+    pub rcx: u64,
+    pub rdx: u64,
+    pub rbx: u64,
+    pub rsi: u64,
+    pub rdi: u64,
+    pub rbp: u64,
+
+    pub r8: u64,
+    pub r9: u64,
+    pub r10: u64,
+    pub r11: u64,
+    pub r12: u64,
+    pub r13: u64,
+    pub r14: u64,
+    pub r15: u64,
+
+    pub user_ip: u64,
+    pub user_sp: u64,
+    pub rflags: u64,
+}
diff --git a/src/error.rs b/src/error.rs
index 96e3b49a..1f17c785 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -28,6 +28,8 @@ primitive_enum!(
         DirectoryNotEmpty = 11,
         #[doc = "Operation was interrupted"]
         Interrupted = 12,
+        #[doc = "Operation has not completed yet"]
+        WouldBlock = 13,
     }
 );
 
diff --git a/src/lib.rs b/src/lib.rs
index d52970dc..984e5b3f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,7 @@
 
 pub(crate) mod macros;
 
+pub mod arch;
 pub mod error;
 pub mod io;
 pub mod path;
diff --git a/src/macros.rs b/src/macros.rs
index 75521902..5006cc81 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -1,15 +1,15 @@
 /// Helper macro to define primitive enums with integer reprs, as well as their conversion methods
 #[macro_export]
 macro_rules! primitive_enum {
-    ($(#[doc = $enum_doc:expr])? $vis:vis enum $name:ident: $repr:ty {
-        $( $(#[doc = $doc:expr])? $variant:ident = $discriminant:literal, )+
+    ($(#[$struct_meta:meta])* $vis:vis enum $name:ident: $repr:ty {
+        $( $(#[$variant_meta:meta])* $variant:ident = $discriminant:literal, )+
     }) => {
         #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
         #[repr($repr)]
-        $(#[doc = $enum_doc])?
+        $(#[$struct_meta])*
         $vis enum $name {
             $(
-                $(#[doc = $doc])?
+                $(#[$variant_meta])?
                 $variant = $discriminant
             ),+
         }
diff --git a/src/process.rs b/src/process.rs
index 6d9623d9..503eb1c3 100644
--- a/src/process.rs
+++ b/src/process.rs
@@ -2,7 +2,7 @@
 
 use core::num::NonZeroI32;
 
-use crate::{io::RawFd, primitive_enum};
+use crate::{arch::SavedFrame, io::RawFd, primitive_enum};
 
 /// Code signalled by a process when it finishes or is terminated by a signal
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -40,21 +40,6 @@ primitive_enum! {
     }
 }
 
-/// Platform-specific "snapshot" of a program's context, used to restore it later when returning
-/// from a signal handler
-#[derive(Clone, Debug)]
-#[repr(C)]
-pub struct SavedFrame {
-    /// General-purpose registers
-    pub gp_regs: [u64; 32],
-    /// SPSR_EL1
-    pub spsr_el1: u64,
-    /// ELR_EL1 (return address)
-    pub elr_el1: u64,
-    /// SP_EL0 (return stack)
-    pub sp_el0: u64,
-}
-
 /// Data provided by the kernel to signal entry function
 #[derive(Clone, Debug)]
 #[repr(C)]