diff --git a/define-syscall/src/definitions.rs b/define-syscall/src/definitions.rs
index 76e91df5c..da614c6e0 100644
--- a/define-syscall/src/definitions.rs
+++ b/define-syscall/src/definitions.rs
@@ -49,12 +49,12 @@ define_syscall!(fn sol_get_return_data(data: *mut u8, length: u64, program_id: *
 // - `is_writable` (`u8`): `true` if the instruction requires the account to be writable
 define_syscall!(fn sol_get_processed_sibling_instruction(index: u64, meta: *mut u8, program_id: *mut u8, data: *mut u8, accounts: *mut u8) -> u64);
 
-// these are to be deprecated once they are superceded by sol_get_sysvar
-define_syscall!(fn sol_get_clock_sysvar(addr: *mut u8) -> u64);
-define_syscall!(fn sol_get_epoch_schedule_sysvar(addr: *mut u8) -> u64);
-define_syscall!(fn sol_get_rent_sysvar(addr: *mut u8) -> u64);
-define_syscall!(fn sol_get_last_restart_slot(addr: *mut u8) -> u64);
-define_syscall!(fn sol_get_epoch_rewards_sysvar(addr: *mut u8) -> u64);
+// these are deprecated - use sol_get_sysvar instead
+define_syscall!(#[deprecated(since = "4.1.0", note = "Use `sol_get_sysvar` with `Clock` sysvar address instead")] fn sol_get_clock_sysvar(addr: *mut u8) -> u64);
+define_syscall!(#[deprecated(since = "4.1.0", note = "Use `sol_get_sysvar` with `EpochSchedule` sysvar address instead")] fn sol_get_epoch_schedule_sysvar(addr: *mut u8) -> u64);
+define_syscall!(#[deprecated(since = "4.1.0", note = "Use `sol_get_sysvar` with `Rent` sysvar address instead")] fn sol_get_rent_sysvar(addr: *mut u8) -> u64);
+define_syscall!(#[deprecated(since = "4.1.0", note = "Use `sol_get_sysvar` with `LastRestartSlot` sysvar address instead")] fn sol_get_last_restart_slot(addr: *mut u8) -> u64);
+define_syscall!(#[deprecated(since = "4.1.0", note = "Use `sol_get_sysvar` with `EpochRewards` sysvar address instead")] fn sol_get_epoch_rewards_sysvar(addr: *mut u8) -> u64);
 
 // this cannot go through sol_get_sysvar but can be removed once no longer in use
 define_syscall!(fn sol_get_fees_sysvar(addr: *mut u8) -> u64);
diff --git a/define-syscall/src/lib.rs b/define-syscall/src/lib.rs
index 47f8e5ea6..3d8e956c9 100644
--- a/define-syscall/src/lib.rs
+++ b/define-syscall/src/lib.rs
@@ -9,7 +9,8 @@ pub mod definitions;
 ))]
 #[macro_export]
 macro_rules! define_syscall {
-    (fn $name:ident($($arg:ident: $typ:ty),*) -> $ret:ty) => {
+    ($(#[$attr:meta])* fn $name:ident($($arg:ident: $typ:ty),*) -> $ret:ty) => {
+        $(#[$attr])*
         #[inline]
         pub unsafe fn $name($($arg: $typ),*) -> $ret {
             // this enum is used to force the hash to be computed in a const context
@@ -23,8 +24,8 @@ macro_rules! define_syscall {
         }
 
     };
-    (fn $name:ident($($arg:ident: $typ:ty),*)) => {
-        define_syscall!(fn $name($($arg: $typ),*) -> ());
+    ($(#[$attr:meta])* fn $name:ident($($arg:ident: $typ:ty),*)) => {
+        define_syscall!($(#[$attr])* fn $name($($arg: $typ),*) -> ());
     }
 }
 
@@ -34,13 +35,14 @@ macro_rules! define_syscall {
 )))]
 #[macro_export]
 macro_rules! define_syscall {
-    (fn $name:ident($($arg:ident: $typ:ty),*) -> $ret:ty) => {
+    ($(#[$attr:meta])* fn $name:ident($($arg:ident: $typ:ty),*) -> $ret:ty) => {
         extern "C" {
+            $(#[$attr])*
             pub fn $name($($arg: $typ),*) -> $ret;
         }
     };
-    (fn $name:ident($($arg:ident: $typ:ty),*)) => {
-        define_syscall!(fn $name($($arg: $typ),*) -> ());
+    ($(#[$attr:meta])* fn $name:ident($($arg:ident: $typ:ty),*)) => {
+        define_syscall!($(#[$attr])* fn $name($($arg: $typ),*) -> ());
     }
 }
 
diff --git a/epoch-rewards/src/lib.rs b/epoch-rewards/src/lib.rs
index 5d581891a..c7ea303c8 100644
--- a/epoch-rewards/src/lib.rs
+++ b/epoch-rewards/src/lib.rs
@@ -51,6 +51,9 @@ pub struct EpochRewards {
 
     /// Whether the rewards period (including calculation and distribution) is
     /// active
+    ///
+    /// SAFETY: upstream invariant: the sysvar data is created exclusively
+    /// by the Solana runtime and serializes bool as 0x00 or 0x01.
     pub active: bool,
 }
 
diff --git a/sysvar/src/clock.rs b/sysvar/src/clock.rs
index bde88bab2..dadb6335f 100644
--- a/sysvar/src/clock.rs
+++ b/sysvar/src/clock.rs
@@ -130,8 +130,64 @@ pub use {
 };
 
 impl Sysvar for Clock {
-    impl_sysvar_get!(sol_get_clock_sysvar);
+    impl_sysvar_get!(id());
 }
 
 #[cfg(feature = "bincode")]
 impl SysvarSerialize for Clock {}
+
+#[cfg(test)]
+mod tests {
+    use {super::*, crate::tests::to_bytes, serial_test::serial};
+
+    #[test]
+    #[cfg(feature = "bincode")]
+    fn test_clock_size_matches_bincode() {
+        // Prove that Clock's in-memory layout matches its bincode serialization.
+        let clock = Clock::default();
+        let in_memory_size = core::mem::size_of::<Clock>();
+        let bincode_size = bincode::serialized_size(&clock).unwrap() as usize;
+
+        assert_eq!(
+            in_memory_size, bincode_size,
+            "Clock in-memory size ({in_memory_size}) must match bincode size ({bincode_size})",
+        );
+    }
+
+    #[test]
+    #[serial]
+    fn test_clock_get_uses_sysvar_syscall() {
+        let expected = Clock {
+            slot: 1,
+            epoch_start_timestamp: 2,
+            epoch: 3,
+            leader_schedule_epoch: 4,
+            unix_timestamp: 5,
+        };
+
+        let data = to_bytes(&expected);
+        crate::tests::mock_get_sysvar_syscall(&data);
+
+        let got = Clock::get().unwrap();
+        assert_eq!(got, expected);
+    }
+
+    #[test]
+    #[serial]
+    fn test_clock_get_passes_correct_sysvar_id() {
+        let expected = Clock {
+            slot: 11,
+            epoch_start_timestamp: 22,
+            epoch: 33,
+            leader_schedule_epoch: 44,
+            unix_timestamp: 55,
+        };
+        let data = to_bytes(&expected);
+        let prev = crate::tests::mock_get_sysvar_syscall_with_id(&data, &id());
+
+        let got = Clock::get().unwrap();
+        assert_eq!(got, expected);
+
+        let _ = crate::program_stubs::set_syscall_stubs(prev);
+    }
+}
diff --git a/sysvar/src/epoch_rewards.rs b/sysvar/src/epoch_rewards.rs
index ae741e4ef..3e87254e9 100755
--- a/sysvar/src/epoch_rewards.rs
+++ b/sysvar/src/epoch_rewards.rs
@@ -163,8 +163,39 @@ pub use {
 };
 
 impl Sysvar for EpochRewards {
-    impl_sysvar_get!(sol_get_epoch_rewards_sysvar);
+    // SAFETY: upstream invariant: the sysvar data is created exclusively
+    // by the Solana runtime and serializes bool as 0x00 or 0x01, so the final
+    // `bool` field of `EpochRewards` can be re-aligned with padding and read
+    // directly without validation.
+    impl_sysvar_get!(id(), 15);
 }
 
 #[cfg(feature = "bincode")]
 impl SysvarSerialize for EpochRewards {}
+
+#[cfg(test)]
+mod tests {
+    use {super::*, crate::Sysvar, serial_test::serial};
+
+    #[test]
+    #[serial]
+    #[cfg(feature = "bincode")]
+    fn test_epoch_rewards_get() {
+        let expected = EpochRewards {
+            distribution_starting_block_height: 42,
+            num_partitions: 7,
+            parent_blockhash: solana_hash::Hash::new_unique(),
+            total_points: 1234567890,
+            total_rewards: 100,
+            distributed_rewards: 10,
+            active: true,
+        };
+
+        let data = bincode::serialize(&expected).unwrap();
+        assert_eq!(data.len(), 81);
+
+        crate::tests::mock_get_sysvar_syscall(&data);
+        let got = EpochRewards::get().unwrap();
+        assert_eq!(got, expected);
+    }
+}
diff --git a/sysvar/src/epoch_schedule.rs b/sysvar/src/epoch_schedule.rs
index d189434a3..2dca37de5 100644
--- a/sysvar/src/epoch_schedule.rs
+++ b/sysvar/src/epoch_schedule.rs
@@ -119,17 +119,126 @@
 //! #
 //! # Ok::<(), anyhow::Error>(())
 //! ```
+use crate::Sysvar;
 #[cfg(feature = "bincode")]
 use crate::SysvarSerialize;
-use crate::{impl_sysvar_get, Sysvar};
 pub use {
     solana_epoch_schedule::EpochSchedule,
     solana_sdk_ids::sysvar::epoch_schedule::{check_id, id, ID},
 };
 
+/// Pod (Plain Old Data) representation of [`EpochSchedule`] with no padding.
+///
+/// This type can be safely loaded via `sol_get_sysvar` without undefined behavior.
+/// Provides performant zero-copy accessors as an alternative to the `EpochSchedule` type.
+#[repr(C)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct PodEpochSchedule {
+    slots_per_epoch: [u8; 8],
+    leader_schedule_slot_offset: [u8; 8],
+    warmup: u8,
+    first_normal_epoch: [u8; 8],
+    first_normal_slot: [u8; 8],
+}
+
+const POD_EPOCH_SCHEDULE_SIZE: usize = 33;
+const _: () = assert!(core::mem::size_of::<PodEpochSchedule>() == POD_EPOCH_SCHEDULE_SIZE);
+
+impl PodEpochSchedule {
+    /// Fetch the sysvar data using the `sol_get_sysvar` syscall.
+    /// This provides an alternative to `EpochSchedule` which provides zero-copy accessors.
+    pub fn fetch() -> Result<Self, solana_program_error::ProgramError> {
+        let mut pod = core::mem::MaybeUninit::<Self>::uninit();
+        // Safety: `get_sysvar_unchecked` will initialize `pod` with the sysvar data,
+        // and error if unsuccessful.
+        unsafe {
+            crate::get_sysvar_unchecked(
+                pod.as_mut_ptr() as *mut u8,
+                (&id()) as *const _ as *const u8,
+                0,
+                POD_EPOCH_SCHEDULE_SIZE as u64,
+            )?;
+            Ok(pod.assume_init())
+        }
+    }
+
+    pub fn slots_per_epoch(&self) -> u64 {
+        u64::from_le_bytes(self.slots_per_epoch)
+    }
+
+    pub fn leader_schedule_slot_offset(&self) -> u64 {
+        u64::from_le_bytes(self.leader_schedule_slot_offset)
+    }
+
+    pub fn warmup(&self) -> bool {
+        // SAFETY: upstream invariant: the sysvar data is created exclusively
+        // by the Solana runtime and serializes bool as 0x00 or 0x01.
+        self.warmup > 0
+    }
+
+    pub fn first_normal_epoch(&self) -> u64 {
+        u64::from_le_bytes(self.first_normal_epoch)
+    }
+
+    pub fn first_normal_slot(&self) -> u64 {
+        u64::from_le_bytes(self.first_normal_slot)
+    }
+}
+
+impl From<PodEpochSchedule> for EpochSchedule {
+    fn from(pod: PodEpochSchedule) -> Self {
+        Self {
+            slots_per_epoch: pod.slots_per_epoch(),
+            leader_schedule_slot_offset: pod.leader_schedule_slot_offset(),
+            warmup: pod.warmup(),
+            first_normal_epoch: pod.first_normal_epoch(),
+            first_normal_slot: pod.first_normal_slot(),
+        }
+    }
+}
+
 impl Sysvar for EpochSchedule {
-    impl_sysvar_get!(sol_get_epoch_schedule_sysvar);
+    fn get() -> Result<Self, solana_program_error::ProgramError> {
+        Ok(PodEpochSchedule::fetch()?.into())
+    }
 }
 
 #[cfg(feature = "bincode")]
 impl SysvarSerialize for EpochSchedule {}
+
+#[cfg(test)]
+mod tests {
+    use {super::*, crate::Sysvar, serial_test::serial};
+
+    #[test]
+    fn test_pod_epoch_schedule_conversion() {
+        let pod = PodEpochSchedule {
+            slots_per_epoch: 432000u64.to_le_bytes(),
+            leader_schedule_slot_offset: 432000u64.to_le_bytes(),
+            warmup: 1,
+            first_normal_epoch: 14u64.to_le_bytes(),
+            first_normal_slot: 524256u64.to_le_bytes(),
+        };
+
+        let epoch_schedule = EpochSchedule::from(pod);
+
+        assert_eq!(epoch_schedule.slots_per_epoch, 432000);
+        assert_eq!(epoch_schedule.leader_schedule_slot_offset, 432000);
+        assert!(epoch_schedule.warmup);
+        assert_eq!(epoch_schedule.first_normal_epoch, 14);
+        assert_eq!(epoch_schedule.first_normal_slot, 524256);
+    }
+
+    #[test]
+    #[serial]
+    #[cfg(feature = "bincode")]
+    fn test_epoch_schedule_get() {
+        let expected = EpochSchedule::custom(1234, 5678, false);
+        let data = bincode::serialize(&expected).unwrap();
+        assert_eq!(data.len(), 33);
+
+        crate::tests::mock_get_sysvar_syscall(&data);
+        let got = EpochSchedule::get().unwrap();
+        assert_eq!(got, expected);
+    }
+}
diff --git a/sysvar/src/fees.rs b/sysvar/src/fees.rs
index cf40e48ed..1a634e598 100644
--- a/sysvar/src/fees.rs
+++ b/sysvar/src/fees.rs
@@ -64,7 +64,7 @@ impl SysvarSerialize for Fees {}
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use {super::*, serial_test::serial};
 
     #[test]
     fn test_clone() {
@@ -76,4 +76,50 @@ mod tests {
         let cloned_fees = fees.clone();
         assert_eq!(cloned_fees, fees);
     }
+
+    struct MockFeesSyscall;
+    impl crate::program_stubs::SyscallStubs for MockFeesSyscall {
+        fn sol_get_fees_sysvar(&self, var_addr: *mut u8) -> u64 {
+            let fees = Fees {
+                fee_calculator: FeeCalculator {
+                    lamports_per_signature: 42,
+                },
+            };
+            unsafe {
+                std::ptr::copy_nonoverlapping(
+                    &fees as *const _ as *const u8,
+                    var_addr,
+                    core::mem::size_of::<Fees>(),
+                );
+            }
+            solana_program_entrypoint::SUCCESS
+        }
+    }
+
+    #[test]
+    #[serial]
+    fn test_fees_get_deprecated_syscall_path() {
+        let _ = crate::program_stubs::set_syscall_stubs(Box::new(MockFeesSyscall));
+        let got = Fees::get().unwrap();
+        assert_eq!(got.fee_calculator.lamports_per_signature, 42);
+    }
+
+    struct FailFeesSyscall;
+    impl crate::program_stubs::SyscallStubs for FailFeesSyscall {
+        fn sol_get_fees_sysvar(&self, _var_addr: *mut u8) -> u64 {
+            9999
+        }
+    }
+
+    #[test]
+    #[serial]
+    fn test_fees_get_deprecated_non_success_maps_to_unsupported() {
+        let prev = crate::program_stubs::set_syscall_stubs(Box::new(FailFeesSyscall));
+        let got = Fees::get();
+        assert_eq!(
+            got,
+            Err(solana_program_error::ProgramError::UnsupportedSysvar)
+        );
+        let _ = crate::program_stubs::set_syscall_stubs(prev);
+    }
 }
diff --git a/sysvar/src/last_restart_slot.rs b/sysvar/src/last_restart_slot.rs
index 5ee10b621..5689ddfb5 100644
--- a/sysvar/src/last_restart_slot.rs
+++ b/sysvar/src/last_restart_slot.rs
@@ -45,8 +45,40 @@ pub use {
 };
 
 impl Sysvar for LastRestartSlot {
-    impl_sysvar_get!(sol_get_last_restart_slot);
+    impl_sysvar_get!(id());
 }
 
 #[cfg(feature = "bincode")]
 impl SysvarSerialize for LastRestartSlot {}
+
+#[cfg(test)]
+mod tests {
+    use {super::*, crate::tests::to_bytes, serial_test::serial};
+
+    #[test]
+    #[cfg(feature = "bincode")]
+    fn test_last_restart_slot_size_matches_bincode() {
+        // Prove that LastRestartSlot's in-memory layout matches its bincode serialization.
+        let slot = LastRestartSlot::default();
+        let in_memory_size = core::mem::size_of::<LastRestartSlot>();
+        let bincode_size = bincode::serialized_size(&slot).unwrap() as usize;
+
+        assert_eq!(
+            in_memory_size, bincode_size,
+            "LastRestartSlot in-memory size ({in_memory_size}) must match bincode size ({bincode_size})",
+        );
+    }
+
+    #[test]
+    #[serial]
+    fn test_last_restart_slot_get_uses_sysvar_syscall() {
+        let expected = LastRestartSlot {
+            last_restart_slot: 9999,
+        };
+        let data = to_bytes(&expected);
+        crate::tests::mock_get_sysvar_syscall(&data);
+
+        let got = LastRestartSlot::get().unwrap();
+        assert_eq!(got, expected);
+    }
+}
diff --git a/sysvar/src/lib.rs b/sysvar/src/lib.rs
index 0e522f658..e9288281d 100644
--- a/sysvar/src/lib.rs
+++ b/sysvar/src/lib.rs
@@ -161,6 +161,9 @@ pub trait SysvarSerialize:
 /// Implements the [`Sysvar::get`] method for both SBF and host targets.
 #[macro_export]
 macro_rules! impl_sysvar_get {
+    // DEPRECATED: This variant is only for the deprecated Fees sysvar and should be
+    // removed once Fees is no longer in use. It uses the old-style direct syscall
+    // approach instead of the new sol_get_sysvar syscall.
     ($syscall_name:ident) => {
         fn get() -> Result<Self, $crate::__private::ProgramError> {
             let mut var = Self::default();
@@ -174,11 +177,43 @@ macro_rules! impl_sysvar_get {
 
             match result {
                 $crate::__private::SUCCESS => Ok(var),
-                // Unexpected errors are folded into `UnsupportedSysvar`.
                 _ => Err($crate::__private::ProgramError::UnsupportedSysvar),
             }
         }
     };
+    // Variant for sysvars with padding at the end. Loads bincode-serialized data
+    // (size - padding bytes) and zeros the padding to avoid undefined behavior.
+    // Only supports sysvars where padding is at the end of the layout. Caller
+    // must supply the correct number of padding bytes.
+    ($sysvar_id:expr, $padding:literal) => {
+        fn get() -> Result<Self, $crate::__private::ProgramError> {
+            let mut var = core::mem::MaybeUninit::<Self>::uninit();
+            let var_addr = var.as_mut_ptr() as *mut u8;
+            let length = core::mem::size_of::<Self>().saturating_sub($padding);
+            let sysvar_id_ptr = (&$sysvar_id) as *const _ as *const u8;
+            // SAFETY: The allocation is valid for `size_of::<Self>()`. We load
+            // `(size - padding)` bytes from the syscall, which matches bincode
+            // serialization. The remaining `padding` bytes are then zeroed.
+            let result =
+                unsafe { $crate::get_sysvar_unchecked(var_addr, sysvar_id_ptr, 0, length as u64) };
+            match result {
+                Ok(()) => {
+                    // SAFETY: All bytes now initialized: syscall filled data
+                    // bytes and we zeroed padding.
+                    unsafe {
+                        var_addr.add(length).write_bytes(0, $padding);
+                        Ok(var.assume_init())
+                    }
+                }
+                // Unexpected errors are folded into `UnsupportedSysvar`.
+                Err(_) => Err($crate::__private::ProgramError::UnsupportedSysvar),
+            }
+        }
+    };
+    // Variant for sysvars without padding (struct size matches bincode size).
+    ($sysvar_id:expr) => {
+        $crate::impl_sysvar_get!($sysvar_id, 0);
+    };
 }
 
 /// Handler for retrieving a slice of sysvar data from the `sol_get_sysvar`
@@ -206,6 +241,35 @@ pub fn get_sysvar(
     #[cfg(not(target_os = "solana"))]
     let result = crate::program_stubs::sol_get_sysvar(sysvar_id, var_addr, offset, length);
 
+    match result {
+        solana_program_entrypoint::SUCCESS => Ok(()),
+        OFFSET_LENGTH_EXCEEDS_SYSVAR => Err(solana_program_error::ProgramError::InvalidArgument),
+        _ => Err(solana_program_error::ProgramError::UnsupportedSysvar),
+    }
+}
+
+/// Internal helper for retrieving sysvar data directly into a raw buffer.
+///
+/// # Safety
+///
+/// This function bypasses the slice-length check that `get_sysvar` performs.
+/// The caller must ensure that `var_addr` points to a writable buffer of at
+/// least `length` bytes. This is typically used with `MaybeUninit` to load
+/// compact representations of sysvars.
+#[doc(hidden)]
+pub unsafe fn get_sysvar_unchecked(
+    var_addr: *mut u8,
+    sysvar_id: *const u8,
+    offset: u64,
+    length: u64,
+) -> Result<(), solana_program_error::ProgramError> {
+    #[cfg(target_os = "solana")]
+    let result =
+        solana_define_syscall::definitions::sol_get_sysvar(sysvar_id, var_addr, offset, length);
+
+    #[cfg(not(target_os = "solana"))]
+    let result = crate::program_stubs::sol_get_sysvar(sysvar_id, var_addr, offset, length);
+
     match result {
         solana_program_entrypoint::SUCCESS => Ok(()),
         OFFSET_LENGTH_EXCEEDS_SYSVAR => Err(solana_program_error::ProgramError::InvalidArgument),
@@ -245,10 +309,13 @@ mod tests {
     impl Sysvar for TestSysvar {}
     impl SysvarSerialize for TestSysvar {}
 
-    // NOTE tests that use this mock MUST carry the #[serial] attribute
+    // NOTE: Tests using these mocks MUST carry the #[serial] attribute
+    // because they modify global SYSCALL_STUBS state.
+
     struct MockGetSysvarSyscall {
         data: Vec<u8>,
     }
+
     impl SyscallStubs for MockGetSysvarSyscall {
         #[allow(clippy::arithmetic_side_effects)]
         fn sol_get_sysvar(
@@ -263,12 +330,65 @@ mod tests {
             SUCCESS
         }
     }
+
+    /// Mock syscall stub for tests. Requires `#[serial]` attribute.
     pub fn mock_get_sysvar_syscall(data: &[u8]) {
         set_syscall_stubs(Box::new(MockGetSysvarSyscall {
             data: data.to_vec(),
         }));
     }
 
+    struct ValidateIdSyscall {
+        data: Vec<u8>,
+        expected_id: Pubkey,
+    }
+
+    impl SyscallStubs for ValidateIdSyscall {
+        #[allow(clippy::arithmetic_side_effects)]
+        fn sol_get_sysvar(
+            &self,
+            sysvar_id_addr: *const u8,
+            var_addr: *mut u8,
+            offset: u64,
+            length: u64,
+        ) -> u64 {
+            // Validate that the correct sysvar id pointer was passed
+            let passed_id = unsafe { *(sysvar_id_addr as *const Pubkey) };
+            assert_eq!(passed_id, self.expected_id);
+
+            let slice = unsafe { std::slice::from_raw_parts_mut(var_addr, length as usize) };
+            slice.copy_from_slice(&self.data[offset as usize..(offset + length) as usize]);
+            SUCCESS
+        }
+    }
+
+    /// Mock syscall stub that validates sysvar ID. Requires `#[serial]` attribute.
+    pub fn mock_get_sysvar_syscall_with_id(
+        data: &[u8],
+        expected_id: &Pubkey,
+    ) -> Box<dyn SyscallStubs> {
+        set_syscall_stubs(Box::new(ValidateIdSyscall {
+            data: data.to_vec(),
+            expected_id: *expected_id,
+        }))
+    }
+
+    /// Convert a value to its in-memory byte representation.
+    ///
+    /// # Safety
+    ///
+    /// This function is only safe for plain-old-data types with no padding.
+    /// Intended for test use only.
+    pub fn to_bytes<T>(value: &T) -> Vec<u8> {
+        let size = core::mem::size_of::<T>();
+        let ptr = (value as *const T) as *const u8;
+        let mut data = vec![0u8; size];
+        unsafe {
+            std::ptr::copy_nonoverlapping(ptr, data.as_mut_ptr(), size);
+        }
+        data
+    }
+
     #[test]
     fn test_sysvar_account_info_to_from() {
         let test_sysvar = TestSysvar::default();
diff --git a/sysvar/src/program_stubs.rs b/sysvar/src/program_stubs.rs
index ba4180656..219cce02c 100644
--- a/sysvar/src/program_stubs.rs
+++ b/sysvar/src/program_stubs.rs
@@ -155,32 +155,6 @@ pub(crate) fn sol_get_sysvar(
         .sol_get_sysvar(sysvar_id_addr, var_addr, offset, length)
 }
 
-pub(crate) fn sol_get_clock_sysvar(var_addr: *mut u8) -> u64 {
-    SYSCALL_STUBS.read().unwrap().sol_get_clock_sysvar(var_addr)
-}
-
-pub(crate) fn sol_get_epoch_schedule_sysvar(var_addr: *mut u8) -> u64 {
-    SYSCALL_STUBS
-        .read()
-        .unwrap()
-        .sol_get_epoch_schedule_sysvar(var_addr)
-}
-
-pub(crate) fn sol_get_fees_sysvar(var_addr: *mut u8) -> u64 {
-    SYSCALL_STUBS.read().unwrap().sol_get_fees_sysvar(var_addr)
-}
-
-pub(crate) fn sol_get_rent_sysvar(var_addr: *mut u8) -> u64 {
-    SYSCALL_STUBS.read().unwrap().sol_get_rent_sysvar(var_addr)
-}
-
-pub(crate) fn sol_get_last_restart_slot(var_addr: *mut u8) -> u64 {
-    SYSCALL_STUBS
-        .read()
-        .unwrap()
-        .sol_get_last_restart_slot(var_addr)
-}
-
 pub fn sol_get_epoch_stake(vote_address: *const u8) -> u64 {
     SYSCALL_STUBS
         .read()
@@ -211,9 +185,6 @@ pub fn sol_get_stack_height() -> u64 {
     SYSCALL_STUBS.read().unwrap().sol_get_stack_height()
 }
 
-pub(crate) fn sol_get_epoch_rewards_sysvar(var_addr: *mut u8) -> u64 {
-    SYSCALL_STUBS
-        .read()
-        .unwrap()
-        .sol_get_epoch_rewards_sysvar(var_addr)
+pub(crate) fn sol_get_fees_sysvar(var_addr: *mut u8) -> u64 {
+    SYSCALL_STUBS.read().unwrap().sol_get_fees_sysvar(var_addr)
 }
diff --git a/sysvar/src/rent.rs b/sysvar/src/rent.rs
index 84f894cf6..a994dfaf0 100644
--- a/sysvar/src/rent.rs
+++ b/sysvar/src/rent.rs
@@ -128,9 +128,33 @@ pub use {
     solana_rent::Rent,
     solana_sdk_ids::sysvar::rent::{check_id, id, ID},
 };
+
 impl Sysvar for Rent {
-    impl_sysvar_get!(sol_get_rent_sysvar);
+    impl_sysvar_get!(id(), 7);
 }
 
 #[cfg(feature = "bincode")]
 impl SysvarSerialize for Rent {}
+
+#[cfg(test)]
+mod tests {
+    use {super::*, crate::Sysvar, serial_test::serial};
+
+    #[test]
+    #[serial]
+    #[cfg(feature = "bincode")]
+    #[allow(deprecated)]
+    fn test_rent_get() {
+        let expected = Rent {
+            lamports_per_byte_year: 123,
+            exemption_threshold: 2.5,
+            burn_percent: 7,
+        };
+        let data = bincode::serialize(&expected).unwrap();
+        assert_eq!(data.len(), 17);
+
+        crate::tests::mock_get_sysvar_syscall(&data);
+        let got = Rent::get().unwrap();
+        assert_eq!(got, expected);
+    }
+}