diff --git a/src/runtime/src/comms.rs b/src/runtime/src/comms.rs
index e14e7c6..2fa3c8e 100644
--- a/src/runtime/src/comms.rs
+++ b/src/runtime/src/comms.rs
@@ -32,6 +32,7 @@ use crate::moninj;
 use crate::mgmt;
 use crate::analyzer;
 use crate::rtio_mgt::{self, resolve_channel_name};
+use crate::io_expander;
 #[cfg(has_drtio)]
 use crate::pl;
 
@@ -380,7 +381,7 @@ async fn handle_connection(stream: &mut TcpStream, control: Rc<RefCell<kernel::C
     }
 }
 
-pub fn main(timer: GlobalTimer, cfg: Config) {
+pub fn main(timer: GlobalTimer, cfg: Config, mut io_expander0: io_expander::IoExpander, mut io_expander1: io_expander::IoExpander) {
     let net_addresses = net_settings::get_addresses(&cfg);
     info!("network addresses: {}", net_addresses);
 
@@ -494,6 +495,11 @@ pub fn main(timer: GlobalTimer, cfg: Config) {
                 let _ = stream.flush().await;
                 let _ = stream.abort().await;
             });
+            #[cfg(feature = "target_kasli_soc")]
+            {
+                io_expander0.service().expect("I2C I/O expander #0 service failed");
+                io_expander1.service().expect("I2C I/O expander #1 service failed");
+            }
         }
     });
 
diff --git a/src/runtime/src/io_expander.rs b/src/runtime/src/io_expander.rs
index e83f763..8fcb75c 100644
--- a/src/runtime/src/io_expander.rs
+++ b/src/runtime/src/io_expander.rs
@@ -1,7 +1,8 @@
-use crate::pl::csr;
 use crate::i2c;
+use log::info;
 
 // Only the bare minimum registers. Bits/IO connections equivalent between IC types.
+#[cfg(feature = "target_kasli_soc")]
 struct Registers {
     // PCA9539 equivalent register names in comments
     iodira: u8, // Configuration Port 0
@@ -10,6 +11,7 @@ struct Registers {
     gpiob: u8,  // Output Port 1
 }
 
+#[cfg(feature = "target_kasli_soc")]
 pub struct IoExpander {
     busno: i32,
     port: u8,
@@ -21,8 +23,18 @@ pub struct IoExpander {
     registers: Registers,
 }
 
+#[cfg(not(feature = "target_kasli_soc"))]
+pub struct IoExpander;
+
+#[cfg(not(feature = "target_kasli_soc"))]
+impl IoExpander {
+    pub fn new(index: u8) -> Result<Self, &'static str> {
+        Ok(IoExpander {})
+    }
+}
+
+#[cfg(feature = "target_kasli_soc")]
 impl IoExpander {
-    #[cfg(feature = "target_kasli_soc")]
     pub fn new(index: u8) -> Result<Self, &'static str> {
         const VIRTUAL_LED_MAPPING0: [(u8, u8, u8); 2] = [(0, 0, 6), (1, 1, 6)];
         const VIRTUAL_LED_MAPPING1: [(u8, u8, u8); 2] = [(2, 0, 6), (3, 1, 6)];
@@ -62,8 +74,7 @@ impl IoExpander {
             _ => return Err("incorrect I/O expander index"),
         };
         if !io_expander.check_ack()? {
-            #[cfg(feature = "log")]
-            log::info!(
+            info!(
                 "MCP23017 io expander {} not found. Checking for PCA9539.",
                 index
             );
@@ -81,19 +92,13 @@ impl IoExpander {
         Ok(io_expander)
     }
 
-    #[cfg(feature = "target_kasli_soc")]
     fn select(&self) -> Result<(), &'static str> {
-        let mask: i32 = 1 << self.port;
-        i2c::switch_select(self.busno, 0x70, mask);
-        i2c::switch_select(self.busno, 0x71, (mask >> 8));
+        let mask: u16 = 1 << self.port;
+        i2c::switch_select(self.busno, 0x70, mask as u8 as i32);
+        i2c::switch_select(self.busno, 0x71, (mask >> 8) as u8 as i32);
         Ok(())
     }
 
-    #[cfg(not(feature = "target_kasli_soc"))]
-    fn select(&self) -> Result<(), &'static str> {
-        Err("the target is not supported yet")
-    }
-
     fn write(&self, addr: u8, value: u8) -> Result<(), &'static str> {
         i2c::start(self.busno);
         i2c::write(self.busno, self.address as i32);
@@ -148,8 +153,7 @@ impl IoExpander {
     }
 
     pub fn service(&mut self) -> Result<(), &'static str> {
-        for (led, port, bit) in self.virtual_led_mapping.iter() {
-            //let level = unsafe { (csr::virtual_leds::status_read() >> led) & 1 };
+        for (_led, port, bit) in self.virtual_led_mapping.iter() {
             self.set(*port, *bit, true);
         }
 
diff --git a/src/runtime/src/main.rs b/src/runtime/src/main.rs
index 5ee7e5d..09e272e 100644
--- a/src/runtime/src/main.rs
+++ b/src/runtime/src/main.rs
@@ -46,7 +46,6 @@ mod mgmt;
 mod analyzer;
 mod irq;
 mod i2c;
-#[cfg(feature = "target_kasli_soc")]
 mod io_expander;
 
 static mut SEEN_ASYNC_ERRORS: u8 = 0;
@@ -116,6 +115,25 @@ pub fn main_core0() {
 
     i2c::init();
 
+    let (mut io_expander0, mut io_expander1) = (io_expander::IoExpander::new(0).unwrap(), io_expander::IoExpander::new(1).unwrap());
+    #[cfg(feature = "target_kasli_soc")]
+    {
+        io_expander0.init().expect("I2C I/O expander #0 initialization failed");
+        io_expander1.init().expect("I2C I/O expander #1 initialization failed");
+
+        // Actively drive TX_DISABLE to false on SFP0..3
+        io_expander0.set_oe(0, 1 << 1).unwrap();
+        io_expander0.set_oe(1, 1 << 1).unwrap();
+        io_expander1.set_oe(0, 1 << 1).unwrap();
+        io_expander1.set_oe(1, 1 << 1).unwrap();
+        io_expander0.set(0, 1, false);
+        io_expander0.set(1, 1, false);
+        io_expander1.set(0, 1, false);
+        io_expander1.set(1, 1, false);
+        io_expander0.service().unwrap();
+        io_expander1.service().unwrap();
+    }
+
     let cfg = match Config::new() {
         Ok(cfg) => cfg,
         Err(err) => {
@@ -128,5 +146,5 @@ pub fn main_core0() {
 
     task::spawn(report_async_rtio_errors());
 
-    comms::main(timer, cfg);
+    comms::main(timer, cfg, io_expander0, io_expander1);
 }