diff --git a/kernel/src/arch/x86_64/memory.rs b/kernel/src/arch/x86_64/memory.rs
index b2570a9..325b0b8 100644
--- a/kernel/src/arch/x86_64/memory.rs
+++ b/kernel/src/arch/x86_64/memory.rs
@@ -2,13 +2,13 @@ use crate::consts::KERNEL_OFFSET;
 use bit_allocator::BitAlloc;
 // Depends on kernel
 use super::{BootInfo, MemoryRegionType};
-use crate::memory::{active_table, init_heap, FRAME_ALLOCATOR, alloc_frame};
+use crate::memory::{active_table, alloc_frame, init_heap, FRAME_ALLOCATOR};
 use crate::HEAP_ALLOCATOR;
-use rcore_memory::PAGE_SIZE;
 use alloc::vec::Vec;
 use log::*;
 use once::*;
 use rcore_memory::paging::*;
+use rcore_memory::PAGE_SIZE;
 
 pub fn init(boot_info: &BootInfo) {
     assert_has_not_been_called!("memory::init must be called only once");
@@ -60,14 +60,12 @@ fn enlarge_heap() {
         addrs.push((va, PAGE_SIZE));
     }
     for (addr, len) in addrs.into_iter() {
-        for va in (addr..(addr+len)).step_by(PAGE_SIZE) {
+        for va in (addr..(addr + len)).step_by(PAGE_SIZE) {
             page_table.map(va, va - va_offset).update();
         }
         info!("Adding {:#X} {:#X} to heap", addr, len);
         unsafe {
-            HEAP_ALLOCATOR
-                .lock()
-                .init(addr, len);
+            HEAP_ALLOCATOR.lock().init(addr, len);
         }
     }
 }
diff --git a/kernel/src/drivers/block/ahci.rs b/kernel/src/drivers/block/ahci.rs
new file mode 100644
index 0000000..a84e577
--- /dev/null
+++ b/kernel/src/drivers/block/ahci.rs
@@ -0,0 +1,367 @@
+//! Driver for AHCI
+//!
+//! Spec: https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/serial-ata-ahci-spec-rev1-3-1.pdf
+
+use alloc::alloc::{alloc_zeroed, GlobalAlloc, Layout};
+use alloc::string::String;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
+use core::cmp::min;
+use core::mem::{size_of, zeroed};
+use core::slice;
+use core::str;
+
+use crate::sync::FlagsGuard;
+use bitflags::*;
+use device_tree::util::SliceRead;
+use device_tree::Node;
+use log::*;
+use rcore_memory::paging::PageTable;
+use rcore_memory::PAGE_SIZE;
+use volatile::Volatile;
+
+use rcore_fs::dev::BlockDevice;
+
+use crate::memory::active_table;
+use crate::sync::SpinNoIrqLock as Mutex;
+
+use super::super::bus::virtio_mmio::*;
+use super::super::{DeviceType, Driver, BLK_DRIVERS, DRIVERS};
+
+pub struct AHCI {
+    header: usize,
+    size: usize,
+    rfis: usize,
+    cmd_list: usize,
+    cmd_table: usize,
+    data: usize,
+}
+
+pub struct AHCIDriver(Mutex<AHCI>);
+
+// 3.1 Generic Host Control
+#[repr(C)]
+pub struct AHCIGHC {
+    cap: Volatile<AHCICap>,
+    ghc: Volatile<u32>,
+    is: Volatile<u32>,
+    pi: Volatile<u32>,
+    vs: Volatile<u32>,
+    ccc_ctl: Volatile<u32>,
+    ccc_ports: Volatile<u32>,
+    em_loc: Volatile<u32>,
+    em_ctl: Volatile<u32>,
+    cap2: Volatile<u32>,
+    bohc: Volatile<u32>,
+}
+
+bitflags! {
+    struct AHCICap : u32 {
+        const S64A = 1 << 31;
+        const SNCQ = 1 << 30;
+        const SSNTF = 1 << 29;
+        const SMPS = 1 << 28;
+        const SSS = 1 << 27;
+        const SALP = 1 << 26;
+        const SAL = 1 << 25;
+        const SCLO = 1 << 24;
+        const ISS_GEN_1 = 1 << 20;
+        const ISS_GEN_2 = 2 << 20;
+        const ISS_GEN_3 = 3 << 20;
+        const SAM = 1 << 18;
+        const SPM = 1 << 17;
+        const FBSS = 1 << 16;
+        const PMD = 1 << 15;
+        const SSC = 1 << 14;
+        const PSC = 1 << 13;
+        const CCCS = 1 << 7;
+        const EMS = 1 << 6;
+        const SXS = 1 << 5;
+        // number of ports = 1
+        const NP_1 = 1 << 0;
+        const NP_2 = 1 << 1;
+        const NP_4 = 1 << 2;
+        const NP_8 = 1 << 3;
+        const NP_16 = 1 << 4;
+    }
+}
+
+// 3.3 Port Registers (one set per port)
+#[repr(C)]
+pub struct AHCIPort {
+    clb: Volatile<u32>,
+    clbu: Volatile<u32>,
+    fb: Volatile<u32>,
+    fbu: Volatile<u32>,
+    is: Volatile<u32>,
+    ie: Volatile<u32>,
+    cmd: Volatile<u32>,
+    reserved: Volatile<u32>,
+    tfd: Volatile<u32>,
+    sig: Volatile<u32>,
+    ssts: Volatile<u32>,
+    sctl: Volatile<u32>,
+    serr: Volatile<u32>,
+    sact: Volatile<u32>,
+    ci: Volatile<u32>,
+    sntf: Volatile<u32>,
+    fbs: Volatile<u32>,
+    devslp: Volatile<u32>,
+}
+
+// 4.2.1 Received FIS Structure
+#[repr(C)]
+pub struct AHCIRFIS {
+    dma: [u8; 0x20],
+    pio: [u8; 0x20],
+    d2h: [u8; 0x18],
+    sdbfis: [u8; 0x8],
+    ufis: [u8; 0x40],
+    reserved: [u8; 0x60],
+}
+
+// 4.2.2 Command List Structure
+#[repr(C)]
+pub struct AHCICommandHeader {
+    pwa_cfl: u8,
+    pmp_cbr: u8,
+    prdtl: u16,
+    prdbc: u32,
+    ctba0: u32,
+    ctba_u0: u32,
+    reservec: [u32; 4],
+}
+
+// 4.2.3 Command Table
+#[repr(C)]
+pub struct AHCICommandTable {
+    cfis: [u8; 64],
+    acmd: [u8; 16],
+    reserved: [u8; 48],
+    prdt: [AHCIPRD; 1],
+}
+
+// 4.2.3 Command Table
+#[repr(C)]
+pub struct AHCIPRD {
+    dba: u32,
+    dbau: u32,
+    reserved: u32,
+    dbc_i: u32,
+}
+
+// https://wiki.osdev.org/AHCI
+#[repr(C)]
+#[derive(Default)]
+pub struct AHCIFISRegH2D {
+    fis_type: u8,
+    cflags: u8,
+    command: u8,
+    feature_lo: u8,
+    lba_0: u8,
+    lba_1: u8,
+    lba_2: u8,
+    device: u8,
+    lba_3: u8,
+    lba_4: u8,
+    lba_5: u8,
+    feature_hi: u8,
+    count_lo: u8,
+    count_hi: u8,
+    icc: u8,
+    control: u8,
+    sector_count_lo: u8,
+    sector_count_hi: u8,
+}
+
+// Table 29 IDENTIFY DEVICE data
+#[repr(C)]
+pub struct AHCIIdentifyPacket {
+    _1: [u16; 10],
+    serial: [u8; 20], // words 10-19
+    _2: [u16; 3],
+    firmware: [u8; 8], // words 23-26
+    model: [u8; 40],   // words 27-46
+    _3: [u16; 16],
+    lba_sectors: u32, // words 60-61
+}
+
+impl Driver for AHCIDriver {
+    fn try_handle_interrupt(&self, _irq: Option<u32>) -> bool {
+        let driver = self.0.lock();
+
+        // ensure header page is mapped
+        active_table().map_if_not_exists(driver.header as usize, driver.header as usize);
+        unimplemented!();
+        return false;
+    }
+
+    fn device_type(&self) -> DeviceType {
+        DeviceType::Block
+    }
+
+    fn get_id(&self) -> String {
+        format!("ahci")
+    }
+}
+
+const BLOCK_SIZE: usize = 512;
+impl BlockDevice for AHCIDriver {
+    const BLOCK_SIZE_LOG2: u8 = 9; // 512
+    fn read_at(&self, block_id: usize, buf: &mut [u8]) -> bool {
+        let mut driver = self.0.lock();
+        // ensure header page is mapped
+        active_table().map_if_not_exists(driver.header as usize, driver.header as usize);
+        unimplemented!()
+    }
+
+    fn write_at(&self, block_id: usize, buf: &[u8]) -> bool {
+        let mut driver = self.0.lock();
+        // ensure header page is mapped
+        active_table().map_if_not_exists(driver.header as usize, driver.header as usize);
+        unimplemented!()
+    }
+}
+
+fn from_ata_string(data: &[u8]) -> String {
+    let mut swapped_data = Vec::new();
+    assert!(data.len() % 2 == 0);
+    for i in (0..data.len()).step_by(2) {
+        swapped_data.push(data[i + 1]);
+        swapped_data.push(data[i]);
+    }
+    return String::from_utf8(swapped_data).unwrap();
+}
+
+pub fn ahci_init(irq: Option<u32>, header: usize, size: usize) -> Arc<AHCIDriver> {
+    let _ = FlagsGuard::no_irq_region();
+    if let None = active_table().get_entry(header) {
+        let mut current_addr = header;
+        while current_addr < header + size {
+            active_table().map_if_not_exists(current_addr, current_addr);
+            current_addr = current_addr + PAGE_SIZE;
+        }
+    }
+    let ghc = unsafe { &mut *(header as *mut AHCIGHC) };
+    debug!("header {:?}", ghc.cap);
+
+    // AHCI Enable
+    ghc.ghc.write(ghc.ghc.read() | (1 << 13));
+
+    let num_ports = (ghc.cap.read().bits() & 0x1f) as usize + 1;
+
+    for port_num in 0..num_ports {
+        if (ghc.pi.read() | (1 << port_num)) != 0 {
+            let addr = header + 0x100 + 0x80 * port_num;
+            let port = unsafe { &mut *(addr as *mut AHCIPort) };
+
+            // SSTS IPM Active
+            if (port.ssts.read() >> 8) & 0xF != 1 {
+                continue;
+            }
+
+            // SSTS DET Present
+            if port.ssts.read() & 0xF != 3 {
+                continue;
+            }
+
+            debug!("probing port {}", port_num);
+            // Disable Port First
+            port.cmd.write(port.cmd.read() & !(1 << 4 | 1 << 0));
+
+            let rfis_va =
+                unsafe { alloc_zeroed(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) }
+                    as usize;
+            let rfis_pa = active_table().get_entry(rfis_va).unwrap().target();
+
+            let cmd_list_va =
+                unsafe { alloc_zeroed(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) }
+                    as usize;
+            let cmd_list_pa = active_table().get_entry(cmd_list_va).unwrap().target();
+
+            let cmd_table_va =
+                unsafe { alloc_zeroed(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) }
+                    as usize;
+            let cmd_table_pa = active_table().get_entry(cmd_table_va).unwrap().target();
+
+            let data_va =
+                unsafe { alloc_zeroed(Layout::from_size_align(PAGE_SIZE, PAGE_SIZE).unwrap()) }
+                    as usize;
+            let data_pa = active_table().get_entry(data_va).unwrap().target();
+
+            let cmd_headers = unsafe {
+                slice::from_raw_parts_mut(
+                    cmd_list_va as *mut AHCICommandHeader,
+                    PAGE_SIZE / size_of::<AHCICommandHeader>(),
+                )
+            };
+
+            let cmd_table = unsafe { &mut *(cmd_table_va as *mut AHCICommandTable) };
+
+            cmd_table.prdt[0].dba = data_pa as u32;
+            cmd_table.prdt[0].dbau = (data_pa >> 32) as u32;
+            cmd_table.prdt[0].dbc_i = (BLOCK_SIZE - 1) as u32;
+
+            cmd_headers[0].ctba0 = cmd_table_pa as u32;
+            cmd_headers[0].ctba_u0 = (cmd_table_pa >> 32) as u32;
+            cmd_headers[0].prdtl = 1;
+            cmd_headers[0].prdbc = 0;
+
+            port.clb.write(cmd_list_pa as u32);
+            port.clbu.write((cmd_list_pa >> 32) as u32);
+
+            port.fb.write(rfis_pa as u32);
+            port.fbu.write((rfis_pa >> 32) as u32);
+
+            // clear status and errors
+            port.ci.write(0);
+            port.sact.write(0);
+            port.serr.write(0);
+
+            // enable port
+            port.cmd
+                .write(port.cmd.read() | 1 << 0 | 1 << 1 | 1 << 2 | 1 << 4 | 1 << 28);
+
+            let stat = port.ssts.read();
+            if stat == 0 {
+                warn!("port is not connected to external drive?");
+            }
+
+            let fis = unsafe { &mut *(cmd_table.cfis.as_ptr() as *mut AHCIFISRegH2D) };
+            // Register FIS from host to device
+            fis.fis_type = 0x27;
+            fis.cflags = 1 << 7;
+
+            // 7.15 IDENTIFY DEVICE - ECh, PIO Data-In
+            fis.command = 0xec; // ide identify
+            fis.sector_count_lo = 1;
+
+            debug!("issued identify command");
+            port.ci.write(1 << 0);
+
+            loop {
+                let stat = port.tfd.read();
+                let ci = port.ci.read();
+                if stat & 0x80 == 0 || (ci & (1 << 0)) == 0 {
+                    break;
+                }
+            }
+
+            let identify_data = unsafe { &*(data_va as *mut AHCIIdentifyPacket) };
+
+            unsafe {
+                debug!(
+                    "{:?} {:?} {:?} {}",
+                    from_ata_string(&identify_data.serial),
+                    from_ata_string(&identify_data.firmware),
+                    from_ata_string(&identify_data.model),
+                    identify_data.lba_sectors
+                );
+            }
+
+            break;
+        }
+    }
+
+    unimplemented!();
+}
diff --git a/kernel/src/syscall/misc.rs b/kernel/src/syscall/misc.rs
index fc6779f..ac3ff39 100644
--- a/kernel/src/syscall/misc.rs
+++ b/kernel/src/syscall/misc.rs
@@ -1,8 +1,8 @@
 use super::*;
 use crate::arch::cpu;
+use crate::consts::USER_STACK_SIZE;
 use core::mem::size_of;
 use core::sync::atomic::{AtomicI32, Ordering};
-use crate::consts::USER_STACK_SIZE;
 
 pub fn sys_arch_prctl(code: i32, addr: usize, tf: &mut TrapFrame) -> SysResult {
     const ARCH_SET_FS: i32 = 0x1002;
@@ -177,7 +177,7 @@ pub fn sys_prlimit64(
                 }
             }
             Ok(0)
-        },
+        }
         RLIMIT_RSS | RLIMIT_AS => {
             if !old_limit.is_null() {
                 proc.vm.check_write_ptr(old_limit)?;
diff --git a/user b/user
index 8af7200..ec476c3 160000
--- a/user
+++ b/user
@@ -1 +1 @@
-Subproject commit 8af72001d15af969c2e7c4feec43d8f9efe9331e
+Subproject commit ec476c3acb600c6d437454e74fb3e0eb6c452de4