diff --git a/include/sys/amd64/hw/ide/ahci.h b/include/sys/amd64/hw/ide/ahci.h
index 58a8a4e..d35d851 100644
--- a/include/sys/amd64/hw/ide/ahci.h
+++ b/include/sys/amd64/hw/ide/ahci.h
@@ -222,8 +222,8 @@ struct ahci_command_table_entry {
 
 uint32_t ahci_irq(void *ctx);
 
-// TODO: accept block device instead of port registers
 void ahci_sata_read(struct ahci_port_registers *port, void *buf, uint32_t nsect, uint64_t lba);
+void ahci_sata_write(struct ahci_port_registers *port, const void *buf, uint32_t nsect, uint64_t lba);
 
 void ahci_port_start(struct ahci_port_registers *port);
 void ahci_port_stop(struct ahci_port_registers *port);
diff --git a/include/sys/amd64/hw/ide/ata.h b/include/sys/amd64/hw/ide/ata.h
index 5c9ef88..9a24cfd 100644
--- a/include/sys/amd64/hw/ide/ata.h
+++ b/include/sys/amd64/hw/ide/ata.h
@@ -26,6 +26,7 @@
 #define ATA_CMD_READ_PIO_EX     0x24
 #define ATA_CMD_READ_DMA        0xC8
 #define ATA_CMD_READ_DMA_EX     0x25
+#define ATA_CMD_WRITE_DMA_EX    0x35
 
 #define ATA_SR_BUSY             (1 << 7)
 #define ATA_SR_DRQ              (1 << 3)
diff --git a/sys/amd64/grub.cfg b/sys/amd64/grub.cfg
deleted file mode 100644
index 2edf696..0000000
--- a/sys/amd64/grub.cfg
+++ /dev/null
@@ -1,5 +0,0 @@
-menuentry "yggdrasil" {
-    multiboot /boot/loader
-    module /boot/kernel kernel
-    module /boot/initrd.img initrd
-}
diff --git a/sys/amd64/hw/ide/ahci.c b/sys/amd64/hw/ide/ahci.c
index c220e82..aa8f560 100644
--- a/sys/amd64/hw/ide/ahci.c
+++ b/sys/amd64/hw/ide/ahci.c
@@ -48,6 +48,19 @@ static ssize_t ahci_blk_read(struct blkdev *blk, void *buf, size_t off, size_t c
     return count;
 }
 
+static ssize_t ahci_blk_write(struct blkdev *blk, const void *buf, size_t off, size_t count) {
+    _assert(blk && blk->dev_data);
+    _assert(!(off & 511));
+    _assert(!(count & 511));
+
+    size_t nsect = count / 512;
+    size_t lba = off / 512;
+
+    ahci_sata_write((struct ahci_port_registers *) blk->dev_data, buf, nsect, lba);
+
+    return count;
+}
+
 static int ahci_add_port_dev(struct ahci_port_registers *port) {
     void *buf = kmalloc(sizeof(struct blkdev) + sizeof(struct dev_entry));
     struct dev_entry *ent = (struct dev_entry *) buf;
@@ -56,6 +69,7 @@ static int ahci_add_port_dev(struct ahci_port_registers *port) {
 
     blk->dev_data = port;
     blk->read = ahci_blk_read;
+    blk->write = ahci_blk_write;
 
     ent->dev = blk;
     ent->dev_class = DEV_CLASS_BLOCK;
@@ -84,7 +98,8 @@ uint32_t ahci_irq(void *ctx) {
     return IRQ_UNHANDLED;
 }
 
-void ahci_sata_read(struct ahci_port_registers *port, void *buf, uint32_t nsect, uint64_t lba) {
+static void ahci_sata_access(struct ahci_port_registers *port, void *buf, uint32_t nsect, uint64_t lba, uint8_t dir) {
+    kdebug("%s access to AHCI drive\n", dir ? "Write" : "Read");
     port->p_is = -1;
 
     int cmd = ahci_alloc_cmd(port);
@@ -101,7 +116,7 @@ void ahci_sata_read(struct ahci_port_registers *port, void *buf, uint32_t nsect,
     size_t prd_count = (byte_count + 8191) / 8192;
 
     if (prd_count > 8) {
-        panic("Read operation uses too many PRDT entries\n");
+        panic("Too many PRDT entries\n");
     }
 
     size_t bytes_left = byte_count;
@@ -135,11 +150,11 @@ void ahci_sata_read(struct ahci_port_registers *port, void *buf, uint32_t nsect,
 
     _assert(!bytes_left);
 
-    // Prepare read command
+    // Prepare command
     struct ahci_fis_reg_h2d *fis_reg_h2d = &cmd_table->fis_reg_h2d;
     memset(fis_reg_h2d, 0, sizeof(struct ahci_fis_reg_h2d));
     fis_reg_h2d->type = FIS_REG_H2D;
-    fis_reg_h2d->cmd = ATA_CMD_READ_DMA_EX;
+    fis_reg_h2d->cmd = dir ? ATA_CMD_WRITE_DMA_EX : ATA_CMD_READ_DMA_EX;
     fis_reg_h2d->cmd_port = 1 << 7;
     fis_reg_h2d->lba0 = lba & 0xFF;
     fis_reg_h2d->lba1 = (lba >> 8) & 0xFF;
@@ -178,6 +193,14 @@ void ahci_sata_read(struct ahci_port_registers *port, void *buf, uint32_t nsect,
     }
 }
 
+void ahci_sata_read(struct ahci_port_registers *port, void *buf, uint32_t nsect, uint64_t lba) {
+    ahci_sata_access(port, buf, nsect, lba, 0);
+}
+
+void ahci_sata_write(struct ahci_port_registers *port, const void *buf, uint32_t nsect, uint64_t lba) {
+    ahci_sata_access(port, (void *) buf, nsect, lba, 1);
+}
+
 static void ahci_sata_port_identify(struct ahci_port_registers *port) {
     port->p_is = -1;
 
diff --git a/sys/blk.c b/sys/blk.c
index 8f1028c..77e1436 100644
--- a/sys/blk.c
+++ b/sys/blk.c
@@ -89,6 +89,20 @@ int blk_mount_auto(struct vfs_node *at, struct blkdev *blk, const char *opt) {
     return -1;
 }
 
+static ssize_t blk_part_write(struct blkdev *dev, const void *buf, size_t off, size_t count) {
+    struct blk_part *part = (struct blk_part *) dev->dev_data;
+    size_t part_size_bytes = part->lba_size * 512;
+    size_t part_off_bytes = part->lba_start * 512;
+
+    if (off >= part_size_bytes) {
+        return -1;
+    }
+
+    size_t l = MIN(part_size_bytes - off, count);
+
+    return blk_write(part->device, buf, off + part_off_bytes, l);
+}
+
 static ssize_t blk_part_read(struct blkdev *dev, void *buf, size_t off, size_t count) {
     struct blk_part *part = (struct blk_part *) dev->dev_data;
     size_t part_size_bytes = part->lba_size * 512;
@@ -129,6 +143,7 @@ static int blk_enumerate_mbr(struct blkdev *dev, uint8_t *head) {
 
             blk->dev_data = part;
             blk->read = blk_part_read;
+            blk->write = blk_part_write;
             blk->ent_parent = dev->ent;
 
             ent->dev = blk;
@@ -174,6 +189,7 @@ static int blk_enumerate_gpt(struct blkdev *dev, uint8_t *head) {
 
             blk->dev_data = part;
             blk->read = blk_part_read;
+            blk->write = blk_part_write;
             blk->ent_parent = dev->ent;
 
             ent->dev = blk;
diff --git a/sys/vfs/ext2/ext2alloc.c b/sys/vfs/ext2/ext2alloc.c
index 3780b13..87d267e 100644
--- a/sys/vfs/ext2/ext2alloc.c
+++ b/sys/vfs/ext2/ext2alloc.c
@@ -22,7 +22,7 @@ int ext2_alloc_block(fs_t *ext2, uint32_t *block_no) {
     for (size_t i = 0; i < sb->block_group_count; ++i) {
         if (sb->block_group_descriptor_table[i].free_blocks > 0) {
             // Found a free block here
-            kdebug("Allocating a block in group #%zu\n", i);
+            kdebug("Allocating a block in group #%u\n", i);
 
             if ((res = ext2_read_block(ext2,
                                        sb->block_group_descriptor_table[i].block_usage_bitmap_block,
@@ -244,7 +244,7 @@ int ext2_alloc_inode(fs_t *ext2, uint32_t *ino) {
     for (size_t i = 0; i < sb->block_group_count; ++i) {
         if (sb->block_group_descriptor_table[i].free_inodes > 0) {
             // Found a block group with free inodes
-            kdebug("Allocating an inode inside block group #%zu\n", i);
+            kdebug("Allocating an inode inside block group #%u\n", i);
 
             // Read inode usage bitmap
             if ((res = ext2_read_block(ext2,