diff --git a/boot/limine/entry.c b/boot/limine/entry.c
index 885466b..804979e 100644
--- a/boot/limine/entry.c
+++ b/boot/limine/entry.c
@@ -2,8 +2,8 @@
 #include <zinnia/cmdline.h>
 #include <zinnia/init.h>
 #include <zinnia/print.h>
-#include <zinnia/utils.h>
 #include <zinnia/string.h>
+#include <zinnia/utils.h>
 #include "limine.h"
 
 [[__initdata_sorted("limine.0")]]
diff --git a/core/dpc.c b/core/dpc.c
new file mode 100644
index 0000000..8fb7e6b
--- /dev/null
+++ b/core/dpc.c
@@ -0,0 +1,3 @@
+#include <zinnia/dpc.h>
+
+// TODO
diff --git a/core/lib/runtime.c b/core/lib/runtime.c
index 681a13b..4aa8e75 100644
--- a/core/lib/runtime.c
+++ b/core/lib/runtime.c
@@ -1,5 +1,4 @@
-// Compiler runtime support like libgcc or compiler-rt.
-// Extend as required.
+// Compiler runtime support.
 
 #include <stdint.h>
 
diff --git a/core/mem/pmap.c b/core/mem/pmap.c
index ec6d243..8f64beb 100644
--- a/core/mem/pmap.c
+++ b/core/mem/pmap.c
@@ -2,9 +2,9 @@
 #include <zinnia/errno.h>
 #include <zinnia/pmap.h>
 #include <zinnia/spin.h>
+#include <zinnia/string.h>
 #include <zinnia/vma.h>
 #include <config.h>
-#include <zinnia/string.h>
 
 // TODO: For now, we assume that we can do generic PTE lookups on every arch that has a MMU.
 static_assert(CONFIG_HAVE_MMU_GENERIC);
diff --git a/core/mem/pmm.c b/core/mem/pmm.c
index 530281b..a6a66ae 100644
--- a/core/mem/pmm.c
+++ b/core/mem/pmm.c
@@ -3,9 +3,9 @@
 #include <zinnia/panic.h>
 #include <zinnia/print.h>
 #include <zinnia/spin.h>
+#include <zinnia/string.h>
 #include <zinnia/virt.h>
 #include <stdint.h>
-#include <zinnia/string.h>
 
 uintptr_t mem_hhdm_base = 0;
 
diff --git a/core/mem/vma.c b/core/mem/vma.c
index 0bbb352..0f47df1 100644
--- a/core/mem/vma.c
+++ b/core/mem/vma.c
@@ -60,7 +60,7 @@ static struct vma_mapping* find_mapping(struct vma* v, size_t page) {
     return nullptr;
 }
 
-static bool access_allowed(enum prot_flags prot, const struct vma_fault_info* info) {
+static bool can_access(enum prot_flags prot, const struct vma_fault_info* info) {
     if (info->caused_by_write)
         return prot & PROT_WRITE;
     if (info->caused_by_fetch)
@@ -87,7 +87,7 @@ bool vma_page_fault(struct vma* v, const struct vma_fault_info* info) {
 
     spin_lock(&v->lock);
     struct vma_mapping* mapping = find_mapping(v, faulty_page);
-    if (!mapping || !access_allowed(mapping->prot, info)) {
+    if (!mapping || !can_access(mapping->prot, info)) {
         spin_unlock(&v->lock);
         return false;
     }
@@ -107,8 +107,7 @@ bool vma_page_fault(struct vma* v, const struct vma_fault_info* info) {
     spin_lock(&v->lock);
     mapping = find_mapping(v, faulty_page);
     const bool still_valid = mapping && mapping->object == object &&
-        (faulty_page - mapping->start_page) + mapping->offset_page == object_page &&
-        access_allowed(mapping->prot, info);
+        (faulty_page - mapping->start_page) + mapping->offset_page == object_page && can_access(mapping->prot, info);
 
     if (still_valid) {
         errno_t status =
diff --git a/core/mem/vmo.c b/core/mem/vmo.c
index 9239056..5cc4be0 100644
--- a/core/mem/vmo.c
+++ b/core/mem/vmo.c
@@ -1,9 +1,9 @@
 #include <zinnia/alloc.h>
 #include <zinnia/errno.h>
 #include <zinnia/list.h>
+#include <zinnia/string.h>
 #include <zinnia/utils.h>
 #include <zinnia/vmo.h>
-#include <zinnia/string.h>
 
 void vmo_ref(struct vmo* obj) {
     refcount_inc(&obj->rc);
@@ -211,6 +211,25 @@ errno_t vmo_new_phys(struct paged_vmo** out) {
     return vmo_new_paged(phys_pager, out);
 }
 
+void vmo_truncate_paged(struct paged_vmo* paged, size_t length) {
+    const size_t page_size = arch_mem_page_size();
+    const size_t keep_pages = ROUND_UP(length, page_size) / page_size;
+
+    spin_lock(&paged->lock);
+    struct page_list** pp = &list_first(&paged->cache);
+    while (*pp) {
+        struct page_list* entry = *pp;
+        if (entry->offset >= keep_pages) {
+            *pp = list_next(entry, next);
+            paged->source.put_page(&paged->source, entry->offset, entry->value);
+            mem_free(entry);
+        } else {
+            pp = &list_next(entry, next);
+        }
+    }
+    spin_unlock(&paged->lock);
+}
+
 struct phys_range_vmo {
     struct vmo object;
     uintptr_t start;
diff --git a/core/meson.build b/core/meson.build
index 18c343c..cfba785 100644
--- a/core/meson.build
+++ b/core/meson.build
@@ -1,7 +1,6 @@
 kernel_sources += files(
     'clock.c',
     'console.c',
-    'elf.c',
     'irq.c',
     'module.c',
     'panic.c',
diff --git a/core/percpu.c b/core/percpu.c
index 6e01802..5ce3522 100644
--- a/core/percpu.c
+++ b/core/percpu.c
@@ -29,6 +29,9 @@ struct percpu* percpu_new() {
     const size_t size = __ld_percpu_end - __ld_percpu_start;
     const size_t num_pages = ALIGN_UP(size, arch_mem_page_size()) / arch_mem_page_size();
 
+    // TODO: Map pages past the end of the kernel.
+    // TODO: Document how allocations work.
+
     phys_t mem;
     if (mem_phys_alloc(num_pages, 0, &mem))
         return nullptr;
diff --git a/core/spin.c b/core/spin.c
index 13d9d90..1da5ea8 100644
--- a/core/spin.c
+++ b/core/spin.c
@@ -1,6 +1,11 @@
 #include <zinnia/spin.h>
 #include <stdatomic.h>
 
+void spin_init(struct spinlock* spin) {
+    spin->next = 0;
+    spin->owner = 0;
+}
+
 void spin_lock(struct spinlock* spin) {
     uint32_t my = atomic_fetch_add_explicit(&spin->next, 1, memory_order_relaxed);
 
diff --git a/dev/meson.build b/dev/meson.build
index 47f1f05..3837470 100644
--- a/dev/meson.build
+++ b/dev/meson.build
@@ -1,12 +1,9 @@
 subdir('common')
 subdir('block')
+subdir('dt')
 
 if kconfig.get('CONFIG_ACPI', 'n') == 'y'
     subdir('acpi')
 endif
 
-if kconfig.get('CONFIG_DT', 'n') == 'y'
-    subdir('dt')
-endif
-
 module_lds = meson.current_source_dir() / 'module.ld'
diff --git a/core/elf.c b/fs/exec/elf.c
similarity index 99%
rename from core/elf.c
rename to fs/exec/elf.c
index c1c0b6b..d073c89 100644
--- a/core/elf.c
+++ b/fs/exec/elf.c
@@ -9,6 +9,7 @@
 #include <zinnia/sched.h>
 #include <zinnia/string.h>
 #include <zinnia/utils.h>
+#include <zinnia/vfs.h>
 #include <zinnia/vma.h>
 #include <zinnia/vmo.h>
 #include <bits/elf.h>
diff --git a/fs/exec/meson.build b/fs/exec/meson.build
new file mode 100644
index 0000000..a389904
--- /dev/null
+++ b/fs/exec/meson.build
@@ -0,0 +1,3 @@
+kernel_sources += files(
+    'elf.c',
+)
diff --git a/fs/meson.build b/fs/meson.build
index 7578f28..a715240 100644
--- a/fs/meson.build
+++ b/fs/meson.build
@@ -1 +1 @@
-subdir('tmpfs')
+subdir('exec')
\ No newline at end of file
diff --git a/fs/tmpfs/meson.build b/fs/tmpfs/meson.build
deleted file mode 100644
index 4e4da64..0000000
--- a/fs/tmpfs/meson.build
+++ /dev/null
@@ -1 +0,0 @@
-kernel_sources += files('tmpfs.c')
diff --git a/fs/tmpfs/tmpfs.c b/fs/tmpfs/tmpfs.c
deleted file mode 100644
index 70b786d..0000000
--- a/fs/tmpfs/tmpfs.c
+++ /dev/null
@@ -1 +0,0 @@
-// TODO
diff --git a/fs/vfs/ident.c b/fs/vfs/ident.c
new file mode 100644
index 0000000..24cf39d
--- /dev/null
+++ b/fs/vfs/ident.c
@@ -0,0 +1,7 @@
+#include <zinnia/ident.h>
+
+static const struct ident kernel_identity = {0};
+
+const struct ident* ident_kernel() {
+    return &kernel_identity;
+}
diff --git a/fs/vfs/meson.build b/fs/vfs/meson.build
new file mode 100644
index 0000000..9d4787d
--- /dev/null
+++ b/fs/vfs/meson.build
@@ -0,0 +1,3 @@
+kernel_sources += files(
+    'ident.c',
+)
diff --git a/include/uapi/time.h b/include/uapi/time.h
index 8bacd36..04b4167 100644
--- a/include/uapi/time.h
+++ b/include/uapi/time.h
@@ -17,12 +17,12 @@ struct __timeval {
     __suseconds_t tv_usec;
 };
 
-struct itimerval {
+struct __itimerval {
     struct __timeval it_interval;
     struct __timeval it_value;
 };
 
-struct itimerspec {
+struct __itimerspec {
     struct __timespec it_interval;
     struct __timespec it_value;
 };
diff --git a/include/zinnia/alloc.h b/include/zinnia/alloc.h
index fa3206c..ca62518 100644
--- a/include/zinnia/alloc.h
+++ b/include/zinnia/alloc.h
@@ -26,7 +26,10 @@ struct phys_mem {
 
 // Base address of the HHDM.
 extern uintptr_t mem_hhdm_base;
-#define HHDM_PTR(paddr) (void*)(mem_hhdm_base + (paddr))
+
+static inline void* HHDM_PTR(phys_t paddr) {
+    return (void*)(mem_hhdm_base + paddr);
+}
 
 // Allocates a region of memory which can be smaller than the page size.
 // Returns `nullptr` if the allocator cannot provide an allocation for the given `length` + `flags`.
diff --git a/include/zinnia/dpc.h b/include/zinnia/dpc.h
new file mode 100644
index 0000000..d0620fc
--- /dev/null
+++ b/include/zinnia/dpc.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <zinnia/list.h>
+#include <zinnia/percpu.h>
+#include <stdatomic.h>
+
+struct dpc {
+    void (*const callback)(struct dpc* dpc, void* data);
+    void* data;
+    atomic_bool inserted;
+
+    list_link(struct dpc*) link;
+};
+
+void dpc_dispatch();
+
+struct dpc_percpu {};
+extern struct dpc_percpu dpc_percpu_data;
diff --git a/include/zinnia/elf.h b/include/zinnia/elf.h
index 03a5c23..9923a0f 100644
--- a/include/zinnia/elf.h
+++ b/include/zinnia/elf.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <zinnia/errno.h>
+#include <zinnia/vfs.h>
 #include <bits/elf.h>
 #include <stdint.h>
 
@@ -341,15 +342,4 @@ static inline uint32_t ELF64_R_TYPE(uint64_t info) {
     return info & 0xFFFFFFFF;
 }
 
-struct vma;
-struct vmo;
-struct task;
-
-struct exec_info {
-    struct vma* space;
-    struct vmo* file_obj;
-    const char** argv;
-    const char** envp;
-};
-
 errno_t elf_load(struct exec_info* info, struct task** out);
diff --git a/include/zinnia/fdt.h b/include/zinnia/fdt.h
new file mode 100644
index 0000000..25e16f9
--- /dev/null
+++ b/include/zinnia/fdt.h
@@ -0,0 +1,45 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct fdt_header {
+    uint32_t magic;
+    uint32_t total_size;
+    uint32_t structs_offset;
+    uint32_t strings_offset;
+    uint32_t reserved_offset;
+    uint32_t version;
+    uint32_t compat_version;
+    uint32_t boot_cpuid;
+    uint32_t strings_size;
+    uint32_t structs_size;
+};
+
+constexpr uint32_t FDT_BEGIN_NODE = 0x00000001;
+constexpr uint32_t FDT_END_NODE = 0x00000002;
+constexpr uint32_t FDT_PROP = 0x00000003;
+constexpr uint32_t FDT_NOP = 0x00000004;
+constexpr uint32_t FDT_END = 0x00000009;
+
+struct fdt {
+    uint32_t version;
+    uint32_t compat_version;
+    uint32_t boot_cpuid;
+
+    const uint8_t* structs;
+    size_t structs_len;
+    const uint8_t* strings;
+    size_t strings_len;
+};
+
+struct fdt_node {
+    struct fdt* tree;
+};
+
+struct fdt_prop {
+    struct fdt* tree;
+};
+
+// Root of the device tree.
+struct fdt_node fdt_root(struct fdt* tree);
diff --git a/include/zinnia/ident.h b/include/zinnia/ident.h
index ed90f13..7fd3ee1 100644
--- a/include/zinnia/ident.h
+++ b/include/zinnia/ident.h
@@ -1,5 +1,13 @@
 #pragma once
 
+#include <zinnia/types.h>
+#include <zinnia/vec.h>
+
 struct ident {
-    // TODO
+    uid_t uid, euid, suid;
+    gid_t gid, egid, sgid;
+
+    vec(gid_t) groups;
 };
+
+const struct ident* ident_kernel(void);
diff --git a/include/zinnia/iovec.h b/include/zinnia/iovec.h
index 72d2e1a..fea7e4a 100644
--- a/include/zinnia/iovec.h
+++ b/include/zinnia/iovec.h
@@ -1,12 +1,37 @@
 #pragma once
 
+#include <zinnia/errno.h>
+#include <zinnia/string.h>
+#include <zinnia/usercopy.h>
+#include <zinnia/utils.h>
+#include <stddef.h>
 #include <uapi/uio.h>
 
 struct iovec_iter {
-    struct iovec* iovecs;
+    struct __iovec* iovecs;
     size_t iovecs_len;
     size_t total_len;
     size_t total_offset;
     size_t current_idx;
     size_t current_offset;
 };
+
+static inline size_t iovec_iter_len(struct iovec_iter* iter) {
+    return iter->total_len - iter->total_offset;
+}
+
+// Creates an iovec iterator over kernel memory.
+static inline struct iovec_iter iovec_iter_kernel(struct __iovec* iovecs, size_t count) {
+    size_t total = 0;
+    for (size_t i = 0; i < count; i++)
+        total += iovecs[i].len;
+
+    return (struct iovec_iter){
+        .iovecs = iovecs,
+        .iovecs_len = count,
+        .total_len = total,
+        .total_offset = 0,
+        .current_idx = 0,
+        .current_offset = 0,
+    };
+}
diff --git a/include/zinnia/spin.h b/include/zinnia/spin.h
index dfcc9f2..878afc0 100644
--- a/include/zinnia/spin.h
+++ b/include/zinnia/spin.h
@@ -10,6 +10,8 @@ struct spinlock {
     _Atomic(uint32_t) next;
 };
 
+void spin_init(struct spinlock* spin);
+
 // Attempts to lock a spinlock. If it's already locked, waits until it's freed.
 void spin_lock(struct spinlock* spin);
 
diff --git a/include/zinnia/vmo.h b/include/zinnia/vmo.h
index eea6465..15f879b 100644
--- a/include/zinnia/vmo.h
+++ b/include/zinnia/vmo.h
@@ -33,7 +33,7 @@ struct pager_ops {
     errno_t (*put_page)(struct pager_ops* pager, uintptr_t offset_idx, struct page* page);
 };
 
-// TODO: change to btree
+// TODO: change to rbtree
 struct page_list {
     uintptr_t offset;
     struct page* value;
@@ -50,5 +50,8 @@ struct paged_vmo {
 errno_t vmo_new_paged(struct pager_ops ops, struct paged_vmo** out);
 errno_t vmo_new_phys(struct paged_vmo** out);
 
+// Drops all cached pages past `length` bytes.
+void vmo_truncate_paged(struct paged_vmo* paged, size_t length);
+
 // Creates a VMO backed by a specific physical address range (e.g. for MMIO).
 errno_t vmo_new_phys_range(uintptr_t addr, size_t length, struct vmo** out);
diff --git a/syscalls/uname.c b/syscalls/uname.c
index f33bbb6..671da25 100644
--- a/syscalls/uname.c
+++ b/syscalls/uname.c
@@ -13,7 +13,7 @@ static struct __utsname uname_buf = {
     .version = CONFIG_KERNEL_FLAVOR,
     .nodename = "localhost",
     .machine = ZINNIA_ARCH,
-    .domainname = "none",
+    .domainname = "(none)",
 };
 
 struct syscall_ret sys_setuname(const __user struct __utsname* ptr) {