diff --git a/src/emu/emu_system.c b/src/emu/emu_system.c
new file mode 100644
index 0000000..8d78610
--- /dev/null
+++ b/src/emu/emu_system.c
@@ -0,0 +1,315 @@
+/* Copyright (c) 2021-2023 Barcelona Supercomputing Center (BSC)
+ * SPDX-License-Identifier: GPL-3.0-or-later */
+
+#include "emu_system.h"
+#include "utlist.h"
+
+static int
+has_prefix(const char *path, const char *prefix)
+{
+	if (strncmp(path, prefix, strlen(prefix)) != 0)
+		return 0;
+
+	return 1;
+}
+
+static struct emu_thread *
+new_thread(struct emu_proc *proc, const char *name, const char *relpath)
+{
+	struct emu_thread *thread = calloc(1, sizeof(struct emu_thread));
+
+	if (thread == NULL)
+		die("calloc failed\n");
+
+	if (snprintf(thread->name, PATH_MAX, "%s", name) >= PATH_MAX)
+		die("new_thread: name too long: %s\n", name);
+
+	if (snprintf(thread->relpath, PATH_MAX, "%s", relpath) >= PATH_MAX)
+		die("new_proc: relative path too long: %s\n", relpath);
+
+	thread->proc = proc;
+
+	err("new thread '%s'\n", thread->name);
+
+	return thread;
+}
+
+static struct emu_thread *
+find_thread(struct emu_proc *proc, const char *name)
+{
+	for (struct emu_thread *t = proc->threads; t; t = t->lnext) {
+		if (strcmp(t->name, name) == 0)
+			return t;
+	}
+	return NULL;
+}
+
+static int
+create_thread(struct emu_proc *proc, const char *relpath)
+{
+	char name[PATH_MAX];
+	if (snprintf(name, PATH_MAX, "%s", relpath) >= PATH_MAX) {
+		err("create_thread: path too long: %s\n", relpath);
+		return -1;
+	}
+
+	if (strtok(name, "/") == NULL) {
+		err("missing first slash\n");
+		return -1;
+	}
+
+	if (strtok(NULL, "/") == NULL) {
+		err("missing second slash\n");
+		return -1;
+	}
+
+	char *threadname = strtok(NULL, "/");
+	if (threadname == NULL) {
+		err("missing thread name\n");
+		return -1;
+	}
+
+	if (!has_prefix(threadname, "thread")) {
+		err("warning: ignoring unknown thread stream %s\n",
+				relpath);
+		return 0;
+	}
+
+	struct emu_thread *thread = find_thread(proc, threadname);
+
+	if (thread == NULL) {
+		thread = new_thread(proc, threadname, relpath);
+		DL_APPEND2(proc->threads, thread, lprev, lnext);
+		proc->nthreads++;
+	}
+
+	return 0;
+}
+
+static struct emu_proc *
+new_proc(struct emu_loom *loom, const char *name, const char *relpath)
+{
+	struct emu_proc *proc = calloc(1, sizeof(struct emu_proc));
+
+	if (proc == NULL)
+		die("calloc failed\n");
+
+	if (snprintf(proc->name, PATH_MAX, "%s", name) >= PATH_MAX)
+		die("new_proc: name too long: %s\n", name);
+
+	if (snprintf(proc->relpath, PATH_MAX, "%s", relpath) >= PATH_MAX)
+		die("new_proc: relative path too long: %s\n", relpath);
+
+	proc->loom = loom;
+
+	err("new proc '%s'\n", proc->name);
+
+	return proc;
+}
+
+static struct emu_proc *
+find_proc(struct emu_loom *loom, const char *name)
+{
+	for (struct emu_proc *proc = loom->procs; proc; proc = proc->lnext) {
+		if (strcmp(proc->name, name) == 0)
+			return proc;
+	}
+	return NULL;
+}
+
+static int
+create_proc(struct emu_loom *loom, const char *relpath)
+{
+	char name[PATH_MAX];
+	if (snprintf(name, PATH_MAX, "%s", relpath) >= PATH_MAX) {
+		err("create_proc: path too long: %s\n", relpath);
+		return -1;
+	}
+
+	if (strtok(name, "/") == NULL) {
+		err("missing first slash\n");
+		return -1;
+	}
+
+	char *procname = strtok(NULL, "/");
+	if (procname == NULL) {
+		err("missing proc name\n");
+		return -1;
+	}
+
+	if (!has_prefix(procname, "proc")) {
+		err("warning: ignoring unknown proc stream %s\n",
+				relpath);
+		return 0;
+	}
+
+	struct emu_proc *proc = find_proc(loom, procname);
+
+	if (proc == NULL) {
+		proc = new_proc(loom, procname, relpath);
+		DL_APPEND2(loom->procs, proc, lprev, lnext);
+		loom->nprocs++;
+	}
+
+	return create_thread(proc, relpath);
+}
+
+static struct emu_loom *
+find_loom(struct emu_system *sys, const char *name)
+{
+	for (struct emu_loom *loom = sys->looms; loom; loom = loom->next) {
+		if (strcmp(loom->name, name) == 0)
+			return loom;
+	}
+	return NULL;
+}
+
+static struct emu_loom *
+new_loom(const char *name, const char *relpath)
+{
+	struct emu_loom *loom = calloc(1, sizeof(struct emu_loom));
+
+	if (loom == NULL)
+		die("calloc failed\n");
+
+	if (snprintf(loom->name, PATH_MAX, "%s", name) >= PATH_MAX)
+		die("new_loom: name too long: %s\n", name);
+
+	if (snprintf(loom->relpath, PATH_MAX, "%s", relpath) >= PATH_MAX)
+		die("new_loom: relative path too long: %s\n", relpath);
+
+	err("new loom '%s'\n", loom->name);
+
+	return loom;
+}
+
+static int
+create_loom(struct emu_system *sys, const char *relpath)
+{
+	char name[PATH_MAX];
+	if (snprintf(name, PATH_MAX, "%s", relpath) >= PATH_MAX) {
+		err("create_loom: path too long: %s\n", relpath);
+		return -1;
+	}
+
+	if (strtok(name, "/") == NULL) {
+		err("create_looms: cannot find first '/': %s\n",
+				relpath);
+		return -1;
+	}
+	
+	struct emu_loom *loom = find_loom(sys, name);
+
+	if (loom == NULL) {
+		loom = new_loom(name, relpath);
+		DL_APPEND(sys->looms, loom);
+		sys->nlooms++;
+	}
+
+	return create_proc(loom, relpath);
+}
+
+static int
+create_system(struct emu_system *sys, struct emu_trace *trace)
+{
+	for (struct emu_stream *s = trace->streams; s ; s = s->next) {
+		if (!has_prefix(s->relpath, "loom")) {
+			err("warning: ignoring unknown steam %s\n",
+					s->relpath);
+			continue;
+		}
+
+		if (create_loom(sys, s->relpath) != 0) {
+			err("create loom failed\n");
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static int
+cmp_thread(struct emu_thread *a, struct emu_thread *b)
+{
+	return strcmp(a->name, b->name);
+}
+
+static void
+sort_proc(struct emu_proc *proc)
+{
+	DL_SORT2(proc->threads, cmp_thread, lprev, lnext);
+}
+
+static int
+cmp_proc(struct emu_proc *a, struct emu_proc *b)
+{
+	return strcmp(a->name, b->name);
+}
+
+static void
+sort_loom(struct emu_loom *loom)
+{
+	DL_SORT2(loom->procs, cmp_proc, lprev, lnext);
+
+	for (struct emu_proc *p = loom->procs; p; p = p->gnext)
+		sort_proc(p);
+}
+
+static int
+cmp_loom(struct emu_loom *a, struct emu_loom *b)
+{
+	return strcmp(a->name, b->name);
+}
+
+static void
+sort_system(struct emu_system *sys)
+{
+	DL_SORT(sys->looms, cmp_loom);
+
+	for (struct emu_loom *l = sys->looms; l; l = l->next)
+		sort_loom(l);
+}
+
+static void
+populate_global_lists(struct emu_system *sys)
+{
+	for (struct emu_loom *l = sys->looms; l; l = l->next) {
+		for (struct emu_proc *p = l->procs; p; p = p->lnext) {
+			for (struct emu_thread *t = p->threads; t; t = t->lnext) {
+				DL_APPEND2(sys->threads, t, gprev, gnext);
+			}
+			DL_APPEND2(sys->procs, p, gprev, gnext);
+		}
+		/* Looms are already in emu_system */
+	}
+}
+
+static void
+print_system(struct emu_system *sys)
+{
+	err("content of system:\n");
+	for (struct emu_loom *l = sys->looms; l; l = l->next) {
+		err("%s\n", l->name);
+		for (struct emu_proc *p = l->procs; p; p = p->lnext) {
+			err("  %s\n", p->name);
+			for (struct emu_thread *t = p->threads; t; t = t->lnext) {
+				err("    %s\n", t->name);
+			}
+		}
+	}
+}
+
+int
+emu_system_load(struct emu_system *sys, struct emu_trace *trace)
+{
+	if (create_system(sys, trace) != 0) {
+		err("emu_system_load: create system failed\n");
+		return -1;
+	}
+
+	sort_system(sys);
+	populate_global_lists(sys);
+	print_system(sys);
+
+	return 0;
+}
diff --git a/src/emu/emu_system.h b/src/emu/emu_system.h
new file mode 100644
index 0000000..11dad2a
--- /dev/null
+++ b/src/emu/emu_system.h
@@ -0,0 +1,189 @@
+/* Copyright (c) 2021-2023 Barcelona Supercomputing Center (BSC)
+ * SPDX-License-Identifier: GPL-3.0-or-later */
+
+#ifndef EMU_SYSTEM_H
+#define EMU_SYSTEM_H
+
+#include "emu_trace.h"
+#include "parson.h"
+#include "ovni.h"
+#include <stddef.h>
+
+#define MAX_CPU_NAME 32
+
+struct emu_cpu;
+struct emu_thread;
+struct emu_proc;
+struct emu_loom;
+struct emu_system;
+
+enum emu_cpu_state {
+	CPU_ST_UNKNOWN,
+	CPU_ST_READY,
+};
+
+#define MAX_MODELS 256
+
+struct model_ctx {
+	void *data[MAX_MODELS];
+};
+
+struct emu_cpu {
+	/* Logical index: 0 to ncpus - 1 */
+	int i;
+
+	/* Physical id: as reported by lscpu(1) */
+	int phyid;
+
+	/* Global index for all CPUs */
+	int gindex;
+
+	enum emu_cpu_state state;
+
+	/* The loom of the CPU */
+	struct emu_loom *loom;
+
+	size_t nthreads;
+	struct emu_thread *thread; /* List of threads assigned to this CPU */
+
+	size_t nrunning_threads;
+	struct emu_thread *th_running; /* One */
+
+	size_t nactive_threads;
+	struct emu_thread *th_active;
+
+	/* Is this a virtual CPU? */
+	int virtual;
+
+	/* Global list */
+	struct emu_cpu *next;
+	struct emu_cpu *prev;
+
+	struct model_ctx ctx;
+};
+
+/* Emulated thread runtime status */
+enum emu_thread_state {
+	TH_ST_UNKNOWN,
+	TH_ST_RUNNING,
+	TH_ST_PAUSED,
+	TH_ST_DEAD,
+	TH_ST_COOLING,
+	TH_ST_WARMING,
+};
+
+struct emu_thread {
+	char name[PATH_MAX];
+	char relpath[PATH_MAX];
+
+	int tid;
+	int index; /* In loom */
+	int gindex; /* In emu */
+
+	/* The process associated with this thread */
+	struct emu_proc *proc;
+
+	enum emu_thread_state state;
+	int is_running;
+	int is_active;
+
+	/* Current cpu, NULL if not unique affinity */
+	struct emu_cpu *cpu;
+
+	/* Linked list of threads in each CPU */
+	struct emu_thread *cpu_prev;
+	struct emu_thread *cpu_next;
+
+	/* Local list */
+	struct emu_thread *lprev;
+	struct emu_thread *lnext;
+
+	/* Global list */
+	struct emu_thread *gnext;
+	struct emu_thread *gprev;
+
+	struct model_ctx ctx;
+};
+
+/* State of each emulated process */
+struct emu_proc {
+	char name[PATH_MAX]; /* Proc directory name */
+	char relpath[PATH_MAX];
+
+	int pid;
+	int index;
+	int gindex;
+	int appid;
+	int rank;
+
+	struct emu_loom *loom;
+
+	JSON_Value *meta;
+
+	int nthreads;
+	struct emu_thread *threads;
+
+	/* Local list */
+	struct emu_proc *lnext;
+	struct emu_proc *lprev;
+
+	/* Global list */
+	struct emu_proc *gnext;
+	struct emu_proc *gprev;
+
+	struct model_ctx ctx;
+};
+
+struct emu_loom {
+	char hostname[OVNI_MAX_HOSTNAME];
+	char name[PATH_MAX]; /* Loom directory name */
+	char relpath[PATH_MAX];  /* Relative to tracedir */
+
+	size_t max_ncpus;
+	size_t max_phyid;
+	size_t ncpus;
+	size_t offset_ncpus;
+	struct emu_cpu *cpu;
+	int rank_enabled;
+
+	int64_t clock_offset;
+
+	/* Virtual CPU */
+	struct emu_cpu vcpu;
+
+	/* Local list */
+	size_t nprocs;
+	struct emu_proc *procs;
+
+	/* Global list */
+	struct emu_loom *next;
+	struct emu_loom *prev;
+
+	struct model_ctx ctx;
+};
+
+struct emu_system {
+	size_t nlooms;
+	size_t nthreads;
+	size_t nprocs;
+	size_t ncpus; /* Physical */
+
+	struct emu_loom *looms;
+	struct emu_proc *procs;
+	struct emu_thread *threads;
+	struct emu_cpu *cpus;
+
+	/* From current event */
+	struct emu_loom *cur_loom;
+	struct emu_proc *cur_proc;
+	struct emu_thread *cur_thread;
+
+	struct model_ctx ctx;
+};
+
+int emu_system_load(struct emu_system *system, struct emu_trace *trace);
+
+int model_ctx_set(struct model_ctx *ctx, int model, void *data);
+int model_ctx_get(struct model_ctx *ctx, int model, void *data);
+
+#endif /* EMU_SYSTEM_H */