[kernel] Let endpoints get interrupt notifications

- Add a tag field to all endpoint messages, which doubles as a
  notification field
- Add a endpoint_bind_irq syscall to enable an endpoint to listen for
  interrupt notifications. This mechanism needs to change.
- Add a temporary copy of the serial port code to nulldrv, and let it
  take responsibility for COM2

modules.yaml

@@ -83,8 +83,10 @@ modules:
         deps:
           - libc
         source:
+            - src/drivers/nulldrv/io.cpp
             - src/drivers/nulldrv/main.cpp
             - src/drivers/nulldrv/main.s
+            - src/drivers/nulldrv/serial.cpp
 
     kutil:
         kind: lib

qemu.sh

@@ -45,6 +45,8 @@ if [[ -n $TMUX ]]; then
 	if [[ -n $debug ]]; then
 		tmux split-window -h "gdb ${debugtarget}" &
 	else
+		tmux split-window -h -l 80 "sleep 1; telnet localhost 45455" &
+		tmux last-pane
 		tmux split-window -l 10 "sleep 1; telnet localhost 45454" &
 	fi
 elif [[ $DESKTOP_SESSION = "i3" ]]; then
@@ -61,6 +63,8 @@ exec qemu-system-x86_64 \
 	-drive "format=raw,file=${build}/jsix.img" \
 	-device "isa-debug-exit,iobase=0xf4,iosize=0x04" \
 	-monitor telnet:localhost:45454,server,nowait \
+	-serial stdio \
+	-serial telnet:localhost:45455,server,nowait \
 	-smp 4 \
 	-m 512 \
 	-d mmu,int,guest_errors \

src/boot/main.cpp

@@ -37,7 +37,7 @@ struct program_desc
 const program_desc program_list[] = {
 	{L"kernel", L"jsix.elf"},
 	{L"null driver", L"nulldrv.elf"},
-	{L"terminal driver", L"terminal.elf"},
+	//{L"terminal driver", L"terminal.elf"},
 };
 
 /// Change a pointer to point to the higher-half linear-offset version

src/drivers/nulldrv/io.cpp

@@ -0,0 +1,22 @@
+#include "io.h"
+
+uint8_t
+inb(uint16_t port)
+{
+	uint8_t val;
+	__asm__ __volatile__ ( "inb %1, %0" : "=a"(val) : "Nd"(port) );
+	return val;
+}
+
+void
+outb(uint16_t port, uint8_t val)
+{
+	__asm__ __volatile__ ( "outb %0, %1" :: "a"(val), "Nd"(port) );
+}
+
+void
+io_wait(unsigned times)
+{
+	for (unsigned i = 0; i < times; ++i)
+		outb(0x80, 0);
+}

src/drivers/nulldrv/io.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <stdint.h>
+
+extern "C" {
+
+/// Read a byte from an IO port.
+/// \arg port  The address of the IO port
+/// \returns   One byte read from the port
+uint8_t inb(uint16_t port);
+
+/// Write a byte to an IO port.
+/// \arg port  The addres of the IO port
+/// \arg val   The byte to write
+void outb(uint16_t port, uint8_t val);
+
+/// Pause briefly by doing IO to port 0x80
+/// \arg times  Number of times to delay by writing
+void io_wait(unsigned times = 1);
+
+}
+
+constexpr uint16_t COM1 = 0x03f8;
+constexpr uint16_t COM2 = 0x02f8;

src/drivers/nulldrv/main.cpp

@@ -7,6 +7,9 @@
 
 #include <j6libc/syscalls.h>
 
+#include "io.h"
+#include "serial.h"
+
 char inbuf[1024];
 j6_handle_t endp = j6_handle_invalid;
 
@@ -24,7 +27,8 @@ thread_proc()
 
 	char buffer[512];
 	size_t len = sizeof(buffer);
-	j6_status_t result = _syscall_endpoint_receive(endp, &len, (void*)buffer);
+	j6_tag_t tag = 0;
+	j6_status_t result = _syscall_endpoint_receive(endp, &tag, &len, (void*)buffer);
 	if (result != j6_status_ok)
 		_syscall_thread_exit(result);
 
@@ -34,7 +38,8 @@ thread_proc()
 		if (buffer[i] >= 'A' && buffer[i] <= 'Z')
 			buffer[i] += 0x20;
 
-	result = _syscall_endpoint_send(endp, len, (void*)buffer);
+	tag++;
+	result = _syscall_endpoint_send(endp, tag, len, (void*)buffer);
 	if (result != j6_status_ok)
 		_syscall_thread_exit(result);
 
@@ -66,8 +71,8 @@ main(int argc, const char **argv)
 		return 1;
 
 	uint64_t *vma_ptr = reinterpret_cast<uint64_t*>(base);
-	for (int i = 0; i < 300; ++i)
+	for (int i = 0; i < 3; ++i)
-		vma_ptr[i] = uint64_t(i);
+		vma_ptr[i*100] = uint64_t(i);
 
 	_syscall_system_log("main thread wrote to memory area");
 
@@ -85,10 +90,14 @@ main(int argc, const char **argv)
 
 	char message[] = "MAIN THREAD SUCCESSFULLY CALLED SENDRECV IF THIS IS LOWERCASE";
 	size_t size = sizeof(message);
-	result = _syscall_endpoint_sendrecv(endp, &size, (void*)message);
+	j6_tag_t tag = 16;
+	result = _syscall_endpoint_sendrecv(endp, &tag, &size, (void*)message);
 	if (result != j6_status_ok)
 		return result;
 
+	if (tag != 17)
+		_syscall_system_log("GOT WRONG TAG FROM SENDRECV");
+
 	_syscall_system_log(message);
 
 	_syscall_system_log("main thread waiting on child");
@@ -97,6 +106,29 @@ main(int argc, const char **argv)
 	if (result != j6_status_ok)
 		return result;
 
+	_syscall_system_log("main testing irqs");
+
+	_syscall_endpoint_bind_irq(endp, 3);
+
+	serial_port com2(COM2);
+
+	const char *fgseq = "\x1b[2J";
+	while (*fgseq)
+		com2.write(*fgseq++);
+
+	for (int i = 0; i < 10; ++i)
+		com2.write('%');
+
+	size_t len = 0;
+	while (true) {
+		result = _syscall_endpoint_receive(endp, &tag, &len, nullptr);
+		if (result != j6_status_ok)
+			return result;
+
+		if (j6_tag_is_irq(tag))
+			_syscall_system_log("main thread got irq!");
+	}
+
 	_syscall_system_log("main thread closing endpoint");
 
 	result = _syscall_endpoint_close(endp);

src/drivers/nulldrv/serial.cpp

@@ -0,0 +1,41 @@
+#include "io.h"
+#include "serial.h"
+
+
+serial_port::serial_port() :
+	m_port(0)
+{
+}
+
+serial_port::serial_port(uint16_t port) :
+	m_port(port)
+{
+	outb(port + 1, 0x00);  // Disable all interrupts
+	outb(port + 3, 0x80);  // Enable the Divisor Latch Access Bit
+	outb(port + 0, 0x01);  // Divisor low bit: 1 (115200 baud)
+	outb(port + 1, 0x00);  // Divisor high bit
+	outb(port + 3, 0x03);  // 8-N-1
+	outb(port + 2, 0xe7);  // Clear and enable FIFO, enable 64 byte, 56 byte trigger
+	outb(port + 4, 0x0b);  // Data terminal ready, Request to send, aux output 2 (irq enable)
+	outb(port + 1, 0x03);  // Enable interrupts
+}
+
+bool serial_port::read_ready() { return (inb(m_port + 5) & 0x01) != 0; }
+
+bool serial_port::write_ready() {
+	uint8_t lsr = inb(m_port + 5);
+	return (lsr & 0x20) != 0;
+}
+
+char
+serial_port::read() {
+	while (!read_ready());
+	return inb(m_port);
+}
+
+void
+serial_port::write(char c) {
+	while (!write_ready());
+	outb(m_port, c);
+}
+

src/drivers/nulldrv/serial.h

@@ -0,0 +1,26 @@
+#pragma once
+/// \file serial.h
+/// Declarations related to serial ports.
+#include <stdint.h>
+
+#define serial_port nulldrv_serial_port
+
+class serial_port
+{
+public:
+	/// Constructor.
+	/// \arg port   The IO address of the serial port
+	serial_port(uint16_t port);
+
+	serial_port();
+
+	void write(char c);
+	char read();
+
+private:
+	uint16_t m_port;
+
+	bool read_ready();
+	bool write_ready();
+};
+

src/include/j6/types.h

@@ -10,16 +10,30 @@ typedef uint64_t j6_koid_t;
 /// Syscalls return status as this type
 typedef uint64_t j6_status_t;
 
-/// Handles are references and capabilities to other objects
-typedef uint32_t j6_handle_t;
-
 /// Some objects have signals, which are a bitmap of 64 possible signals
 typedef uint64_t j6_signal_t;
 
-/// The rights of a handle/capability are a bitmap of 64 possible rights
+/// The first word of IPC messages are the tag. Tags with the high bit
-typedef uint64_t j6_rights_t;
+/// set are reserved for the system.
+typedef uint64_t j6_tag_t;
 
-#define j6_handle_invalid 0xffffffff
+#define j6_tag_system_flag    0x8000000000000000
+
+/// If all high bits except the last 16 are set, then the tag represents
+/// an IRQ.
+#define j6_tag_irq_base       0xffffffffffff0000
+#define j6_tag_is_irq(x)      (((x) & j6_tag_irq_base) == j6_tag_irq_base)
+#define j6_tag_from_irq(x)    ((x) | j6_tag_irq_base)
+#define j6_tag_to_irq(x)      ((x) & ~j6_tag_irq_base)
+
+/// Handles are references and capabilities to other objects. The least
+/// significant 32 bits are an identifier, and the most significant 32
+/// bits are a bitmask of capabilities this handle has on that object.
+typedef uint64_t j6_handle_t;
+
+#define j6_handle_rights_shift 4
+#define j6_handle_id_mask 0xffffffffull
+#define j6_handle_invalid 0xffffffffull
 
 /// A process' initial data structure for communicating with the system
 struct j6_process_init

src/include/syscalls.inc

@@ -20,9 +20,10 @@ SYSCALL(0x23, channel_receive,   j6_handle_t, size_t *, void *)
 
 SYSCALL(0x28, endpoint_create,   j6_handle_t *)
 SYSCALL(0x29, endpoint_close,    j6_handle_t)
-SYSCALL(0x2a, endpoint_send,     j6_handle_t, size_t, void *)
+SYSCALL(0x2a, endpoint_send,     j6_handle_t, j6_tag_t, size_t, void *)
-SYSCALL(0x2b, endpoint_receive,  j6_handle_t, size_t *, void *)
+SYSCALL(0x2b, endpoint_receive,  j6_handle_t, j6_tag_t *, size_t *, void *)
-SYSCALL(0x2c, endpoint_sendrecv, j6_handle_t, size_t *, void *)
+SYSCALL(0x2c, endpoint_sendrecv, j6_handle_t, j6_tag_t *, size_t *, void *)
+SYSCALL(0x2d, endpoint_bind_irq, j6_handle_t, unsigned)
 
 SYSCALL(0x30, vma_create,        j6_handle_t *, size_t, uint32_t)
 SYSCALL(0x31, vma_create_map,    j6_handle_t *, size_t, uintptr_t, uint32_t)

src/kernel/device_manager.cpp

@@ -11,8 +11,11 @@
 #include "interrupts.h"
 #include "kernel_memory.h"
 #include "log.h"
+#include "objects/endpoint.h"
 
 
+static endpoint * const ignore_endpoint = reinterpret_cast<endpoint*>(-1ull);
+
 static const char expected_signature[] = "RSD PTR ";
 
 device_manager device_manager::s_instance;
@@ -64,8 +67,7 @@ device_manager::device_manager() :
 {
 	m_irqs.ensure_capacity(32);
 	m_irqs.set_size(16);
-	m_irqs[2] = {"Clock interrupt", irq2_callback, nullptr};
+	m_irqs[2] = ignore_endpoint;
-	m_irqs[4] = {"Serial interrupt", irq4_callback, nullptr};
 }
 
 void
@@ -339,35 +341,44 @@ device_manager::init_drivers()
 }
 
 bool
-device_manager::install_irq(unsigned irq, const char *name, irq_callback cb, void *data)
+device_manager::dispatch_irq(unsigned irq)
 {
 	if (irq >= m_irqs.count())
-		m_irqs.set_size(irq+1);
-
-	if (m_irqs[irq].callback != nullptr)
 		return false;
 
-	m_irqs[irq] = {name, cb, data};
+	endpoint *e = m_irqs[irq];
+	if (!e || e == ignore_endpoint)
+		return e == ignore_endpoint;
+
+	e->signal_irq(irq);
 	return true;
 }
 
 bool
-device_manager::uninstall_irq(unsigned irq, irq_callback cb, void *data)
+device_manager::bind_irq(unsigned irq, endpoint *target)
 {
+	// TODO: grow if under max size
 	if (irq >= m_irqs.count())
 		return false;
 
-	const irq_allocation &existing = m_irqs[irq];
+	m_irqs[irq]= target;
-	if (existing.callback != cb || existing.data != data)
-		return false;
-
-	m_irqs[irq] = {nullptr, nullptr, nullptr};
 	return true;
 }
 
+void
+device_manager::unbind_irqs(endpoint *target)
+{
+	const size_t count = m_irqs.count();
+	for (size_t i = 0; i < count; ++i) {
+		if (m_irqs[i] == target)
+			m_irqs[i] = nullptr;
+	}
+}
+
 bool
 device_manager::allocate_msi(const char *name, pci_device &device, irq_callback cb, void *data)
 {
+	/*
 	// TODO: find gaps to fill
 	uint8_t irq = m_irqs.count();
 	isr vector = isr::irq00 + irq;
@@ -378,6 +389,7 @@ device_manager::allocate_msi(const char *name, pci_device &device, irq_callback
 	device.write_msi_regs(
 			0xFEE00000,
 			static_cast<uint16_t>(vector));
+	*/
 	return true;
 }
 

src/kernel/device_manager.h

@@ -11,6 +11,7 @@ struct acpi_apic;
 struct acpi_mcfg;
 struct acpi_hpet;
 class block_device;
+class endpoint;
 
 using irq_callback = void (*)(void *);
 
@@ -43,27 +44,15 @@ public:
 	/// Intialize drivers for the current device list.
 	void init_drivers();
 
-	/// Install an IRQ callback for a device
+	/// Bind an IRQ to an endpoint
-	/// \arg irq   IRQ to install the handler for
+	/// \arg irq    The IRQ number to bind
-	/// \arg name  Name of the interrupt, for display to user
+	/// \arg target The endpoint to recieve messages when the IRQ is signalled
-	/// \arg cb    Callback to call when the interrupt is received
+	/// \returns    True on success
-	/// \arg data  Data to pass to the callback
+	bool bind_irq(unsigned irq, endpoint *target);
-	/// \returns   True if an IRQ was installed successfully
-	bool install_irq(
-			unsigned irq,
-			const char *name,
-			irq_callback cb,
-			void *data);
 
-	/// Uninstall an IRQ callback for a device
+	/// Remove IRQ bindings for an endpoint
-	/// \arg irq   IRQ to install the handler for
+	/// \arg target The endpoint to remove
-	/// \arg cb    Callback to call when the interrupt is received
+	void unbind_irqs(endpoint *target);
-	/// \arg data  Data to pass to the callback
-	/// \returns   True if an IRQ was uninstalled successfully
-	bool uninstall_irq(
-			unsigned irq,
-			irq_callback cb,
-			void *data);
 
 	/// Allocate an MSI IRQ for a device
 	/// \arg name    Name of the interrupt, for display to user
@@ -80,17 +69,7 @@ public:
 	/// Dispatch an IRQ interrupt
 	/// \arg irq  The irq number of the interrupt
 	/// \returns  True if the interrupt was handled
-	inline bool dispatch_irq(uint8_t irq)
+	bool dispatch_irq(unsigned irq);
-	{
-		if (irq < m_irqs.count()) {
-			irq_allocation &cba = m_irqs[irq];
-			if (cba.callback) {
-				cba.callback(cba.data);
-				return true;
-			}
-		}
-		return false;
-	}
 
 	/// Register the existance of a block device.
 	/// \arg blockdev  Pointer to the block device
@@ -150,13 +129,7 @@ private:
 	kutil::vector<pci_group> m_pci;
 	kutil::vector<pci_device> m_devices;
 
-	struct irq_allocation
+	kutil::vector<endpoint*> m_irqs;
-	{
-		const char *name = nullptr;
-		irq_callback callback = nullptr;
-		void *data = nullptr;
-	};
-	kutil::vector<irq_allocation> m_irqs;
 
 	kutil::vector<block_device *> m_blockdevs;
 

src/kernel/interrupts.cpp

@@ -84,13 +84,6 @@ disable_legacy_pic()
 	outb(PIC2+1, 0x02); io_wait();
 }
 
-static void
-enable_serial_interrupts()
-{
-	uint8_t ier = inb(COM1+1);
-	outb(COM1+1, ier | 0x1);
-}
-
 void
 interrupts_init()
 {
@@ -105,7 +98,6 @@ interrupts_init()
 #undef ISR
 
 	disable_legacy_pic();
-	enable_serial_interrupts();
 
 	log::info(logs::boot, "Interrupts enabled.");
 }

src/kernel/main.cpp

@@ -17,7 +17,6 @@
 #include "log.h"
 #include "objects/channel.h"
 #include "objects/event.h"
-#include "objects/handle.h"
 #include "scheduler.h"
 #include "serial.h"
 #include "symbol_table.h"

src/kernel/objects/endpoint.cpp

@@ -1,10 +1,11 @@
+#include "device_manager.h"
 #include "objects/endpoint.h"
 #include "objects/process.h"
 #include "objects/thread.h"
 #include "vm_space.h"
 
 endpoint::endpoint() :
-	kobject(kobject::type::endpoint)
+	kobject {kobject::type::endpoint}
 {}
 
 endpoint::~endpoint()
@@ -17,15 +18,20 @@ void
 endpoint::close()
 {
 	assert_signal(j6_signal_endpoint_closed);
-	for (auto &data : m_blocked)
+	for (auto &data : m_blocked) {
-		data.th->wake_on_result(this, j6_status_closed);
+		if (data.th)
+			data.th->wake_on_result(this, j6_status_closed);
+	}
+
+	device_manager::get().unbind_irqs(this);
 }
 
 j6_status_t
-endpoint::send(size_t len, void *data)
+endpoint::send(j6_tag_t tag, size_t len, void *data)
 {
 	thread_data sender = { &thread::current(), data };
 	sender.len = len;
+	sender.tag = tag;
 
 	if (!check_signal(j6_signal_endpoint_can_send)) {
 		assert_signal(j6_signal_endpoint_can_recv);
@@ -48,9 +54,10 @@ endpoint::send(size_t len, void *data)
 }
 
 j6_status_t
-endpoint::receive(size_t *len, void *data)
+endpoint::receive(j6_tag_t *tag, size_t *len, void *data)
 {
 	thread_data receiver = { &thread::current(), data };
+	receiver.tag_p = tag;
 	receiver.len_p = len;
 
 	if (!check_signal(j6_signal_endpoint_can_recv)) {
@@ -69,20 +76,54 @@ endpoint::receive(size_t *len, void *data)
 
 	// TODO: don't pop sender on some errors
 	j6_status_t status = do_message_copy(sender, receiver);
-	sender.th->wake_on_result(this, status);
+
+	if (sender.th)
+		sender.th->wake_on_result(this, status);
+
 	return status;
 }
 
+void
+endpoint::signal_irq(unsigned irq)
+{
+	j6_tag_t tag = j6_tag_from_irq(irq);
+
+	if (!check_signal(j6_signal_endpoint_can_send)) {
+		assert_signal(j6_signal_endpoint_can_recv);
+
+		for (auto &blocked : m_blocked)
+			if (blocked.tag == tag)
+				return;
+
+		thread_data sender = { nullptr, nullptr };
+		sender.tag = tag;
+		m_blocked.append(sender);
+		return;
+	}
+
+	thread_data receiver = m_blocked.pop_front();
+	if (m_blocked.count() == 0)
+		deassert_signal(j6_signal_endpoint_can_send);
+
+	*receiver.len_p = 0;
+	*receiver.tag_p = tag;
+	receiver.th->wake_on_result(this, j6_status_ok);
+}
+
 j6_status_t
 endpoint::do_message_copy(const endpoint::thread_data &sender, endpoint::thread_data &receiver)
 {
 	if (sender.len > *receiver.len_p)
 		return j6_err_insufficient;
 
-	vm_space &source = sender.th->parent().space();
+	if (sender.len) {
-	vm_space &dest = receiver.th->parent().space();
+		vm_space &source = sender.th->parent().space();
-	vm_space::copy(source, dest, sender.data, receiver.data, sender.len);
+		vm_space &dest = receiver.th->parent().space();
+		vm_space::copy(source, dest, sender.data, receiver.data, sender.len);
+	}
+
 	*receiver.len_p = sender.len;
+	*receiver.tag_p = sender.tag;
 
 	// TODO: this will not work if non-contiguous pages are mapped!!
 

src/kernel/objects/endpoint.h

@@ -26,23 +26,33 @@ public:
 
 	/// Send a message to a thread waiting to receive on this endpoint. If no threads
 	/// are currently trying to receive, block the current thread.
+	/// \arg tag   The application-specified message tag
 	/// \arg len   The size in bytes of the message
 	/// \arg data  The message data
 	/// \returns   j6_status_ok on success
-	j6_status_t send(size_t len, void *data);
+	j6_status_t send(j6_tag_t tag, size_t len, void *data);
 
 	/// Receive a message from a thread waiting to send on this endpoint. If no threads
 	/// are currently trying to send, block the current thread.
+	/// \arg tag   [in] The sender-specified message tag
 	/// \arg len   [in] The size in bytes of the buffer [out] Number of bytes in the message
 	/// \arg data  Buffer for copying message data into
 	/// \returns   j6_status_ok on success
-	j6_status_t receive(size_t *len, void *data);
+	j6_status_t receive(j6_tag_t *tag, size_t *len, void *data);
+
+	/// Give the listener on the endpoint a message that a bound IRQ has been signalled
+	/// \arg irq  The IRQ that caused this signal
+	void signal_irq(unsigned irq);
 
 private:
 	struct thread_data
 	{
 		thread *th;
 		void *data;
+		union {
+			j6_tag_t *tag_p;
+			j6_tag_t tag;
+		};
 		union {
 			size_t *len_p;
 			size_t len;

src/kernel/objects/handle.cpp

@@ -1,26 +0,0 @@
-#include "objects/handle.h"
-
-handle::handle(handle&& other) :
-	m_owner(other.m_owner),
-	m_object(other.m_object),
-	m_rights(other.m_rights)
-{
-	other.m_owner = 0;
-	other.m_object = nullptr;
-	other.m_rights = 0;
-}
-
-handle::handle(j6_koid_t owner, j6_rights_t rights, kobject *obj) :
-	m_owner(owner),
-	m_object(obj),
-	m_rights(rights)
-{
-	if (m_object)
-		m_object->handle_retain();
-}
-
-handle::~handle()
-{
-	if (m_object)
-		m_object->handle_release();
-}

src/kernel/objects/handle.h

@@ -1,30 +0,0 @@
-#pragma once
-/// \file handle.h
-/// Defines types for user handles to kernel objects
-
-#include "j6/types.h"
-#include "objects/kobject.h"
-
-class handle
-{
-public:
-	/// Move constructor. Takes ownership of the object from other.
-	handle(handle&& other);
-
-	/// Constructor.
-	/// \arg owner   koid of the process that has this handle
-	/// \arg rights  access rights this handle has over the object
-	/// \arg obj     the object held
-	handle(j6_koid_t owner, j6_rights_t rights, kobject *obj);
-
-	~handle();
-
-	handle() = delete;
-	handle(const handle &other) = delete;
-	handle & operator=(const handle& other) = delete;
-
-private:
-	j6_koid_t m_owner;
-	kobject *m_object;
-	j6_rights_t m_rights;
-};

src/kernel/scheduler.cpp

@@ -131,7 +131,7 @@ scheduler::load_process(uintptr_t phys, uintptr_t virt, size_t size, uintptr_t e
 	// Arguments for iret - rip will be pushed on before these
 	stack[4] = reinterpret_cast<uintptr_t>(entry);
 	stack[5] = cs;
-	stack[6] = rflags_int;
+	stack[6] = rflags_int | (3 << 12);
 	stack[7] = process::stacks_top;
 	stack[8] = ss;
 

src/kernel/serial.cpp

@@ -1,8 +1,12 @@
+#include "kutil/no_construct.h"
 #include "io.h"
 #include "serial.h"
 
-serial_port g_com1(COM1);
+// This object is initialized _before_ global constructors are called,
-
+// so we don't want it to have global constructors at all, lest it
+// overwrite the previous initialization.
+static kutil::no_construct<serial_port> __g_com1_storage;
+serial_port &g_com1 = __g_com1_storage.value;
 
 serial_port::serial_port() :
 	m_port(0)
@@ -12,6 +16,13 @@ serial_port::serial_port() :
 serial_port::serial_port(uint16_t port) :
 	m_port(port)
 {
+	outb(port + 1, 0x00);  // Disable all interrupts
+	outb(port + 3, 0x80);  // Enable the Divisor Latch Access Bit
+	outb(port + 0, 0x01);  // Divisor low bit: 1 (115200 baud)
+	outb(port + 1, 0x00);  // Divisor high bit
+	outb(port + 3, 0x03);  // 8-N-1
+	outb(port + 2, 0xe7);  // Clear and enable FIFO, enable 64 byte, 56 byte trigger
+	outb(port + 4, 0x0b);  // Data terminal ready, Request to send, aux output 2 (irq enable)
 }
 
 bool serial_port::read_ready() { return (inb(m_port + 5) & 0x01) != 0; }

src/kernel/serial.h

@@ -22,4 +22,4 @@ private:
 	bool write_ready();
 };
 
-extern serial_port g_com1;
+extern serial_port &g_com1;

src/kernel/syscalls/endpoint.cpp

@@ -2,6 +2,7 @@
 #include "j6/types.h"
 
 #include "log.h"
+#include "device_manager.h"
 #include "objects/endpoint.h"
 #include "syscalls/helpers.h"
 
@@ -24,32 +25,55 @@ endpoint_close(j6_handle_t handle)
 }
 
 j6_status_t
-endpoint_send(j6_handle_t handle, size_t len, void *data)
+endpoint_send(j6_handle_t handle, j6_tag_t tag, size_t len, void *data)
 {
+	if (tag & j6_tag_system_flag)
+		return j6_err_invalid_arg;
+
 	endpoint *e = get_handle<endpoint>(handle);
 	if (!e) return j6_err_invalid_arg;
-	return e->send(len, data);
+
+	return e->send(tag, len, data);
 }
 
 j6_status_t
-endpoint_receive(j6_handle_t handle, size_t *len, void *data)
+endpoint_receive(j6_handle_t handle, j6_tag_t *tag, size_t *len, void *data)
 {
+	if (!tag || !len || (*len && !data))
+		return j6_err_invalid_arg;
+
 	endpoint *e = get_handle<endpoint>(handle);
 	if (!e) return j6_err_invalid_arg;
-	return e->receive(len, data);
+
+	return e->receive(tag, len, data);
 }
 
 j6_status_t
-endpoint_sendrecv(j6_handle_t handle, size_t *len, void *data)
+endpoint_sendrecv(j6_handle_t handle, j6_tag_t *tag, size_t *len, void *data)
 {
+	if (!tag || (*tag & j6_tag_system_flag))
+		return j6_err_invalid_arg;
+
 	endpoint *e = get_handle<endpoint>(handle);
 	if (!e) return j6_err_invalid_arg;
 
-	j6_status_t status = e->send(*len, data);
+	j6_status_t status = e->send(*tag, *len, data);
 	if (status != j6_status_ok)
 		return status;
 
-	return e->receive(len, data);
+	return e->receive(tag, len, data);
+}
+
+j6_status_t
+endpoint_bind_irq(j6_handle_t handle, unsigned irq)
+{
+	endpoint *e = get_handle<endpoint>(handle);
+	if (!e) return j6_err_invalid_arg;
+
+	if (device_manager::get().bind_irq(irq, e))
+		return j6_status_ok;
+
+	return j6_err_invalid_arg;
 }
 
 } // namespace syscalls