Here are the changes to create 256 ADDITIONAL TTY/PTY pairs in addition to the 64 in current 1.2.0 (and previous) kernels. (The NPTY -package does not use so much memory, as like all TTYs, the necessary buffers are allocated only when the PTY-pair is opened..) mknod /dev/ttyt0 c 3 0 (TTY256 major: 3) mknod /dev/ptyt0 c 2 0 (PTY256 major: 2) (etc.) Your PROBLEM will be to choose proper PTY sequence letters, and have your applications to support them... /Matti Aarnio 10-Apr-95 diff -u -r --new-file linux-1200virgin/drivers/char/Makefile linux-1200/drivers/char/Makefile --- linux-1200virgin/drivers/char/Makefile Wed Feb 15 10:50:55 1995 +++ linux-1200/drivers/char/Makefile Mon Mar 13 12:32:08 1995 @@ -17,11 +17,11 @@ $(CC) $(CFLAGS) -c $< OBJS = tty_io.o n_tty.o console.o keyboard.o serial.o \ - tty_ioctl.o pty.o vt.o mem.o vc_screen.o \ + tty_ioctl.o pty.o npty.o vt.o mem.o vc_screen.o \ defkeymap.o consolemap.o vesa_blank.o selection.o SRCS = tty_io.c n_tty.c console.c keyboard.c serial.c \ - tty_ioctl.c pty.c vt.c mem.c vc_screen.c \ + tty_ioctl.c pty.c npty.c vt.c mem.c vc_screen.c \ defkeymap.c consolemap.c vesa_blank.c selection.c diff -u -r --new-file linux-1200virgin/drivers/char/npty.c linux-1200/drivers/char/npty.c --- linux-1200virgin/drivers/char/npty.c Thu Jan 1 02:00:00 1970 +++ linux-1200/drivers/char/npty.c Mon Mar 13 14:22:45 1995 @@ -0,0 +1,267 @@ +/* + * linux/drivers/char/npty.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * NPTY trickery by Matti Aarnio who wants to have 256 ptys! + */ + +/* + * npty.c + * + * This module exports the following pty function: + * + * int npty_open(struct tty_struct * tty, struct file * filp); + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +struct pty_struct { + int magic; + struct wait_queue * open_wait; +}; + +#define PTY_MAGIC 0x5001 + +#define PTY_BUF_SIZE PAGE_SIZE/2 + +/* + * tmp_buf is used as a temporary buffer by pty_write. We need to + * lock it in case the memcpy_fromfs blocks while swapping in a page, + * and some other program tries to do a pty write at the same time. + * Since the lock will only come under contention when the system is + * swapping and available memory is low, it makes sense to share one + * buffer across all the PTY's, since it significantly saves memory if + * large numbers of PTY's are open. + */ +static unsigned char *tmp_buf; +static struct semaphore tmp_buf_sem = MUTEX; + +struct tty_driver npty_driver, npty_slave_driver; +static int pty_refcount = 0; + +static struct tty_struct *pty_table[NR_NPTYS]; +static struct termios *pty_termios[NR_NPTYS]; +static struct termios *pty_termios_locked[NR_NPTYS]; +static struct tty_struct *ttyp_table[NR_NPTYS]; +static struct termios *ttyp_termios[NR_NPTYS]; +static struct termios *ttyp_termios_locked[NR_NPTYS]; +static struct pty_struct npty_state[NR_NPTYS]; + +#define MIN(a,b) ((a) < (b) ? (a) : (b)) + +static void pty_close(struct tty_struct * tty, struct file * filp) +{ + if (!tty) + return; + if (tty->driver.subtype == PTY_TYPE_MASTER) { + if (tty->count > 1) + printk("master pty_close: count = %d!!\n", tty->count); + } else { + if (tty->count > 2) + return; + } + wake_up_interruptible(&tty->read_wait); + wake_up_interruptible(&tty->write_wait); + if (!tty->link) + return; + wake_up_interruptible(&tty->link->read_wait); + wake_up_interruptible(&tty->link->write_wait); + if (tty->driver.subtype == PTY_TYPE_MASTER) + tty_hangup(tty->link); + else { + start_tty(tty); + set_bit(TTY_SLAVE_CLOSED, &tty->link->flags); + } +} + +/* + * The unthrottle routine is called by the line discipline to signal + * that it can receive more characters. For PTY's, the TTY_THROTTLED + * flag is always set, to force the line discipline to always call the + * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE + * characters in the queue. This is necessary since each time this + * happens, we need to wake up any sleeping processes that could be + * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() + * for the pty buffer to be drained. + */ +static void pty_unthrottle(struct tty_struct * tty) +{ + struct tty_struct *o_tty = tty->link; + + if (!o_tty) + return; + + if ((o_tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && + o_tty->ldisc.write_wakeup) + (o_tty->ldisc.write_wakeup)(o_tty); + wake_up_interruptible(&o_tty->write_wait); + set_bit(TTY_THROTTLED, &tty->flags); +} + +static int pty_write(struct tty_struct * tty, int from_user, + unsigned char *buf, int count) +{ + struct tty_struct *to = tty->link; + int c=0, n, r; + char *temp_buffer; + + if (!to || tty->stopped) + return 0; + + if (from_user) { + down(&tmp_buf_sem); + temp_buffer = tmp_buf + + ((tty->driver.subtype-1) * PTY_BUF_SIZE); + while (count > 0) { + n = MIN(count, PTY_BUF_SIZE); + memcpy_fromfs(temp_buffer, buf, n); + r = to->ldisc.receive_room(to); + if (r <= 0) + break; + n = MIN(n, r); + to->ldisc.receive_buf(to, temp_buffer, 0, n); + buf += n; c+= n; + count -= n; + } + up(&tmp_buf_sem); + } else { + c = MIN(count, to->ldisc.receive_room(to)); + to->ldisc.receive_buf(to, buf, 0, c); + } + + return c; +} + +static int pty_write_room(struct tty_struct *tty) +{ + struct tty_struct *to = tty->link; + + if (!to || tty->stopped) + return 0; + + return to->ldisc.receive_room(to); +} + +static int pty_chars_in_buffer(struct tty_struct *tty) +{ + struct tty_struct *to = tty->link; + + if (!to || !to->ldisc.chars_in_buffer) + return 0; + + return to->ldisc.chars_in_buffer(to); +} + +static void pty_flush_buffer(struct tty_struct *tty) +{ + struct tty_struct *to = tty->link; + + if (!to) + return; + + if (to->ldisc.flush_buffer) + to->ldisc.flush_buffer(to); + + if (to->packet) { + tty->ctrl_status |= TIOCPKT_FLUSHWRITE; + wake_up_interruptible(&to->read_wait); + } +} + +int npty_open(struct tty_struct *tty, struct file * filp) +{ + int line; + struct pty_struct *pty; + + if (!tty || !tty->link) + return -ENODEV; + line = MINOR(tty->device) - tty->driver.minor_start; + if ((line < 0) || (line >= NR_NPTYS)) + return -ENODEV; + pty = npty_state + line; + tty->driver_data = pty; + + if (!tmp_buf) { + tmp_buf = (unsigned char *) get_free_page(GFP_KERNEL); + if (!tmp_buf) + return -ENOMEM; + } + + if (tty->driver.subtype == PTY_TYPE_SLAVE) + clear_bit(TTY_SLAVE_CLOSED, &tty->link->flags); + wake_up_interruptible(&pty->open_wait); + set_bit(TTY_THROTTLED, &tty->flags); + if (filp->f_flags & O_NDELAY) + return 0; + while (!tty->link->count && !(current->signal & ~current->blocked)) + interruptible_sleep_on(&pty->open_wait); + if (!tty->link->count) + return -ERESTARTSYS; + return 0; +} + +long npty_init(long kmem_start) +{ + memset(&npty_state, 0, sizeof(npty_state)); + memset(&npty_driver, 0, sizeof(struct tty_driver)); + npty_driver.magic = TTY_DRIVER_MAGIC; + npty_driver.name = "pty256"; + npty_driver.major = NTTY_MAJOR; + npty_driver.minor_start = 0; + npty_driver.num = NR_NPTYS; + npty_driver.type = TTY_DRIVER_TYPE_PTY; + npty_driver.subtype = PTY_TYPE_MASTER; + npty_driver.init_termios = tty_std_termios; + npty_driver.init_termios.c_iflag = 0; + npty_driver.init_termios.c_oflag = 0; + npty_driver.init_termios.c_cflag = B38400 | CS8 | CREAD; + npty_driver.init_termios.c_lflag = 0; + npty_driver.flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW; + npty_driver.refcount = &pty_refcount; + npty_driver.table = pty_table; + npty_driver.termios = pty_termios; + npty_driver.termios_locked = pty_termios_locked; + npty_driver.other = &npty_slave_driver; + + npty_driver.open = npty_open; + npty_driver.close = pty_close; + npty_driver.write = pty_write; + npty_driver.write_room = pty_write_room; + npty_driver.flush_buffer = pty_flush_buffer; + npty_driver.chars_in_buffer = pty_chars_in_buffer; + npty_driver.unthrottle = pty_unthrottle; + + npty_slave_driver = npty_driver; + npty_slave_driver.name = "tty256"; + npty_slave_driver.major = NPTY_MAJOR; + npty_slave_driver.subtype = PTY_TYPE_SLAVE; + npty_slave_driver.minor_start = 0; + npty_slave_driver.init_termios = tty_std_termios; + npty_slave_driver.init_termios.c_cflag = B38400 | CS8 | CREAD; + npty_slave_driver.table = ttyp_table; + npty_slave_driver.termios = ttyp_termios; + npty_slave_driver.termios_locked = ttyp_termios_locked; + npty_slave_driver.other = &npty_driver; + + tmp_buf = 0; + + if (tty_register_driver(&npty_driver)) + panic("Couldn't register pty driver"); + if (tty_register_driver(&npty_slave_driver)) + panic("Couldn't register pty slave driver"); + + return kmem_start; +} diff -u -r --new-file linux-1200virgin/drivers/char/tty_io.c linux-1200/drivers/char/tty_io.c --- linux-1200virgin/drivers/char/tty_io.c Mon Feb 20 21:29:52 1995 +++ linux-1200/drivers/char/tty_io.c Mon Mar 13 14:21:42 1995 @@ -1739,6 +1739,7 @@ kmem_start = cy_init(kmem_start); #endif kmem_start = pty_init(kmem_start); + kmem_start = npty_init(kmem_start); kmem_start = vcs_init(kmem_start); return kmem_start; } diff -u -r --new-file linux-1200virgin/include/linux/major.h linux-1200/include/linux/major.h --- linux-1200virgin/include/linux/major.h Thu Feb 23 13:31:40 1995 +++ linux-1200/include/linux/major.h Mon Mar 13 12:52:13 1995 @@ -19,8 +19,8 @@ * -------------------- -------------------- -------------------- * 0 - unnamed unnamed minor 0 = true nodev * 1 - /dev/mem ramdisk - * 2 - floppy - * 3 - hd + * 2 - /dev/tty??(256) floppy + * 3 - /dev/pty??(256) hd * 4 - /dev/tty* * 5 - /dev/tty; /dev/cua* * 6 - lp @@ -50,9 +50,11 @@ */ #define UNNAMED_MAJOR 0 -#define MEM_MAJOR 1 -#define FLOPPY_MAJOR 2 -#define IDE0_MAJOR 3 +#define MEM_MAJOR 1 /* char */ +#define NTTY_MAJOR 2 /* char */ +#define FLOPPY_MAJOR 2 /* block */ +#define NPTY_MAJOR 3 /* char */ +#define IDE0_MAJOR 3 /* block */ #define HD_MAJOR IDE0_MAJOR #define TTY_MAJOR 4 #define TTYAUX_MAJOR 5 diff -u -r --new-file linux-1200virgin/include/linux/tty.h linux-1200/include/linux/tty.h --- linux-1200virgin/include/linux/tty.h Sun Feb 26 16:45:26 1995 +++ linux-1200/include/linux/tty.h Mon Mar 13 14:05:59 1995 @@ -27,6 +27,7 @@ /* Note: the ioctl VT_GETSTATE does not work for consoles 16 and higher (since it returns a short) */ #define NR_PTYS 64 +#define NR_NPTYS 256 /* Another scheme for PTYs! */ #define NR_LDISCS 16 /* @@ -278,6 +279,7 @@ extern long lp_init(long); extern long con_init(long); extern long pty_init(long); +extern long npty_init(long); extern long tty_init(long); extern long vcs_init(long); #ifdef CONFIG_CYCLADES