CORRECT MINOR NUMBER FOR COM PORT (SELECT FAILS)

I had the problem with select() not working on com ports. I got no
response from a post regarding this one, so I started to look into it
myself. I found out that the com driver calculates unit = minor(dev) -1;
This has the following implications:
        /dev/com1 corresponds to COM0, /dev/com2 to COM1 (very confusing
                in kernel messages)
        It is incompatible with the config file entries com1 at..., com2 at...
        Unpredictible results will occur if someone puts a com0 at.. in
                his config file.
        It is incompatible with the DOS usage of COM1, COM2 (But who cares 8-)
        ttselect() calculates unit = minor(dev), and uses this as an index in
                com_tty. Because this index is different from that used
                in the com driver, select() on /dev/com1 looks at
                /dev/com2 and select() on /dev/com2 looks at an undefined
                entry in com_tty and returns always true.

WARNING: RE-mknod /dev/com1, /dev/com2, and modify your kernel config!

AUTHOR:		Christoph Robitschko (chmr@fstgds01.tu-graz.ac.at)
386BSD-Patchkit: patch00018

diff --git a/usr/src/sys.386bsd/i386/isa/com.c b/usr/src/sys.386bsd/i386/isa/com.c
index 7047b07..5b1c5fd 100644 (file)
--- a/usr/src/sys.386bsd/i386/isa/com.c
+++ b/usr/src/sys.386bsd/i386/isa/com.c
@@ -31,6 +31,13 @@
  * SUCH DAMAGE.
  *
  *     @(#)com.c       7.5 (Berkeley) 5/16/91
  * SUCH DAMAGE.
  *
  *     @(#)com.c       7.5 (Berkeley) 5/16/91

+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         1       00018
+ * --------------------         -----   ----------------------
+ *
+ * 09 Aug 92   Christoph Robitschko    Correct minor number on com ports

  */
 static char rcsid[] = "$Header: /usr/bill/working/sys/i386/isa/RCS/com.c,v 1.2 92/01/21 14:34:11 william Exp $";
 
  */
 static char rcsid[] = "$Header: /usr/bill/working/sys/i386/isa/RCS/com.c,v 1.2 92/01/21 14:34:11 william Exp $";
 


@@ -108,7 +115,7 @@ extern int kgdb_rate;
 extern int kgdb_debug_init;
 #endif
 
 extern int kgdb_debug_init;
 #endif
 

-#define        UNIT(x)         (minor(x)-1)
+#define        UNIT(x)         (minor(x))

 
 comprobe(dev)
 struct isa_device *dev;
 
 comprobe(dev)
 struct isa_device *dev;


@@ -131,7 +138,7 @@ struct isa_device *isdp;
        u_char          unit;
        int             port = isdp->id_iobase;
 
        u_char          unit;
        int             port = isdp->id_iobase;
 

-       unit = isdp->id_unit - 1;
+       unit = isdp->id_unit;

        if (unit == comconsole)
                DELAY(1000);
        com_addr[unit] = port;
        if (unit == comconsole)
                DELAY(1000);
        com_addr[unit] = port;


@@ -149,7 +156,7 @@ struct isa_device *isdp;
        outb(port+com_ier, 0);
        outb(port+com_mcr, 0 | MCR_IENABLE);
 #ifdef KGDB
        outb(port+com_ier, 0);
        outb(port+com_mcr, 0 | MCR_IENABLE);
 #ifdef KGDB

-       if (kgdb_dev == makedev(commajor, unit+1)) {
+       if (kgdb_dev == makedev(commajor, unit)) {

                if (comconsole == unit)
                        kgdb_dev = -1;  /* can't debug over console port */
                else {
                if (comconsole == unit)
                        kgdb_dev = -1;  /* can't debug over console port */
                else {


@@ -239,7 +246,7 @@ comclose(dev, flag, mode, p)
        outb(com+com_cfcr, inb(com+com_cfcr) & ~CFCR_SBREAK);
 #ifdef KGDB
        /* do not disable interrupts if debugging */
        outb(com+com_cfcr, inb(com+com_cfcr) & ~CFCR_SBREAK);
 #ifdef KGDB
        /* do not disable interrupts if debugging */

-       if (kgdb_dev != makedev(commajor, unit+1))
+       if (kgdb_dev != makedev(commajor, unit))

 #endif
        outb(com+com_ier, 0);
        if (tp->t_cflag&HUPCL || tp->t_state&TS_WOPEN || 
 #endif
        outb(com+com_ier, 0);
        if (tp->t_cflag&HUPCL || tp->t_state&TS_WOPEN || 


@@ -283,7 +290,7 @@ comintr(unit)
        register u_char code;
        register struct tty *tp;
 
        register u_char code;
        register struct tty *tp;
 

-       unit--;
+       unit;

        com = com_addr[unit];
        while (1) {
                code = inb(com+com_iir);
        com = com_addr[unit];
        while (1) {
                code = inb(com+com_iir);


@@ -300,7 +307,7 @@ comintr(unit)
 #define        RCVBYTE() \
                        code = inb(com+com_data); \
                        if ((tp->t_state & TS_ISOPEN) == 0) { \
 #define        RCVBYTE() \
                        code = inb(com+com_data); \
                        if ((tp->t_state & TS_ISOPEN) == 0) { \

-                               if (kgdb_dev == makedev(commajor, unit+1) && \
+                               if (kgdb_dev == makedev(commajor, unit) && \

                                    code == FRAME_END) \
                                        kgdb_connect(0); /* trap into kgdb */ \
                        } else \
                                    code == FRAME_END) \
                                        kgdb_connect(0); /* trap into kgdb */ \
                        } else \


@@ -359,7 +366,7 @@ comeint(unit, stat, com)
 #ifdef KGDB
                /* we don't care about parity errors */
                if (((stat & (LSR_BI|LSR_FE|LSR_PE)) == LSR_PE) &&
 #ifdef KGDB
                /* we don't care about parity errors */
                if (((stat & (LSR_BI|LSR_FE|LSR_PE)) == LSR_PE) &&

-                   kgdb_dev == makedev(commajor, unit+1) && c == FRAME_END)
+                   kgdb_dev == makedev(commajor, unit) && c == FRAME_END)

                        kgdb_connect(0); /* trap into kgdb */
 #endif
                return;
                        kgdb_connect(0); /* trap into kgdb */
 #endif
                return;


@@ -616,7 +623,7 @@ comcnprobe(cp)
        /* make sure hardware exists?  XXX */
 
        /* initialize required fields */
        /* make sure hardware exists?  XXX */
 
        /* initialize required fields */

-       cp->cn_dev = makedev(commajor, unit+1);
+       cp->cn_dev = makedev(commajor, unit);

        cp->cn_tp = &com_tty[unit];
 #ifdef COMCONSOLE
        cp->cn_pri = CN_REMOTE;         /* Force a serial port console */
        cp->cn_tp = &com_tty[unit];
 #ifdef COMCONSOLE
        cp->cn_pri = CN_REMOTE;         /* Force a serial port console */