Sun Bug Reports article 1264381
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 Bug Id:     1264381
 Category:  kernel
 Subcategory:  driver
 State:  closed
 Release summary: 2.5
 Synopsis:  zs driver behaves strangly when setting 115200 baud with stty.
        Integrated in releases:
 Patch id:
 Description:
If you try and set a  baud rate that the hardware does not support, not only
does the ioctl() succeed
which it should not, but the results are unexpected:

EG:

cat </dev/ttya &
This is what you would expect to happen:

mutiny# stty 57600 </dev/ttya
mutiny# stty -a </dev/ttya
speed 57600 baud;
rows = 0; columns = 0; ypixels = 0; xpixels = 0;
eucw 1:0:0:0, scrw 1:0:0:0
intr = ^c; quit = ^|; erase = ^?; kill = ^u;
eof = ^d; eol = <undef>; eol2 = <undef>; swtch =
<undef>;
start = ^q; stop = ^s; susp = ^z; dsusp = ^y;
rprnt = ^r; flush = ^o; werase = ^w; lnext = ^v;
-parenb -parodd cs8 -cstopb -hupcl cread -clocal -loblk -crtscts -crtsxoff
-parext
-ignbrk brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl -iuclc
ixon -ixany -ixoff imaxbel
isig icanon -xcase echo echoe echok -echonl -noflsh
-tostop echoctl -echoprt echoke -defecho -flusho -pendin iexten
opost -olcuc onlcr -ocrnl -onocr -onlret -ofill -ofdel tab3

Same for 76800, and all the slower speeds.

Now try 115200:

mutiny# stty 115200 </dev/ttya
mutiny# stty -a </dev/ttya
ispeed 57600 baud; ospeed 115200 baud;     <------ The driver actually sets
speed to 57600
rows = 0; columns = 0; ypixels = 0; xpixels = 0;
eucw 1:0:0:0, scrw 1:0:0:0
intr = ^c; quit = ^|; erase = ^?; kill = ^u;
eof = ^d; eol = <undef>; eol2 = <undef>; swtch =
<undef>;
start = ^q; stop = ^s; susp = ^z; dsusp = ^y;
rprnt = ^r; flush = ^o; werase = ^w; lnext = ^v;
-parenb -parodd cs8 -cstopb -hupcl cread -clocal -loblk -crtscts -crtsxoff
-parext
-ignbrk brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl -iuclc
ixon -ixany -ixoff imaxbel
isig icanon -xcase echo echoe echok -echonl -noflsh
-tostop echoctl -echoprt echoke -defecho -flusho -pendin iexten
opost -olcuc onlcr -ocrnl -onocr -onlret -ofill -ofdel tab3

The following program shows that cfgetispeed() and  cfgetospeed() return to
same values as stty.

#include <stdio.h>
#include <errno.h>
#include <termio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ttydev.h>
#include <sys/fcntl.h>
#definePORT "/dev/ttya"

main(argc,argv)

int argc;
char *argv[];
{

        int debug,fd;
        struct termios line;
        char system_string[200];

        debug = 1;

       if((fd = open( PORT , O_RDWR  ,0  )) == -1) {
                 perror( "Error Opening Serial Device ");
                 exit(1);

        }

        if(tcgetattr(fd, &line) == -1) {
                perror("Error getting characteristics");
        }

        if(debug) {
                printf("\n\nPort settings are:\n\n");
                sprintf(system_string, "/usr/bin/stty -a < %s" , PORT);
                printf("Exit status %d\n" , system(system_string));
        }

        printf("IBAUD = %d\n" , cfgetispeed( &line));
        printf("OBAUD = %d\n" , cfgetospeed( &line));

        close(fd);
        exit(0);
}

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