2008-02-04 10:21:12 /dev/ptmx - wrong
Duane Ellis (UNITED STATES)
Message: 50631
The "/dev/ptmx" feature is (pseudo terminals) has a problem.
In the end, the function ptsname() returns a device name that does not exist.
For example if the PTY is 7, it should return /dev/pts/7 -which it does
The device /dev/pts/7 (with the slash) does not exist.
The device /dev/pts7 {without the slash} does exist.
The work around is: muck with the filename returned by ptsname()
Works just fine on x86-linux, but wrong on blackfin-uclinux.
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
int
main( int argc, char **argv )
{
char *cp;
int h;
h = open( "/dev/ptmx", O_RDWR | O_NOCTTY | O_NONBLOCK );
if( h < 0 ){
printf("Cannot open PTMX, error: %d %s\n", errno, strerror(errno));
exit(1);
}
cp = ptsname(h);
printf("PTMX Name is: %s\n", cp);
for(;;)
;
}
-Duane.
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2008-02-04 12:15:01 Re: /dev/ptmx - wrong
Robin Getz (UNITED STATES)
Message: 50636 Duane:
On the target:
root:~> cat /proc/filesystems | grep pts
nodev devpts
root:~> mount | grep pts
devpts on /dev/pts type devpts (rw)
When I have telnet into the board (activate a pseudo terminal)
root:~> ls -l /dev/pts/*
crw------- 1 root root 136, 0 Aug 6 11:53 /dev/pts/0
root:~> find /dev/ -name "pt*"
/dev/ptmx
/dev/pts
When I run your application (on the target)
root:~> /var/a.out
PTMX Name is: /dev/pts/1
Can you double check that devpts is mounted properly?
-Robin
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2008-02-04 13:30:37 Re: /dev/ptmx - wrong
Duane Ellis (UNITED STATES)
Message: 50643
>> root:~> mount | grep pts
>> devpts on /dev/pts type devpts (rw)
That seems to make a difference. I did not have it mounted.
I'll have to test my other combinations to see if it is completely fixed.
-Duane.
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2008-02-04 23:40:16 Re: /dev/ptmx - wrong
Mike Frysinger (UNITED STATES)
Message: 50665 if you want to use Unix98 PTY's, you need to have devpts mounted on /dev/pts/ as the kernel will automatically manage it with device nodes as the masters/slaves are created/destroyed
