HP-UX Reference (11i v1 00/12) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man7/!!!intro.7
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t
termio(7) termio(7)
TIOCSWINSZ Set the terminal size values from the winsize structure referenced by arg. If any of
the new values differ from previous values, a SIGWINCH signal is sent to all
processes in the terminal’s foreground process group.
Console Output Redirection IOCTL Command
Output which would normally be sent to the system console may be redirected to any other TTY device or
pseudo-device in the system. The ioctl() system call used to control console output redirection has the
form:
ioctl (fildes, command, arg)
int arg;
The command using this form is:
TIOCCONS Redirect system console output. Any output that would normally be sent to the sys-
tem console, either through kernel printf requests, or through the console special file,
will instead be sent to the terminal referenced by fildes. The value of arg is ignored.
The user must have superuser privileges to execute this request. Otherwise, the call
returns −1 with errno set to EPERM. If the console output has not been redirected
to a different device by a later call to this command, it is redirected back to the physi-
cal console device when fildes is closed.
WARNINGS
Various
HP-UX implementations use non-serial interfaces that look like terminals (such as bit-mapped
graphics displays) or ‘‘smart cards’’ that cannot implement the exact capabilities described above. There-
fore, not all systems can exactly meet the standard stated above. Each implementation is required to state
any deviations from the standard as part of its system-specific documentation.
FIOSSAIOSTAT is similar to BSD 4.2 FIOASYNC, with the addition of provisions for security.
FIOGSAIOSTAT is of HP origin, complements FIOSSAIOSTAT , and allows saving and restoring
system asynchronousI/O TTY states for command interpreter processes.
FIOSSAIOOWN is similar to BSD 4.2 FIOSETOWN, with additional provisions for security.
FIOGSAIOOWN is similar to BSD FIOGETOWN. 4.2 Note also the difference that the BSD 4.2 ver-
sion of this functionality used process groups, while the
HP-UX version only uses
processes.
FIOSNBIO is the same as BSD FIONBIO, 4.2 except that it does not interfere with the
O_NDELAY or O_NONBLOCK open() and fcntl() flags.
FIOGNBIO is of HP origin, complements FIOSNBIO, and allows saving and restoring the
FIOSNBIO-style non-blockingI/O TTY state for command interpreter processes.
The general terminal interface uses a system resource known as a cblock to store data being transmitted
or received through a communications port. These cblocks are continuously used and freed for reuse as
data pass through the system. If too few cblocks are configured in the system, the cblock pool may be tem-
porarily or permanently exhausted, and data loss, system hangs, or reduced system performance can
result.
If cblock exhaustion is suspected, you can examine the system message buffer with
dmesg (see dmesg(1M))
for messages indicating cblock exhaustion has occurred. Or, you can use
adb (see adb(1)) if examining the
corefile of a dump. The message format is
WARNING: cblock exhaustion occurred n times
where n indicates the number of times the operating system has requested a cblock and none could be pro-
vided. If this message is observed, the kernel should be reconfigured to generate a larger number of
cblocks.
A cblock is 32 bytes in length. The default number of cblocks configured in the system is computed from
the tunable system parameter
maxusers, and is defined to be
100+16*maxusers
This can be overridden by using the optional tunable system parameter nclist to specify the desired
number of cblocks to be used in the system.
SAM or config(1M) may be used to generate a new kernel with a new
nclist value.
HP-UX Release 11i: December 2000 − 18 − Section 7−−177
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