KOPT(8-BSD) RISC/os Reference Manual KOPT(8-BSD)
NAME
kopt - examine or modify kernel parameters
SYNTAX
kopt command
DESCRIPTION
kopt is used examine or modify kernel parameters. The ker-
nel parameters that can be altered are defined in the kernel
table kernargs. Only the super-user may change kernel
parameters via kopt, kernel parameters may be examined by
any user.
command may be one of:
get KERNELPARAM Displays the current value KERNELPARAM.
set KERNELPARAM VALUE
Set KERNELPARAM to VALUE. VALUE must be
an integer expressed in any legal C for-
mat.
bis KERNELPARAM VALUE
Or's VALUE into KERNELPARAM.
bic KERNELPARAM VALUE
Clears the bits indicated by 1's in
VALUE in KERNELPARAM.
The kernel parameters may generally be set from the boot
command line, and their defaults may generally be changed
via binary reconfiguration. The currently defined kernel
parameters, which may be usefully accessed via kopt include
the following:
showconfig If non-zero, drivers print configuration
information at startup time. (Read only.)
machine_type Processor type code. (Read only.)
disable_parity Disable parity checking on machines with par-
ity memory. (Read only.)
cache_bufs Cache disk buffers. (Read only.)
memory_limit Maximum amount of memory to use. (Read
only.)
maxmem Maximum amount of memory being used. (Read
only.)
silo If non-zero, use hardware SILO for serial
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ports, if available. (Read only.)
_nfs_sync_writes
If zero, a server will perform NFS writes
synchronously. See fstab (4) for more
details.
_posix_chown_restricted
If zero, fchown and chown(2) may not change
the owner of a file, unless executed by the
super-user, and may not change the group of a
file to a group of which the current user is
not a member, unless executed by the super-
user. The default value is -1 (disabled);
setting this parameter to 0 obtains the 4.3
BSD behavior.
_posix_vdisable
If enabled (set to other than -1), a terminal
control character set to the value of this
parameter never match any input character.
If disabled (set to -1), there is no reserved
value for terminal input control characters
which prevents matching of input characters
with input control characters set to that
value. The default is 0.
_riscos_group_parent
If zero, a newly created file will have the
group of the directory in which it is
created. If non-zero, a newly created file
will have the principal group of the process
which created it. The default is -1 (dis-
abled); setting this parameter to 0 obtains
the 4.3 BSD behavior.
_riscos_kill_stopped_orphans
If zero and the parent of a traced process
exits, the child will be continued and sent a
SIGKILL signal. If non-zero, the child will
be continued. The default is -1 (disabled);
setting this parameter to 0 obtains the 4.3
BSD behavior.
_riscos_link_owner
If zero, only the owner of a file may create
a hard link to it. If non-zero, any user
with write permission for the file may do so.
The default is -1 (disabled).
_riscos_max_disk_quota_cache
The maximum number of disk quota entries to
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be cached by the kernel. One entry is needed
for each logged-in user per file system which
has quotas enabled. Entries are recycled
with an LRU scheme, so a typical maximum
should be employed. Since the quota system
initially starts with zero entries allocated,
no memory will be used if quotas are never
enabled. The default maximum is machine
dependent.
_riscos_utime_owner
If zero, only the owner of a file (or the
super-user) may use the utime system call
with respect to the file. If non-zero, any
user may potentially be able to use utime if
they have write permission on the file. See
utime (2) for more details. The default is
-1 (disabled); setting this parameter to 0
obtains the 4.3 BSD behavior.
_riscos_ttys_default_clocal
If enabled, terminal lines default to CLOCAL
enabled for minor devices numbered 0 through
127, and CLOCAL disabled for minor devices
numbered 128 through 255. If the kopt is dis-
abled, the above CLOCAL defaults are
reversed, to more closely match the behavior
of other UNIX systems. (See termio(7) for a
description of the CLOCAL option.) RISC/os
has adopted the convention that terminal
minor device i, 0<=i<=127, is the same as
terminal minor device i+128, except that the
CLOCAL default is inverted for one, relative
to the other. This allows one (CLOCAL dis-
abled) to be used by default for applications
such as dial-in modems or terminals which
autologout when they are turned off, and the
other (CLOCAL enabled) to be used for local
terminals. The default is 0 (enabled); set
to -1 (disabled) for compatibility with
RISC/os 3.10.
_riscos_svr4_beta_compat
If enabled (default value of 0 is disabled),
-systype svr4 binaries, having a modification
timestamp value less than the value of this
parameter, and not containing a magic number
in the startup code for the binary, which is
present in all RISC/os 5.0 FCS binaries, will
be executed in a binary compatibility mode
which preserves their correct operation. Due
to certain problems in the RISC/os 5.0 Beta
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Test release, certain -systype svr4 binaries
built under that release are incompatible
with the final RISC/os 5.0 release. If a
site has run RISC/os 5.0 Beta, and still has
-systype svr4 binaries built under that
release, it may provide for their continued
use by setting this variable to the current
time, in seconds, as of when RISC/os 5.0 FCS
is installed. No other sites should use this
feature, since it may cause ABI-compliant
binaries from other operating systems, which
are older than the date of installation of
RISC/os 5.0 FCS, to execute incorrectly.
Sites which do use this transitional feature
should recompile all their RISC/os 5.0 Beta-
based -systype svr4 binaries as soon as is
convenient, as this feature will be removed
in the RISC/os 6.0 release. This parameter
may be changed permanently for an operating
system kernel, by binary reconfiguration.
_serial_options
The zero bit (value 1) turns on the "drain
output on close" option. When set this
causes the output to drain immediately upon
close even if the output has been stopped
with XOFF (or tcflow(TCOOFF)). This allows
VSX test "POSIX.os/devclass/i_close.1" to
pass, though waiver PG3san.148 allows output
to not be drained until an explicit XON has
been received (or tcflow(TCOON)).
The one bit (value 2) turns on the "EOF when
not at BOL". 4.52 sent an EOF (0 byte read)
when an EOF (usually ^D) character was input,
whether it was the first character in the
line or not. Thus if you input 10 characters
and then an EOF, the first read would return
10 charaters and a second read would return 0
characters immediately.
The current SVR4 SVID states that inputting
an EOF character shall only cause the current
line to be sent to the reader and if it's
empty, then a 0 byte read is returned. Oth-
erwise the only effect is the read is satis-
fied before the usual NL character. Thus in
the previous example, the first read would
return 10 characters, and the second read
would wait for more characters to be input.
The default for both of these bits is off.
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multicast_select
The zero bit (value 1) enables the
MULTICAST_ALL option. Any multicast packet
received is passed up to the stream (or
socket) whether it was requested or not.
Useful for pre 5.0 programs that don't select
specific addresses.
The one bit (value 2) enables the
MULTICAST_SELECTALL option. This causes any
Add Multicast Address request to actually
fill the hardware filter for all addresses to
be received by the hardware interface.
Should be used for CNP-10 equiped systems.
Also for pre RISC/os 5.0 programs that don't
select specific addresses.
In most cases, the these bits should be set
and cleared together. The default for both
of these bits is off.
FILES
/usr/src/uts/mips/os/debug.c kernel source file containing
kernargs
/usr/src/uts/mips/master.d/kernel.common
kernel source file containing
default values for many of the
kernel parameters.
DIAGNOSTICS
Various messages about unknown parameters, self-explanatory.
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