I just got one response for the following message:
>>The man page for 'uac' speaks of Unaligned Access Control, but it does not
>>mention how to use all its options.
>>
>>Doing a 'uac p' gives:
>>
>>parent printing is on
>> fixup is on
>> sigbus is off
>>
>>Doing a 'uac error' gives:
>>
>>usage: uac [sp] [01]
>> uac p [noprint nofix sigbus reset]
>> uac s [noprint reset]
>>
>>I came across a article in Net News about turning the sigbus option on so a
>>signal segmentation fault accurs when a 'uac' error occurs, so that it core
>>dumps and you can debug the code.
>>
>>Does anybody have any notes on how to use all the options with this the
>>'uac' command as it is clearly not specified in the man pages or any doc
>>books.
Benoit Maillard gave a listing of a man page for the command which explains
what I want to know:
--------------------------------------------------------------------------------
uac(1) uac(1)
NAME
uac - Unaligned Access Message Control
SYNOPSIS
uac p | s [value]
uac p | s [keyword]
FLAGS
The following flags are used with the uac command:
p Sets or displays the current flag setting for the parent process
s Sets or displays the current flag setting for the system
The following keywords are used with the p flag:
reset
Reset the current flag settings to the default for the parent process
noprint
Do not print the unaligned access warning message for the parent pro-
cess
nofix
Do not fix the unaligned access for the parent process
sigbus
Deliver a SIGBUS signal to the parent process
The following keywords are used with the s flag:
reset
Reset the current flag settings to the default for the system
noprint
Do not print the unaligned access warning message for the system
DESCRIPTION
Most complete instruction set computers (CISC) can access unaligned data
but only at a significantly reduced speed. Most reduced instruction set
computers (RISC) do not attempt to handle unaligned accesses. Instead,
they generate an unaligned access trap and let the operating system handle
the fault.
The default action for the operating system when an unaligned access fault
occurs is to fix the unaligned access fault and then display a warning mes-
sage informing the user process that an unaligned access fault has
occurred. This warning gives you an opportunity to correct the code so
that future unaligned access faults are prevented.
In addition, the default action for the operating system is to not deliver
a SIGBUS signal to the parent process when an unaligned access fault
occurs.
These defaults are satisfactory for most users, but some users require a
different behavior and want to specify their own Unaligned Access Control
(UAC).
The uac command enables or disables the "Fixed up unaligned data access for
pid nnn at pc 0xAddr" messages that are displayed. The command sets or
displays the UAC_NOPRINT, UAC_NOFIX, and UAC_SIGBUS flags, as defined in
setsysinfo(2).
Usually, the parent process is the shell.
If value is not specified, the current flag setting is displayed. You can
specify value as either 0 (zero) or 1 (one). If value is 0 (zero), the
flag is turned on and messages are not displayed. If value is 1 (one), the
flag is turned off and messages are displayed.
Kewords can be used singly, or in any combination. However, the reset key-
word overrides any other keywords it is used with.
RESTRICTIONS
You must be superuser to set the system flag.
EXAMPLES
Both of the following commands disable messages for the parent process:
# uac p 0
# uac p noprint
Both of the following commands enable messages for the system:
# uac s 1
# uac s reset
The following command dispables fixing of an unaligned access fault, dis-
ables printing a message for an unaligned access fault to the parent pro-
cess, and enables delivery of a SIGBUS signal to the parent process:
# uac p nofix noprint sigbus
RELATED INFORMATION
getsysinfo(2), setsysinfo(2)
--------------------------------------------------------------------------------
The man page I get on a Digital Unix 3.0 system is:
--------------------------------------------------------------------------------
uac(1) uac(1)
NAME
uac - Unaligned Access Message Control
SYNOPSIS
uac s | p [value]
FLAGS
The following flags are used with the uac command:
s Sets or displays the current flag setting for the system.
p Sets or displays the current flag setting for the parent process.
DESCRIPTION
Most complete instruction set computers (CISC) can access unaligned data
but only at a significantly reduced speed. Most reduced instruction set
computers (RISC) do not attempt to handle unaligned accesses, but, instead,
generate an "Unaligned Access Trap" and let the operating system handle the
fault.
The default action for unaligned access traps for the operating system is
for the operating system to fix the unaligned access and then display a
warning to the user that an unaligned access has occurred. This provides
an opportunity to correct the code so that unaligned access is prevented.
These defaults are satisfactory for most users, but some users require a
different behavior and want to specify their own Unaligned Access Control
(hence called "UAC").
The uac command enables or disables the "Fixed up unaligned data access for
pid nnn at pc 0xAddr" messages that are displayed. The command sets or
displays the UAC_NOPRINT flag, which determines if the messages for the
system or the parent process of the user are displayed. Usually, the
parent process is the shell.
If value is not specified, the current flag setting is displayed. You can
specify value as either 0 (zero) or 1 (one). If value is 0 (zero), the
flag is turned on and messages are not displayed. If value is 1 (one), the
flag is turned off and messages are displayed.
RESTRICTIONS
You must be superuser to set the system flag.
EXAMPLES
The following command disables messages for the parent process:
# uac p 0
The following command enables messages for the system:
# uac s 1
RELATED INFORMATION
getsysinfo(2), setsysinfo(2)
--------------------------------------------------------------------------------
Which does not explain much at all, obviously my man page is not the up to date
one.
Thanks again
Joe Spanicek
Received on Mon Jul 01 1996 - 01:22:10 NZST