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HP Services Software Patches - axplibo02_061_libots
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Copyright (c) Digital Equipment Corporation 1994, 1995. All rights reserved.
OP/SYS: OpenVMS Alpha
COMPONENTS: LIBOTS
SOURCE: Digital Equipment Corporation
ECO INFORMATION:
ECO Kit Name: AXPLIBO02_061
ECO Kits Superseded by This ECO Kit: AXPLIBO01_061
ECO Kit Approximate Size: 670 Blocks
Kit Applies To: OpenVMS Alpha V6.1, V6.1-1H1, V6.1-1H2
System Reboot Necessary: Yes
ECO KIT SUMMARY:
An ECO kit exists for LIBOTS on OpenVMS Alpha V6.1 through V6.1-1H2.
This kit addresses the following problems:
Problems addressed in the AXPLIBO02_061 kit:
o Using the compiler switch /GRANULARITY=BYTE will cause the wrong
bits to be fetched. This could result in user programs that
cause data corruption.
o Small X-Floats in T-Float denorm range were being incorrectly
converted to zero.
o T-Float denorms converted to X-Float were incorrect by a factor
of 2.
NOTE: The X-Float datatype is a new datatype supported by
OpenVMS Alpha starting with OpenVMS Alpha V6.1. It is a
128 bit IEEE floating point datatype that is implemented
in software, specifically LIBOTS. X-Float is represented
as a REAL*16 in Fortran.
Problems addressed in the AXPLIBO01_061 kit:
o The LIBOTS routine OTS$INSV_VOL can write values to the wrong
address and corrupt data.
The LIBOTS INSV/EXTV corruption can be seen if a volatile
longword doesn't start on a byte-boundary. This can seen
in languages like C and Pascal when dealing with poorly aligned
data.
For Pascal, you can see it with a record like:
type r = packed record
f1 : boolean;
f2 : integer;
end;
For C, you can see it with a record like:
#pragma nomember_alignment
struct r {
unsigned f1 : 1;
unsigned f2 : 32;
};
Given a Pascal user's tendency to use the PACKED keyword, the
problem is more likely to occur in Pascal rather than C. C users
would have to go out of their way to use a 32-bit bitfield which
is not very common. This problem can also be seen from BLISS and
possibly Ada.
INSTALLATION NOTES:
In order for the corrections in this kit to take effect, the system
must be rebooted. If the system is a member of a VMScluster, the entire
cluster should be rebooted in order to make use of the new image(s).
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Files on this server are as follows:
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»axplibo02_061_libots.README
»axplibo02_061.CHKSUM
»axplibo02_061.a-dcx_axpexe
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