Binary Compatibility Guide

Warnings and Side Effects

File Descriptor Limit

The default limit on the number of file descriptors that a process can open is 64. The limit can be increased through the limit command of csh(1), the ulimit command of sh(1) and ksh(1), and the setrlimit(2) system call. If the limit on the number of file descriptors is increased to more than 256 a process running under either static or dynamic BCP can fail. The failure can happen even though fewer than 256 files are open. Most 4.x applications can handle only 256 file descriptors.

Device Numbers

In SunOS 4.x, the largest major device number that the system supported was 255. SunOS 5.x has a much larger limit on the major device number. A 4.x application running under either static or dynamic BCP will not be able to recognize a device number greater than 255, even though the device number is legitimate.

Dynamic Linking Default

To enable dynamic linking of executables that are partially statically linked, the package defaults to always allowing dynamic linking. This causes a modest loss of performance for completely statically linked SunOS 4.x executables. This feature can be disabled by changing to superuser mode and adding the following line to the "set:" section of the /etc/system file:

set enable_mixed_bcp=0