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

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dld.sl(5) dld.sl(5)

• Amount of memory used by the hash table

DIAGNOSTICS

If the dynamic loader is not present, or cannot be invoked by the process for any reason, an error message

is printed to standard error and the process terminates with a non-zero exit code.

These errors fall into two basic categories: errors in attaching a shared library, and errors in binding sym-

bols. The former can occur only at process startup time but the latter can occur at any time during process

execution unless the -B immediate option is used with ld. Possible errors that can occur while attach-

ing a shared library include library not present, library not executable, library corrupt, high water mark too

low, or insufﬁcient room in the address space for the library. Possible errors that can occur while binding

symbols include symbol not found (unresolved external), or library corrupt.

When using the explicit load facilities of the dynamic loader, these types of errors are not considered fatal.

Consult shl_load(3X), dlclose(3C), dlget(3C), dlgetname(3C), dlmodinfo(3C), dlopen(3C), and dlsym(3C) for

more information. On PA64, to see error messages, use the dlerror() routine. This routine will print

the last error message recorded by the dynamic loader.

WARNINGS

The startup cost of the dynamic loader is signiﬁcant, even with deferred binding, and can cause severe per-

formance degradation in processes dominated by startup costs (such as simple ‘‘hello world’’ programs). In

addition, position-independent code is usually slower than normal code, so performance of a program may

be adversely affected by the presence of PIC in shared libraries. However, the advantages of decreased disk

space usage and decreased memory requirements for executables should outweigh these concerns in most

cases.

There are rare cases where the behavior of a program differs when using shared libraries as opposed to

archive libraries. This happens primarily when relying on undocumented and unsupported features of the

compilers, assembler, and linker. See the +help option to ld(1) or the HP-UX Linker and Libraries User’s

Guide manual for more details.

The library developer is entirely responsible for version control and must be thorough in identifying incom-

patible changes to library interfaces. Otherwise, programs may malfunction unexpectedly with later ver-

sions of the library. There is little an application user can do if version control is not handled properly by

the library developer. The application developer can usually resolve problems by modifying the source code

to use the new interfaces then recompiling and relinking against the new libraries.

By default, most warnings are not reported by the dynamic loader.

On PA32, if you wish to see all of the messages, set the environment variable

_HP_DLDOPTS to contain

one or more options. The following options are supported:

-warnings Display additionaldynamic loader warning messages. Some of these include:

• Symbols of the same name but different types, such as CODE and DATA. See the

WARNINGS section in ld(1) for more details on this warning.

• Using certain ﬂags or routines described in shl_load(3X).

-fbverbose See fastbind(1).

-nofastbind See fastbind(1).

On PA64, if you wish to see all error messages, set the environment variable

DLD_VERBOSE_ERR to true.

AUTHOR

The

/usr/lib/dld.sl and

/usr/lib/pa20_64/dld.sl shared libraries were developed by HP.