Solaris 1.x to 2.x Transition Guide

Chapter 15 Compilers, Linkers, and Debuggers

This chapter discusses the changes to compilers, linkers, and debuggers.

Compilers

The single most significant change for developers migrating from the SunOS release 4.x to the Solaris 2.6 operating environment is the unbundling of the C compiler. One of the factors that allowed the compiler to be unbundled is the dynamic kernel. The compiler is no longer required to reconfigure the kernel as devices are now automatically loaded by the kernel as needed.

An ANSI C compiler is available with unbundled Sun WorkShop(TM). This compiler produces executables in executable and linking format (ELF), the native object format of Solaris 2.6 executables. lint and the lint libraries are also unbundled.

Source Compatibility Guide describes the differences between the C language as implemented by the SunOS release 4.x C compiler (Sun C) and as described by the ANSI Programming Language C document (ANSI C). These differences should be addressed when porting source written for the Sun C compiler to an ANSI C conforming compiler.

Compiler Option Differences

Table 15-1 compares the SunOS release 4.x Sun C and ANSI C compilers to the Solaris 2.6 Sun WorkShop(TM) C++ 4.2. It is provided for your information, and is not intended to describe the range of operations available in default Solaris 2.6 software.

Note -

Table 15-1 presents information based on the publicly available copies of the American National Standard for Information Systems - Programming Language XX3.159-1989, approved December 14, 1989.

Please note the following:

A "yes" in any column indicates that the option is supported by that compiler.

If the option has changed, the new option is listed.

A "no" in any column means the option is not supported by that driver

A "+" in the Sun WorkShop(TM) C++ 4.2 Solaris 2.6 column indicates an option required by SVID specifications.

Table 15-1 Comparison of C Compiler Options


Option or Flag	Sun C	ANSI C	Sun WorkShop(TM) C++ 4.2	Description
`-A` symbol	No	Yes	Yes	`cpp` predicate assertion
`-a`	Yes	Yes	`-xa`	Counts # basic block executions
`-align`	Yes	Yes	No	Page aligns (`ld`)
`-assertx`	Yes	Yes	`-z`	Specifies link-time assertion
`-BX`	Yes	Yes	Yes	Specifies binding type (only for libraries in SunOS release 5.6)
`-bnzero`	Yes	Yes	No	Generates nonzero AR
`-C`	Yes	Yes	No	`cpp` comments left in
`-c`	Yes	Yes	+Yes	Produces `.o` file
`-cg87`	Yes	Yes	No	Sets fp option to `-cg87`
`-cg89`	Yes	Yes	Yes	Sets fp option to `-cg89`
`-dryrun`	Yes	Yes	Yes	Shows commands constructed by driver
`-Dx`	Yes	Yes	+Yes	Defines `cpp` symbol x
`-d`	Yes	Yes	No	Forces definition of common (`ld`)
`-dalign`	Yes	Yes	Yes	Assumes doubles are double-word aligned
`-dl`	Yes	Yes	No	Generates long data segment refs
`-d[y\|n]`	`-BX`	`-BX`	Yes	Dynamic linking [yes\|no]
`-E`	Yes	Yes	+Yes	Runs source through `cpp`
`-e`	No	No	No	Entry point for ld
`-F`	`-O`*	`-O`*	+No	Optimization directives
`-f`	No	No	No	Floating-point support
`-fast`	Yes	Yes	Yes	Options for best performance
`-fsingle`	Yes	No	No	Floats are single precision
`-fsingle2`	Yes	No	No	Passes float (as float not double)
`-fnonstd`	Yes	Yes	Yes	Non-standard float option
`-fstore`	Yes	No	Yes	Forces writes on store
`-G`	No	No	Yes	Creates shared library, not available with the `-dn` option
`-g`	Yes	Yes	+Yes	Generates info for dbx
`-go`	Yes	No	No	Generates info for adb
`-H`	Yes	Yes	Yes	Prints paths of included files
`-h` name	No	No	Yes	Uses name as internal identifier; `soname` passed to linker
`-help`	Yes	Yes	`-flags`	Lists options
`-Ix`	Yes	Yes	+Yes	Adds x to include path
`-J`	sun3	No	No	Generates long offset for switch\|case
`-KPIC`	`-PIC`	`-PIC`	Yes	Position independent code
`-Kpic`	`-pic`	`-pic`	Yes	PIC with short offsets
`-Kminabi`	No	No	No	ABI compliant code
`-libmil`	Yes	Yes	`-xlibmil`	Passes `libm.il` as part of `-fast`
`-lx`	Yes	Yes	Yes	Reads object library (for ld)
`-Lx`	Yes	Yes	Yes	Adds x to ld library path
`-M`	Yes	Yes	No	Collects dependencies
`-M` `mapfile`	Yes	No	No	Passes `mapfile` to the linker
`-misalign`	Yes	Yes	Yes	Handles misaligned Sun-4 data
`-N`	Yes	No	No	Does not make shared
`-n`	Yes	No	No	Makes shared
`-native`	Yes	Yes	Yes	Uses appropriate `-cg` option
`-noc2`	Yes	Yes	No	Doesn't do peephole optimization
`-nolibmil`	Yes	Yes	`-xnolibmil`	Doesn't pass `libm.il` with `-fast`
`-o` file	Yes	Yes	+Yes	Sets name of output file
`-O[1,2,3,4]`	Yes	Yes	`-x0[1,2,3,4]`	Generates optimized code
`-O`	Yes	Yes	+Yes	Generates optimized code
`-P`	Yes	Yes	+Yes	Runs source through `cpp`, output to `.i`
`-PIC`	Yes	No	`-KPIC`	Generates pic code with long offset
`-p`	Yes	Yes	+Yes	Collects data for prof
`-pg`	Yes	Yes	`-xpg`	Collects data for gprof
`-pic`	Yes	Yes	`-Kpic`	pic code with short offset
`-pipe`	Yes	No	No	Uses pipes instead of temp files
`-purecross`	Yes	No	No	Doesn't have slash in VROOT
`-Qdir x`	Yes	Yes	`-Y*`	Looks for compiler passes in x
`-Qpath x`	Yes	Yes	`-Y*`	Same as `-Qdir`
`-Qn`	No	No	Yes	Doesn't add version stamp info
`-Qy`	No	No	Yes	Adds version stamp info
`-qdir` x	Yes	Yes	No	Looks for compiler passes in x
`-ql`	No	No	No	Collects data for lprof
`-qp`	`-p`	`-p`	`-p`	Collects data for prof
`-qpath` x	Yes	Yes	No	Same as `-Qdir`
`-Qoption` `cpp x`	Yes	Yes	Yes	Passes option x on to program `cpp`
`-Qoption` `iropt x`	Yes	Yes	Yes	Passes option x on to program iropt
`-Qoption` `cg x`	Yes	Yes	Yes	Passes option x on to program `cg`
`-Qoption` `inline x`	Yes	Yes	No	Passes option x on to program inline
`-Qoption` `as x`	Yes	Yes	No	Passes option x on to program `as`
`-Qoption` `asS x`	Yes	Yes	No	Passes option x on to program `asS`
`-Qoption` `ld x`	Yes	Yes	Yes	Passes option x on to program `ld`
`-qoption` `cpp x`	Yes	Yes	No	Passes option x on to program `cpp`
`-qoption` `ccom x`	Yes	Yes	No	Passes option x on to program `ccom`
`-qoption` `lintl x`	Yes	Yes	No	Passes option x on to program `lint1`
`-qoption` `iropt x`	Yes	Yes	Yes	Passes option x on to program `iropt`
`-qoption` `cg x`	Yes	Yes	Yes	Passes option x on to program `cg`
`-qoption` `inline x`	Yes	Yes	No	Passes option x on to program `inline`
`-qoption` `cat x`	Yes	Yes	No	Passes option x on to program `cat`
`-qoption` `c2 x`	Yes	Yes	No	Passes option x on to program `c2`
`-qoption` `as x`	Yes	Yes	No	Passes option x on to program `as`
`-qoption` `asS x`	Yes	Yes	No	Passes option x on to program `asS`
`-qoption` `ld x`	Yes	Yes	Yes	Passes option x on to program `ld`
`-Qproduce` `.o`	Yes	Yes	Yes	Produces type `.o` file (Object file)
`-Qproduce` `.s`	Yes	Yes	Yes	Produces type `.s` file (Assembler source)
`-Qproduce` `.c`	Yes	Yes	No	Produces type `.c` file (C source)
`-Qproduce` `.i`	Yes	Yes	Yes	Produces type `.i` file (C source after `cpp`)
`-qproduce` `.o`	Yes	Yes	Yes	Produces type `.o` file (Object file)
`-qproduce` `.s`	Yes	Yes	Yes	Produces type `.s` file (Assembler source)
`-qproduce` `.c`	Yes	Yes	No	Produces type `.c` file (C source)
`-qproduce` `.i`	Yes	Yes	Yes	Produces type `.i` file (C source after `cpp`)
`-r`	Yes	Yes	No	Makes relocatable; pass to linker
`-R`	Yes	Yes	No	Merges data into text segment
`-R`	No	No	Yes	Specifies search directories for the run-time linker
`-S`	Yes	Yes	+Yes	Produces `.s` file only
`-s`	Yes	Yes	Yes	Strips (4.1); pass to linker
`-sb`	Yes	Yes	`-xsb`	Collects information for code browser
`-strconst`	No	Yes	No	Places string literals in read-only text segment
`-sun2`	Yes	No	No	Generates code for a Sun-2(TM) system
`-sun3x`	Yes	No	No	Generates code for a Sun-3x(TM) system
`-sun386`	Yes	No	No	Generates code for a Sun386i(TM)
`-sun3`	Yes	No	No	Generates code for a Sun-3 system
`-sun4c`	Yes	No	No	Generates code for a Sun4c(TM) system
`-sun4`	Yes	No	No	Generates code for a Sun-4(TM) system
`-target`	Yes	No	`-xtarget`	Sets target architecture to x
`-temp=dir`	Yes	Yes	Yes	Set directory for temps to dir
`-time`	Yes	Yes	Yes	Reports the execution times
`-u`	Yes	Yes	No	Enters symbol arg as undef (ld)
`-Ux`	Yes	Yes	+Yes	Undefines `cpp` symbol x
`-v`	Yes	Yes	Yes	Verbose mode
`-v`	No	No	Yes	Strict semantic checking
`-V`	Yes	Yes	+Yes	Reports versions of programs
`-W`	No	No	No	Arguments to other components
`-w`	Yes	Yes	Yes	Does not print warnings
`-X[t,a,c,s]`	No	Yes	No	Compatibility options
`-Y`	No	No	No	Changes path name to components
`-yx`	Yes	No	No	Traces symbol
`-z`	`-assert`	`-assert`	No	Turns on asserts in linker
`-#`	`-v`	`-v`	No	Verbose mode
`-EOF`	No	No	No	File argument

The C compiler accepts the types of file-name arguments shown in Table 15-2.

Table 15-2 File-name Extensions Used by the C Compiler


Suffix	File Type
`.a`	Object library
`.il`	In-line expansion file
`.o`	Object file
`.so`	Shared object
`.s`	Assembler source
`.S`	Assembler source for `cpp`
`.c`	C source
`.i`	C source after `cpp`

"file.X=.Y" will read the file "file.X" but treat it as if it had suffix "Y"

Linkers

There are several changes to the link editor, ld(1), in this release. The most important change is its ability to handle the new ELF native file format.

Note -

The recommended method for building libraries and executables is through the compiler driver rather than by invoking the linker directly. The compiler automatically supplies several files needed by the linker.

Link Editor Option Differences

Some options have been renamed in the new linker, some have remained the same, and others are no longer needed. Table 15-3 compares the SunOS release 4.x ld command to the Solaris 2.6 ld command.

The sections following Table 15-3 explain how certain linking tasks are affected by the option differences.

Table 15-3 Comparison of ld Options


SunOS release 4.x Option	Solaris 2.6 Replacement	Notes
`-align` `datum`	`-M` `mapfile`	Uses `mapfile` and distinct sections
`-assert definitions`	Default
`-assert nodefinitions`	`-znodefs`	Issues a fatal error instead of a warning
`-assert nosymbolic`	`-zdefs`	Issues a fatal error instead of a warning
`-assert pure-text`	`-ztext`	Issues a fatal error instead of a warning
`-A` name	No replacement	`dlopen`(3X) and `dlclose`(3X) can approximate this behavior
`-Bdynamic`	`-Bdynamic`	Applies only to the inclusion of shared libraries; use `-dy` (the default) to build dynamically linked executables. See "Building Executables".
`-Bnosymbolic`	`-zdefs`
`-Bstatic`	`-dn` & `-Bstatic`	The `-dn` option must be specified to completely eliminate the dynamic linker. Use `-Bstatic` in dynamic mode to include archive libraries. (Used as a toggle. See "Building Executables".)
`-Bsymbolic`	`-Bsymbolic`	Also gets `-assert nosymbolic` with this option
`-d` `-dc` `-dp`	Default	Use `-b` option in SVR4 to turn off
`-D hex`	`-M` `mapfile`	`mapfile` contains different mechanisms to accomplish desired effect
`-e` `entry`	`-e` `entry`
no `-e`	`-G`	Creates a shared object
`-lx[.v]`	`-lx`	Only major number versioning of shared libraries is currently supported
`-Ldir`	`-Ldir`	`dir` not recorded in executable; use `-R` option instead.
`-M`	`-m`
`-n`	Default	SVR4 executable format compresses disk image as `-n`
`-N`	No replacement
`-o` `name`	`-o` `name`
`-p`	Default	Can override with `-M` `mapfile`
`-r`	`-r`
`-S`	No replacement
`-s`	`-s`
`-t`	No replacement
`-T` `hex`	`-M` `mapfile`	`mapfile` contains different mechanisms to accomplish desired effect
`-Tdata` `hex`	`-M` `mapfile`	`mapfile` contains different mechanisms to accomplish desired effect
`-u` `name`	`-u` `name`
`-x`	No replacement
`-X`	No replacement
`-y` `sym`	No replacement
`-z`	Default	SVR4 executable format demands pages as `-z`

Building Shared Libraries

The procedure for building shared librariesin the Solaris 2.6 operating environment requires the -G option. In the SunOS release 4.x software, the linker would infer that a shared library was being built by the absense of the -e option. As shared libraries may have entry points, this option can no longer be used.

Building Executables

The -Bdynamic and -Bstatic options are still available, but their behavior is different. These options now refer to library inclusions to the executable rather than binding. Executable binding is set exclusively with the new -dy and -dn options in the Solaris 2.6 software. The -dy option is the default. It is required to create a dynamically linked executable. The -dn option is required to create a statically linked executable.

The -Bdynamic and -Bstatic options apply only when using the -dy option. -Bdynamic tells the link editor to include shared libraries, while -Bstatic tells it to include archive libraries. These options act as a toggle governing subsequent -l arguments until the next -Bdynamic or -Bstatic option is encountered.

The following examples show SunOS release 4.x and Solaris 2.6 commands that can be used to create similar executables.

sunos4.1% ld -Bstatic test.o -lx

Uses libx.a and creates a static executable

sunos5.x% cc -dn test.o -lx

Uses libx.a and creates a static executable

sunos4.1% ld -Bdynamic test.o -lx

Uses libx.so and creates a dynamic executable

sunos5.x% cc test.o -lx

Uses libx.so and creates a dynamic executable

sunos4.1% ld -Bdynamic test.o -Bstatic -lx

Uses libx.a and creates a dynamic executable

sunos5.x% cc test.o -Bstatic -lx

Uses libx.a and creates a dynamic executable

Specifying Library Search Paths

In the SunOS release 4.x software, directories specified with the -L option were searched at link time and the information retained for use at execution time. This behavior is now divided between the -L and -R options. The -L option specifies the directories to search at link time; the -R option tells the linker the search paths to be retained for use at run time. See "Search Path Rules", in the next section for more information.

As with the -Bdynamic and -Bstatic options, the position of the -L option has significance; it applies only to the subsequent -l options.

Search Path Rules

The dynamic linker and the runtime linker determine their search paths through a different algorithm from that used by the SunOS release 4.x linker.

The examples below compare the search paths for the dynamic linker and the runtime linker for SunOS release 4.x and the Solaris 2.6 operating environment. Notice that in the latter, the search path for the link editor and the runtime linker are affected by the LD_LIBRARY_PATH setting.

SunOS release 4.x linker search paths:

Link Editor: -L, LD_LIBRARY_PATH, /usr/lib, /usr/local/lib
Runtime Linker: LD_LIBRARY_PATH, -L, /usr/lib, /usr/local/lib

Solaris 2.6 linker search paths (with LD_LIBRARY_PATH=dirlist1):

Link Editor: -L, dirlist1, /usr/ccs/lib, /usr/lib
Runtime Linker: dirlist1, -R, /usr/lib

Solaris 2.6 linker search paths (with LD_LIBRARY_PATH=dirlist1,dirlist2):

Link Editor: dirlist1, -L, dirlist2, /usr/ccs/lib, /usr/lib

Runtime Linker: dirlist1, dirlist2, -R, /usr/lib

Version Numbering

The SunOS release 4.x software supported both major and minor version numbers on shared libraries. The Solaris 2.6 operating environment supports only the major version number. For binary compatibility support, major and minor version numbers are recognized on SunOS release 4.x shared libraries. These libraries are required to retain the same major and minor version number they had in the SunOS release 4.x software.

Table 15-4 shows versions of SunOS release 4.x and Solaris 2.6 shared libraries.

Table 15-4 Example Shared Libraries


SunOS release 4.x	Solaris 2.6
`libc.so.1.7`	`libc.so.1`
`libdl.so.1.0`	`libdl.so.1`

In SunOS release 4.x system software, when the -l option was specified, the build environment linker searched for a library with both major and minor numbers. For example, if -ldl was specified, the library, libdl.so.1.0 was linked. In the Solaris 2.6 environment, even though major numbers are still supported, the default behavior of the link editor is to ignore version numbers. Using the previous example, the build environment link editor now searches for libdl.so and a symbolic link points to a specific version file.

The recording of a dependency in a dynamic executable or shared object is, by default, the file name of the associated shared object as it is referenced by the link editor. To provide a more consistent means of specifying dependencies, shared objects can record within themselves the file name by which they should be referenced at runtime. This is specified with the -h option when linking the library file.

Symbolic links have been created for most libraries in this release. You should build any new shared libraries with major numbers, then create a symbolic link to the version of the library that is used most often.

Examples

A new utility, dump(1), makes it easier to debug object files or to check the static and dynamic linking, see "Backing Up and Restoring Files"). The dump -L option displays the information needed by the runtime linker that is contained in the executable. This information is contained in the dynamic section of an ELF file. The RPATH entry displays search paths specified by the -R option to ld.

The following example:

Builds a shared library, libx.so.1, using libx.o

Creates a link from libx.so.1 to libx.so

Shows dump output, including the SONAME field, which stores the information passed with the -h option.

examples% cc -G -o libx.so.1 -h libx.so.1 libx.o

examples% cp libx.so.1 /mylibs
examples% ln -s /mylibs/libx.so.1 /mylibs/libx.so
examples% dump -Lv libx.so.1

libx.so.1:

  **** DYNAMIC SECTION INFORMATION ****
.dynamic :
[INDEX] Tag      Value
[1]     INIT     0x3b8
[2]     FINI     0x3f4
[3]     SONAME   libx.so.1
[4]     HASH     0x94
[5]     STRTAB   0x33c
[6]     SYMTAB   0x14c
[7]     STRSZ    0x62
[8]     SYMENT   0x10
[9]     PLTGOT   0x10404
[10]    PLTSZ    0xc
[11]    PLTREL   0x7
[12]    JMPREL   0x3ac
[13]    RELA     0x3a0
[14]    RELASZ   0x18
[15]    RELAENT  0xc

If a library needs other dynamic libraries, they should be specified along with an RPATH, as the next example shows.

The next example compiles prog.c, dynamically linking libx.so (as built in the previous example), and specifies that the binary retain the current directory information for execution. This example shows the output of dump from the compiled program, prog.c. Here, the information stored in the SONAME field of the previous example is shown as NEEDED by prog. When prog is run, it will use libx.so.1 even if libx.so is linked to a different version.

examples% cc -o prog prog.c -L/mylibs -R/mylibs -lx
example% dump -Lv prog

prog:

  **** DYNAMIC SECTION INFORMATION ****
.dynamic :
[INDEX]   Tag   Value
[1]  NEEDED   libx.so.1
[2]  NEEDED   libc.so.1
[3]  INIT     0x1b1ac
[4]  FINI     0x1b248
[5]  RPATH    /mylibs
[6]  HASH     0x100e8
[7]  STRTAB   0x17f90
[8]  SYMTAB   0x12be0
[9]  STRSZ    0x31e1
[10] SYMENT   0x10
[11] DEBUG    0x0
[12] PLTGOT   0x2b25c
[13] PLTSZ    0x30
[14] PLTREL   0x7
[15] JMPREL   0x1b180
[16] RELA     0x1b174
[17] RELASZ   0x3c
[18] RELAENT  0xc

Debuggers

This section describes changes to debugging tools.

`dbx` and `dbxtool`

The dbx and dbxtool tools are no longer available with default system software. Enhanced versions of these tools are available as part of Sun WorkShop(TM), an unbundled product.

`adb` and `kadb`

The adb and kadb tools are available in the Solaris 2.6 operating environment. They offer the same capabilities as the SunOS release 4.x tools. kadb has been enhanced to recognize multiple processors. The processor ID is displayed in the kadb prompt. In the following examples, it is 0.

To make kernel debugging under the Solaris 2.6 operating environment easier:

Enable savecore (uncomment the savecore lines in the /etc/init.d/sysetup file)

Boot under kadb (type $c when the system crashes)

Use adb and crash

`kadb` Macros

The kadb macros described below are particularly useful with the new multithreaded kernel.

thread displays the current thread. The current thread pointer is in SPARC global register g7.

kadb[0]: <g7$<thread

threadlist shows the stack traces of all the kernel threads in the system. This can be a long list.

kadb[0]: $<threadlist

mutex shows you the address of the owning thread. The following example uses the global unsafe driver mutex.

kadb[0]: unsafe_driver$<mutex

kadb[0]: moddebug/W 0x80000000

`moddebug`

moddebug enables you to watch module loading. See the end of <sys/modctl.h> for legal values for moddebug for debugging purposes only.

Debugging a Live Kernel

Use the following command to debug a live kernel.

# adb -k /dev/ksyms /dev/mem

/dev/ksyms is a pseudo device that contains the complete name list of the running kernel.

`truss` Command

truss is a new utility, provided to trace system calls performed, signals received, and machine faults incurred. truss offers several significant improvements over the SunOS release 4.x trace(1) command, including the ability to follow forked processes and to deal with multithreaded processes.

The following example shows a summary of traced calls for the date command. With the -c option, truss does not display the trace line by line. Instead, it counts the system calls, signals, and faults, and displays a summary.

example% truss -c date
Fri Sep 18 14:31:30 PDT 1992
syscall      seconds   calls  errors
_exit            .00       1
read             .00       7
write            .00       1
open             .03      12
close            .00      12
time             .00       1
brk              .01       4
lseek            .00       1
fstat            .00       4
ioctl            .00       1
execve           .00       1
mmap             .01      17
munmap           .00       8
                ----     ---    ---
sys totals:      .05      70      0
usr time:        .03
elapsed:         .28

See the truss(1) man page for complete details on all truss options. There are a number of other Solaris 2.6 debugging tools based on proc(4) such as pmap(1).