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31 .Nd System V Release 4 ABI support
33 To link System V Release 4 (SVR4) ABI support into the kernel:
34 .Cd options COMPAT_SVR4
36 To load the SVR4 ABI support kernel module:
41 module provides limited
42 System V Release 4 ABI (application binary interface) compatibility
43 for userland applications.
44 The module provides the following significant facilities:
52 Special signal handling for activated images
54 SVR4 to native system call translation
56 STREAMS network API emulation (via the
58 loadable module, or by means of
60 in a kernel configuration file)
66 calls, or, where no such mappings exist, reverse-engineered implementations
70 It is important to note that the SVR4 ABI support
71 it not provided through an emulator.
72 Rather, a true (albeit limited) "clean room" reverse-engineered ABI
73 implementation is provided.
75 Because the provided ABI has been developed in ignorance of actual SVR4
76 source code, there are bound to be unforseen interactions between SVR4
77 client applications and the emulated ABI which cause applications to
80 Additionally, some SVR4 operating systems do not adhere to the SVR4
82 In particular, Solaris does not set the ELF interpreter field in the
83 ELF header to a value which would allow the kernel to correctly
84 identify a client executable as an SVR4 application.
85 Thus, in certain instances it is necessary to use the
87 utility to explicitly brand the executable, or to set the
88 kern.fallback_elf_brand
90 variable to define a "default" ABI for unbranded executables.
91 Value ELFOSABI_SOLARIS represents Solaris; ELFOSABI_SYSV represents other
92 SysVR4 operating systems.
94 .Pa /usr/include/sys/elf_common.h
95 for ELFOSABI branding definitions, and
97 for information on branding executables.
101 module can be linked into the kernel statically with the
103 kernel configuration option
104 or loaded as required.
105 The following command will load the module
106 if it is neither linked into the kernel
107 nor already loaded as a module:
108 .Bd -literal -offset indent
109 if ! kldstat -v | grep -E 'svr4elf' > /dev/null; then
110 /usr/bin/svr4 > /dev/null 2>&1
115 will check for the presence of the
117 module, and load it if necessary.
119 Note that dynamically linked SVR4 executables
120 will require a suitable environment in
123 For information on loading the
125 kernel loadable module automatically on system startup,
128 This information applies
129 regardless of whether the
131 module is statically linked into the kernel
132 or loaded as a module.
134 STREAMS emulation is limited but (largely) functional.
137 module is loaded, a STREAMS handle can be obtained by opening one of the
141 .Pa /compat/svr4/dev .
144 driver produces a socket descriptor and "tags" it with additional STREAMS
145 state information before returning it to the client application.
148 environment uses the additional state information to recognize and
149 manipulate emulated STREAMS handles when STREAMS-specific
153 The subset of STREAMS functionality which is provided is small, probably
154 little more than what is required to enable programs on the Solaris CD
157 Emulation of signal handlers is buggy.
159 Emulated connectionless STREAMS fail to receive data from the network in
160 some circumstances (but succeed in others -- probably due to particular
161 ways of initializing them which the
163 module is mishandling, and interaction between STREAMS and
165 Connection-oriented STREAMS appear to be functional.
167 Ironically, this SVR4 emulator does not (yet) support SVR4 semaphores or
171 to automatically create the
173 environment do not exist.
175 archives containing pre-populated trees can be obtained from
176 .Pa http://people.freebsd.org/~newton/freebsd-svr4/ .
178 Extensive testing has only really been carried out with Solaris 2.x binaries,
179 with anecdotal reports of limited success coming from testers with
180 early-revision SCO media. In theory, the basic SVR4 ABI should be constant
181 across the set of vendors who produce SVR4 operating systems, but in
182 practice that's probably not the case. If necessary, future work can
183 either implement additional
185 modules which produce functionality which contains OS-dependent
186 departures from the behaviour which has been implemented in this
190 variables could set the "personality" the environment should present to
193 .Bl -tag -width /sys/compat/svr4/syscalls.master -compact
195 minimal SVR4 run-time environment
196 .It Pa /sys/compat/svr4/syscalls.master
197 mappings between SVR4 syscalls and
206 System V Release 4 ABI support first appeared in
208 The ABI was ported from an equivalent facility present in
210 written by Christos Zoulas.