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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 unforeseen 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.
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 kldload 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
146 it with additional STREAMS
147 state information before returning it to the client application.
150 environment uses the additional state information to recognize and
151 manipulate emulated STREAMS handles when STREAMS-specific
155 The subset of STREAMS functionality which is provided is small, probably
156 little more than what is required to enable programs on the Solaris CD
159 .Bl -tag -width /sys/compat/svr4/syscalls.master -compact
161 minimal SVR4 run-time environment
162 .It Pa /sys/compat/svr4/syscalls.master
163 mappings between SVR4 syscalls and
172 System V Release 4 ABI support first appeared in
174 The ABI was ported from an equivalent facility present in
176 written by Christos Zoulas.
178 Emulation of signal handlers is buggy.
180 Emulated connectionless STREAMS fail to receive data from the network in
181 some circumstances (but succeed in others -- probably due to particular
182 ways of initializing them which the
184 module is mishandling, and interaction between STREAMS and
186 Connection-oriented STREAMS appear to be functional.
188 Ironically, this SVR4 emulator does not (yet) support SVR4 semaphores or
192 to automatically create the
194 environment do not exist.
196 archives containing pre-populated trees can be obtained from
197 .Pa http://people.FreeBSD.org/~newton/freebsd-svr4/ .
199 Extensive testing has only really been carried out with Solaris 2.x binaries,
200 with anecdotal reports of limited success coming from testers with
201 early-revision SCO media.
202 In theory, the basic SVR4 ABI should be constant
203 across the set of vendors who produce SVR4 operating systems, but in
204 practice that is probably not the case.
205 If necessary, future work can
206 either implement additional
208 modules which produce functionality which contains OS-dependent
209 departures from the behaviour which has been implemented in this
213 variables could set the
215 the environment should present to