+ int offset;
+
+ /* To support the recognition of signal handlers, i386bsd-tdep.c
+ hardcodes some constants. Inclusion of this file means that we
+ are compiling a native debugger, which means that we can use the
+ system header files and sysctl(3) to get at the relevant
+ information. */
+
+#if defined (__FreeBSD_version) && __FreeBSD_version >= 400011
+#define SC_REG_OFFSET i386fbsd4_sc_reg_offset
+#elif defined (__FreeBSD_version) && __FreeBSD_version >= 300005
+#define SC_REG_OFFSET i386fbsd_sc_reg_offset
+#elif defined (NetBSD) || defined (__NetBSD_Version__)
+#define SC_REG_OFFSET i386nbsd_sc_reg_offset
+#elif defined (OpenBSD)
+#define SC_REG_OFFSET i386obsd_sc_reg_offset
+#endif
+
+#ifdef SC_REG_OFFSET
+
+ /* We only check the program counter, stack pointer and frame
+ pointer since these members of `struct sigcontext' are essential
+ for providing backtraces. More checks could be added, but would
+ involve adding configure checks for the appropriate structure
+ members, since older BSD's don't provide all of them. */
+
+#define SC_PC_OFFSET SC_REG_OFFSET[I386_EIP_REGNUM]
+#define SC_SP_OFFSET SC_REG_OFFSET[I386_ESP_REGNUM]
+#define SC_FP_OFFSET SC_REG_OFFSET[I386_EBP_REGNUM]
+
+ /* Override the default value for the offset of the program counter
+ in the sigcontext structure. */
+ offset = offsetof (struct sigcontext, sc_pc);
+
+ if (SC_PC_OFFSET != offset)
+ {
+ warning (_("\
+offsetof (struct sigcontext, sc_pc) yields %d instead of %d.\n\
+Please report this to <bug-gdb@gnu.org>."),
+ offset, SC_PC_OFFSET);
+ }
+
+ SC_PC_OFFSET = offset;
+
+ /* Likewise for the stack pointer. */
+ offset = offsetof (struct sigcontext, sc_sp);
+
+ if (SC_SP_OFFSET != offset)
+ {
+ warning (_("\
+offsetof (struct sigcontext, sc_sp) yields %d instead of %d.\n\
+Please report this to <bug-gdb@gnu.org>."),
+ offset, SC_SP_OFFSET);
+ }
+
+ SC_SP_OFFSET = offset;
+
+ /* And the frame pointer. */
+ offset = offsetof (struct sigcontext, sc_fp);
+
+ if (SC_FP_OFFSET != offset)
+ {
+ warning (_("\
+offsetof (struct sigcontext, sc_fp) yields %d instead of %d.\n\
+Please report this to <bug-gdb@gnu.org>."),
+ offset, SC_FP_OFFSET);
+ }
+
+ SC_FP_OFFSET = offset;
+
+#endif /* SC_REG_OFFSET */