Native Conditionals
*******************

   When GDB is configured and compiled, various macros are defined or
left undefined, to control compilation when the host and target systems
are the same.  These macros should be defined (or left undefined) in
`nm-SYSTEM.h'.

`ATTACH_DETACH'
     If defined, then GDB will include support for the `attach' and
     `detach' commands.

`CHILD_PREPARE_TO_STORE'
     If the machine stores all registers at once in the child process,
     then define this to ensure that all values are correct.  This
     usually entails a read from the child.

     [Note that this is incorrectly defined in `xm-SYSTEM.h' files
     currently.]

`FETCH_INFERIOR_REGISTERS'
     Define this if the native-dependent code will provide its own
     routines `fetch_inferior_registers' and `store_inferior_registers'
     in `HOST-nat.c'.  If this symbol is *not* defined, and
     `infptrace.c' is included in this configuration, the default
     routines in `infptrace.c' are used for these functions.

`GET_LONGJMP_TARGET'
     For most machines, this is a target-dependent parameter.  On the
     DECstation and the Iris, this is a native-dependent parameter,
     since <setjmp.h> is needed to define it.

     This macro determines the target PC address that longjmp() will
     jump to, assuming that we have just stopped at a longjmp
     breakpoint.  It takes a CORE_ADDR * as argument, and stores the
     target PC value through this pointer.  It examines the current
     state of the machine as needed.

`PROC_NAME_FMT'
     Defines the format for the name of a `/proc' device.  Should be
     defined in `nm.h' *only* in order to override the default
     definition in `procfs.c'.

`PTRACE_FP_BUG'
     mach386-xdep.c

`PTRACE_ARG3_TYPE'
     The type of the third argument to the `ptrace' system call, if it
     exists and is different from `int'.

`REGISTER_U_ADDR'
     Defines the offset of the registers in the "u area"; see Host..

`SOLIB_ADD (filename, from_tty, targ)'
     Define this to expand into an expression that will cause the
     symbols in FILENAME to be added to GDB's symbol table.

`SOLIB_CREATE_INFERIOR_HOOK'
     Define this to expand into any shared-library-relocation code that
     you want to be run just after the child process has been forked.

`START_INFERIOR_TRAPS_EXPECTED'
     When starting an inferior, GDB normally expects to trap twice;
     once when the shell execs, and once when the program itself execs.
     If the actual number of traps is something other than 2, then
     define this macro to expand into the number expected.

`USE_PROC_FS'
     This determines whether small routines in `*-tdep.c', which
     translate register values between GDB's internal representation
     and the /proc representation, are compiled.

`U_REGS_OFFSET'
     This is the offset of the registers in the upage.  It need only be
     defined if the generic ptrace register access routines in
     `infptrace.c' are being used (that is, `infptrace.c' is configured
     in, and `FETCH_INFERIOR_REGISTERS' is not defined).  If the
     default value from `infptrace.c' is good enough, leave it
     undefined.

     The default value means that u.u_ar0 *points to* the location of
     the registers.  I'm guessing that `#define U_REGS_OFFSET 0' means
     that u.u_ar0 *is* the location of the registers.

`CLEAR_SOLIB'
     objfiles.c

`DEBUG_PTRACE'
     Define this to debug ptrace calls.