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-m, -mapped
Warning: this option depends on operating system facilities
that are not supported on all systems.
If memory-mapped files are available on your system
through the mmap system call, you can use this option
to have GDB write the symbols from your program
into a reusable file in the current directory. If the
program you are debugging is called '/tmp/fred', the
mapped symbol file is '/tmp/fred.syms'. Future GDB
debugging sessions notice the presence of this file, and
can quickly map in symbol information from it, rather
than reading the symbol table from the executable
program.
The '.syms' file is specific to the host machine where
GDB is run. It holds an exact image of the internal GDB
symbol table. It cannot be shared across multiple host
platforms.
-r, -readnow
Read each symbol file's entire symbol table
immediately, rather than the default, which is to read
it incrementally as it is needed. This makes startup
slower, but makes future operations faster.
You typically combine the -mapped and -readnow options in order to build a '.syms'
file that contains complete symbol information. (See “Commands to specify files”
(page 125), for information on '.syms' files.) A simple GDB invocation to do nothing
but build a '.syms' file for future use is:
gdb -batch -nx -mapped -readnow programname
2.1.2 Choosing modes
You can run GDB in various alternative modes―for example, in batch mode or quiet
mode.
-nx, -n
Do not execute commands found in any initialization
files (normally called '.gdbinit', or 'gdb.ini' on PCs).
Normally, GDB executes the commands in these files
after all the command options and arguments have been
processed. See “Command files” (page 289).
-quiet, -silent, -q
“Quiet”. Do not print the introductory and copyright
messages. These messages are also suppressed in batch
mode.
-batch Run in batch mode. Exit with status 0 after processing
all the command files specified with '-x' (and all
commands from initialization files, if not inhibited with
2.1 Invoking GDB 27