fs/Kconfig.binfmt v3.0-rc7


Kernel support for ELF binaries

ELF (Executable and Linkable Format) is a format for libraries and
executables used across different architectures and operating
systems. Saying Y here will enable your kernel to run ELF binaries
and enlarge it by about 13 KB. ELF support under Linux has now all
but replaced the traditional Linux a.out formats (QMAGIC and ZMAGIC)
because it is portable (this does *not* mean that you will be able
to run executables from different architectures or operating systems
however) and makes building run-time libraries very easy. Many new
executables are distributed solely in ELF format. You definitely
want to say Y here.

Information about ELF is contained in the ELF HOWTO available from

If you find that after upgrading from Linux kernel 1.2 and saying Y
here, you still can't run any ELF binaries (they just crash), then
you'll have to install the newest ELF runtime libraries, including
ld.so (check the file <file:Documentation/Changes> for location and
latest version).


Kernel support for FDPIC ELF binaries

ELF FDPIC binaries are based on ELF, but allow the individual load
segments of a binary to be located in memory independently of each
other. This makes this format ideal for use in environments where no
MMU is available as it still permits text segments to be shared,
even if data segments are not.

It is also possible to run FDPIC ELF binaries on MMU linux also.


Write ELF core dumps with partial segments

ELF core dump files describe each memory mapping of the crashed
process, and can contain or omit the memory contents of each one.
The contents of an unmodified text mapping are omitted by default.

For an unmodified text mapping of an ELF object, including just
the first page of the file in a core dump makes it possible to
identify the build ID bits in the file, without paying the i/o
cost and disk space to dump all the text.  However, versions of
GDB before 6.7 are confused by ELF core dump files in this format.

The core dump behavior can be controlled per process using
the /proc/PID/coredump_filter pseudo-file; this setting is
inherited.  See Documentation/filesystems/proc.txt for details.

This config option changes the default setting of coredump_filter
seen at boot time.  If unsure, say Y.


Kernel support for flat binaries

Support uClinux FLAT format binaries.


Enable ZFLAT support

Support FLAT format compressed binaries


Enable shared FLAT support

Support FLAT shared libraries


Kernel support for a.out and ECOFF binaries

A.out (Assembler.OUTput) is a set of formats for libraries and
executables used in the earliest versions of UNIX.  Linux used
the a.out formats QMAGIC and ZMAGIC until they were replaced
with the ELF format.

The conversion to ELF started in 1995.  This option is primarily
provided for historical interest and for the benefit of those
who need to run binaries from that era.

Most people should answer N here.  If you think you may have
occasional use for this format, enable module support above
and answer M here to compile this support as a module called

If any crucial components of your system (such as /sbin/init
or /lib/ld.so) are still in a.out format, you will have to
say Y here.


OSF/1 v4 readv/writev compatibility

Say Y if you are using OSF/1 binaries (like Netscape and Acrobat)
with v4 shared libraries freely available from Compaq. If you're
going to use shared libraries from Tru64 version 5.0 or later, say N.


Kernel support for Linux/Intel ELF binaries

Say Y here if you want to be able to execute Linux/Intel ELF
binaries just like native Alpha binaries on your Alpha machine. For
this to work, you need to have the emulator /usr/bin/em86 in place.

You can get the same functionality by saying N here and saying Y to
"Kernel support for MISC binaries".

You may answer M to compile the emulation support as a module and
later load the module when you want to use a Linux/Intel binary. The
module will be called binfmt_em86. If unsure, say Y.


Kernel support for SOM binaries

SOM is a binary executable format inherited from HP/UX.  Say
Y here to be able to load and execute SOM binaries directly.


Kernel support for MISC binaries

If you say Y here, it will be possible to plug wrapper-driven binary
formats into the kernel. You will like this especially when you use
programs that need an interpreter to run like Java, Python, .NET or
Emacs-Lisp. It's also useful if you often run DOS executables under
the Linux DOS emulator DOSEMU (read the DOSEMU-HOWTO, available from
<http://www.tldp.org/docs.html#howto>). Once you have
registered such a binary class with the kernel, you can start one of
those programs simply by typing in its name at a shell prompt; Linux
will automatically feed it to the correct interpreter.

You can do other nice things, too. Read the file
<file:Documentation/binfmt_misc.txt> to learn how to use this
feature, <file:Documentation/java.txt> for information about how
to include Java support. and <file:Documentation/mono.txt> for
information about how to include Mono-based .NET support.

To use binfmt_misc, you will need to mount it:
mount binfmt_misc -t binfmt_misc /proc/sys/fs/binfmt_misc

You may say M here for module support and later load the module when
you have use for it; the module is called binfmt_misc. If you
don't know what to answer at this point, say Y.