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+[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts.  A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+[[!meta title="Doing a GNU/Hurd System Port"]]
+
+How difficult is it to port the GNU/Hurd system to run on another architecture?
+
+The GNU/Hurd system consists of [[/Hurd]] servers running as user-space
+processes on top of the [[GNU Mach|microkernel/mach/gnumach]] microkernel.  The
+system functionality is usually accessed through the
+[[POSIX|posix_compatibility]] interface that is provided by [[/glibc]] and
+[[/libpthread]].
+
+A whole-system port involves touching all these components, with varying
+degree, of course.
+
+For a CPU architecture port, the microkernel is the most involved part,
+followed by glibc and the threading library.
+
+The original [[microkernel/Mach]] microkernel was portable to a number of
+architectures which were a lot more popular at the beginning of the 1990s than
+they are now.
+
+The GNU/Hurd system is currently available for the x86 architecture.  This
+includes emulators such as [[hurd/running/QEMU]] (or KVM), or
+[[hurd/running/VirtualBox]].  Besides this, there is a port for the [[Xen
+domU|microkernel/mach/gnumach/ports/xen]] *sub-architecture*.
+
+Further on, there are some [[unfinished porting
+attempts|microkernel/mach/gnumach/ports]] for the Alpha, MIPS and PowerPC
+architectures.  These have not been completed due to little developer interest.
+
+Another option is to do the port at a different layer: port the Hurd servers to
+not run on the GNU Mach microkernel, but instead on top of [[another
+microkernel|which_microkernel]].  Or, even by providing a Mach emulation layer
+on top of a monolithic kernel.  For example, there could be a port for [[having
+Mach run as a POSIX user-space process|open_issues/mach_on_top_of_posix]], or
+by implementing the [[Mach IPC|microkernel/mach/ipc]] facility (as well as
+several others) as Linux kernel modules.  While there have been some
+experiments, no such port has been completed yet.