[PATCH 1/1] user: Add x86_64 BSP chapter

Fri Jul 13 07:32:27 UTC 2018

---
 user/bsps/bsps-x86_64.rst | 143 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 142 insertions(+), 1 deletion(-)

diff --git a/user/bsps/bsps-x86_64.rst b/user/bsps/bsps-x86_64.rst
index 18f80d2..19c4461 100644
--- a/user/bsps/bsps-x86_64.rst
+++ b/user/bsps/bsps-x86_64.rst
@@ -1,7 +1,148 @@
 .. comment SPDX-License-Identifier: CC-BY-SA-4.0
+.. comment Copyright (c) 2018 Amaan Cheval <amaan.cheval at gmail.com>
 .. comment Copyright (c) 2018 embedded brains GmbH
 
 x86_64
 ******
 
-There are no x86_64 BSPs yet.
+amd64
+=====
+
+This BSP offers only one variant, ``amd64``. The BSP can run on UEFI-capable
+systems by using FreeBSD's bootloader, which then loads the RTEMS executable (an
+ELF image).
+
+Currently only the console driver and context initialization and switching are
+functional (to a bare minimum), but this is enough to run the ``hello.exe`` sample
+in the RTEMS testsuite.
+
+Build Configuration Options
+---------------------------
+
+There are no options available to ``configure`` at build time, at the moment.
+
+Testing with QEMU
+-----------------
+
+To test with QEMU, we need to:
+
+- Build / install QEMU (most distributions should have it available on the
+  package manager).
+- Build UEFI firmware that QEMU can use to simulate an x86-64 system capable of
+  booting a UEFI-aware kernel, through the ``--bios`` flag.
+
+Building TianoCore's UEFI firmware, OVMF
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Complete detailed instructions are available at `TianoCore's Github's wiki
+<https://github.com/tianocore/tianocore.github.io/wiki/How-to-build-OVMF>`_.
+
+Quick instructions (which may fall out of date) are:
+
+.. code-block:: shell
+
+    $ git clone git://github.com/tianocore/edk2.git
+    $ cd edk2
+    $ make -C BaseTools
+    $ . edksetup.sh
+
+Then edit ``Conf/target.txt`` to set:
+
+::
+
+    ACTIVE_PLATFORM       = OvmfPkg/OvmfPkgX64.dsc
+    TARGET                = DEBUG
+    TARGET_ARCH           = X64
+    # You can use GCC46 as well, if you'd prefer
+    TOOL_CHAIN_TAG        = GCC5
+
+Then run ``build`` in the ``edk2`` directory - the output should list the
+location of the ``OVMF.fd`` file, which can be used with QEMU to boot into a UEFI
+shell.
+
+You can find the ``OVMF.fd`` file like this as well in the edk2 directory:
+
+.. code-block:: shell
+
+    $ find . -name "*.fd"
+    ./Build/OvmfX64/DEBUG_GCC5/FV/MEMFD.fd
+    ./Build/OvmfX64/DEBUG_GCC5/FV/OVMF.fd <-- the file we're looking for
+    ./Build/OvmfX64/DEBUG_GCC5/FV/OVMF_CODE.fd
+    ./Build/OvmfX64/DEBUG_GCC5/FV/OVMF_VARS.fd
+
+Boot RTEMS via FreeBSD's bootloader
+-----------------------------------
+
+The RTEMS executable produced (an ELF file) needs to be placed in the FreeBSD's
+``/boot/kernel/kernel``'s place.
+
+To do that, we first need a hard-disk image with FreeBSD installed on
+it. `Download FreeBSD's installer "memstick" image for amd64
+<https://www.freebsd.org/where.html>`_ and then run the following commands,
+replacing paths as appropriate.
+
+.. code-block:: shell
+
+   $ qemu-img create freebsd.img 8G
+   $ OVMF_LOCATION=/path/to/ovmf/OVMF.fd
+   $ FREEBSD_MEMSTICK=/path/to/FreeBSD-11.2-amd64-memstick.img
+   $ qemu-system-x86_64 -m 1024 -serial stdio --bios $OVMF_LOCATION \
+       -drive format=raw,file=freebsd.img \
+       -drive format=raw,file=$FREEBSD_MEMSTICK
+
+The first time you do this, continue through and install FreeBSD. `FreeBSD's
+installation guide may prove useful
+<https://www.freebsd.org/doc/handbook/bsdinstall-start.html>`_ if required.
+
+Once installed, build your RTEMS executable (an ELF file), for
+eg. ``hello.exe``. We need to transfer this executable into ``freebsd.img``'s
+filesystem, at either ``/boot/kernel/kernel`` or ``/boot/kernel.old/kernel`` (or
+elsewhere, if you don't mind user FreeBSD's ``loader``'s prompt to boot your
+custom kernel).
+
+If your host system supports mounting UFS filesystems as read-write
+(eg. FreeBSD), go ahead and:
+
+1. Mount ``freebsd.img`` as read-write
+2. Within the filesystem, back the existing FreeBSD kernel up (i.e. effectively
+   ``cp -r /boot/kernel /boot/kernel.old``).
+3. Place your RTEMS executable at ``/boot/kernel/kernel``
+
+If your host doesn't support mounting UFS filesystems (eg. most Linux kernels),
+do something to the effect of the following.
+
+On the host
+
+.. code-block:: shell
+
+   # Upload hello.exe anywhere accessible within the host
+   $ curl --upload-file hello.exe https://transfer.sh/rtems
+
+Then on the guest (FreeBSD), login with ``root`` and
+
+.. code-block:: shell
+
+   # Back the FreeBSD kernel up
+   $ cp -r /boot/kernel/ /boot/kernel.old
+   # Bring networking online if it isn't already
+   $ dhclient em0
+   # You may need to add the --no-verify-peer depending on your server
+   $ fetch https://host.com/path/to/rtems/hello.exe
+   # Replace default kernel
+   $ cp hello.exe /boot/kernel/kernel
+   $ reboot
+
+After rebooting, the RTEMS kernel should run after the UEFI firmware and
+FreeBSD's bootloader. The ``-serial stdio`` QEMU flag will let the RTEMS console
+send its output to the host's ``stdio`` stream.
+
+Clock Driver
+------------
+
+The clock driver currently uses the idle thread clock driver.
+
+Console Driver
+--------------
+
+The console driver defaults to using the ``COM1`` UART port (at I/O port
+``0x3F8``), using the ``NS16550`` polled driver.
-- 
2.16.0.rc0


