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

Fri Jul 13 13:19:23 UTC 2018

This looks fine to push

On Fri, Jul 13, 2018 at 3:32 AM, Amaan Cheval <amaan.cheval at gmail.com> wrote:
> ---
>  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 +Quick instructions (which may fall out of date) are: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
>