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

Wed Jul 18 17:40:35 UTC 2018

Ping -- joel

On Fri, Jul 13, 2018 at 9:19 AM, Gedare Bloom <gedare at rtems.org> wrote:
> 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 +Quick instructions (which may fall out of date) are: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
>>