Re: [PATCH v4 edk2-platforms 20/23] Platform/Raspberry/Pi3: Add platform readme

[Leif Lindholm <leif.lindholm@linaro.org>]

Hi Pete,

I will only have minor comments on this set, but I'll start with this
documentation.

On Tue, Jan 29, 2019 at 04:26:52PM +0000, Pete Batard wrote:
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Pete Batard <pete@akeo.ie>
> ---
>  Platform/Raspberry/Pi3/Readme.md | 259 ++++++++++++++++++++
>  Readme.md                        |   3 +
>  2 files changed, 262 insertions(+)
> 
> diff --git a/Platform/Raspberry/Pi3/Readme.md b/Platform/Raspberry/Pi3/Readme.md
> new file mode 100644
> index 000000000000..7fb59ccdc321
> --- /dev/null
> +++ b/Platform/Raspberry/Pi3/Readme.md
> @@ -0,0 +1,259 @@
> +Raspberry Pi 3 EDK2 Platform Support
> +====================================
> +
> +# Summary
> +
> +This is a port of 64-bit Tiano Core UEFI firmware for the Raspberry Pi 3/3B+ platforms,
> +based on [Ard Bisheuvel's 64-bit](http://www.workofard.com/2017/02/uefi-on-the-pi/)
> +and [Microsoft's 32-bit](https://github.com/ms-iot/RPi-UEFI/tree/ms-iot/Pi3BoardPkg)
> +implementations, as maintained by [Andrei Warkentin](https://github.com/andreiw/RaspberryPiPkg).
> +
> +This is meant as a generally useful 64-bit ATF + UEFI implementation for the Raspberry
> +Pi 3/3B+ which should be good enough for most kind of UEFI development, as well as for
> +running consummer Operating Systems in such as Linux or Windows.
> +
> +Raspberry Pi is a trademark of the [Raspberry Pi Foundation](http://www.raspberrypi.org).
> +
> +# Status
> +
> +This firmware, that has been validated to compile against the current
> +[edk2](https://github.com/tianocore/edk2)/[edk2-platforms](https://github.com/tianocore/edk2-platforms),
> +should be able to boot Linux (SUSE, Ubuntu), NetBSD, FreeBSD as well as Windows 10 ARM64
> +(full GUI version).
> +
> +It also provides support for ATF ([Arm Trusted Platform](https://github.com/ARM-software/arm-trusted-firmware)).
> +
> +HDMI and the mini-UART serial port can be used for output devices, with mirrored output.
> +USB keyboards and the mini-UART serial port can be used as input.
> +
> +The boot order is currently hardcoded, first to the USB ports and then to the uSD card.
> +If there no bootable media media is found, the UEFI Shell is launched.
> +<kbd>Esc</kbd> enters platform setup. <kbd>F1</kbd> boots the UEFI Shell.
> +
> +# Building
> +
> +(These instructions were validated against the latest edk2 / edk2-platforms /
> +edk2-non-osi as of 2019.01.27, on a Debian 9.6 x64 system).
> +
> +You may need to install the relevant compilation tools. Especially you should have the
> +ACPI Source Language (ASL) compiler, `nasm` as well as a native compiler installed.

nasm? The x86 assembler?

> +On a Debian system, you can get these prerequisites installed with:
> +```
> +sudo apt-get install build-essential acpica-tools nasm uuid-dev
> +```
> +
> +**IMPORTANT:** We recommend the use of the Linaro GCC for compilation instead of
> +your system's native ARM64 GCC cross compiler.

This sounds like something written in the days of GCC 4.8. I doubt it
has any relevance today.

Also, and this applies both above and below: I am trying very hard to
get rid of (mostly unnecessary) platform-specific build instructions.
The top-level Readme.md in this repository contains basic build
instructions. I would much prefer if you can refer to that instead and
drop everything after the # Building header above...

> +
> +You can then build the firmware as follows:
> +
> +* Standalone instructions
> +
> +```
> +mkdir ~/workspace
> +cd ~/workspace
> +git clone https://github.com/tianocore/edk2.git
> +# The following is only needed once, after you cloned edk2
> +make -C edk2/BaseTools
> +git clone https://github.com/tianocore/edk2-platforms.git
> +git clone https://github.com/tianocore/edk2-non-osi.git
> +wget https://releases.linaro.org/components/toolchain/binaries/7.4-2019.02/aarch64-linux-gnu/gcc-linaro-7.4.1-2019.02-x86_64_aarch64-linux-gnu.tar.xz
> +tar -xJvf gcc-linaro-7.4.1-2019.02-x86_64_aarch64-linux-gnu.tar.xz
> +# If you have multiple AARCH64 toolchains, make sure the above one comes first in your path
> +export PATH=$PWD/gcc-linaro-7.4.1-2019.02-x86_64_aarch64-linux-gnu/bin:$PATH
> +export GCC5_AARCH64_PREFIX=aarch64-linux-gnu-
> +export WORKSPACE=$PWD
> +export PACKAGES_PATH=$WORKSPACE/edk2:$WORKSPACE/edk2-platforms:$WORKSPACE/edk2-non-osi
> +. edk2/edksetup.sh

...down to here.
(I would certainly not object if you felt the need to improve on the
contents of the top-level Readme.md. For example with the explicit
prerequisite installation steps, rather than the brief list provided
under the Prerequisites section currently on that page.)

> +build -a AARCH64 -t GCC5 -p edk2-platforms/Platform/Raspberry/Pi3/RPi3.dsc -DBUILD_EPOCH=`date +%s` -b RELEASE
> +```
> +

The below _is_ platform-specific, so clearly I have no issue with
it. Not sure that needed poinging out, but...
And the above line points out the location of the .dsc, so no
objection there.

> +# Booting the firmware
> +
> +1. Format a uSD card as FAT32
> +2. Copy the generated `RPI_EFI.fd` firmware onto the partition
> +3. Download and copy the following files from https://github.com/raspberrypi/firmware/tree/master/boot
> +  - `bootcode.bin`
> +  - `fixup.dat`
> +  - `start.elf`
> +4. Create a `config.txt` with the following content:
> +  ```
> +  arm_control=0x200
> +  enable_uart=1
> +  armstub=RPI_EFI.fd
> +  disable_commandline_tags=1
> +  ```
> +5. Insert the uSD card and power up the Pi.
> +
> +Note that if you have a model 3+ or a model 3 where you enabled USB boot through OTP
> +(see [here](https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md))
> +you may also be able to boot from a FAT32 USB driver rather than uSD.
> +
> +# Notes
> +
> +## ARM Trusted Firmware (ATF)
> +
> +The ATF binaries being used were compiled from the ATF mainline.

With additional modifications?

> +
> +For more details on the ATF compilation, see the [README](./Binary/README.md) in the `Binary/` directory.

This directory no longer exists.
You could point at the full URL in the edk2-non-osi repository.

> +
> +## Custom Device Tree
> +
> +The default Device Tree included in the firmware is the one for a Raspberry Pi 3 Model B (not B+).
> +If you want to use a different Device Tree, to boot a Pi 3 Model B+ for instance (for which a
> +DTB is also provided under `DeviceTree/`), you should copy the relevant `.dtb` into the root of
> +the SD or USB, and then edit your `config.txt` so that it looks like:
> +
> +```
> +(...)
> +disable_commandline_tags=2
> +device_tree_address=0x10000
> +device_tree_end=0x20000
> +device_tree=bcm2710-rpi-3-b-plus.dtb
> +```
> +
> +Note: the address range **must** be `[0x10000:0x20000]`.
> +`dtoverlay` and `dtparam` parameters are also supported **when** providing a Device Tree`.
> +
> +## Custom `bootargs`
> +
> +This firmware will honor the command line passed by the GPU via `cmdline.txt`.
> +
> +Note, that the ultimate contents of `/chosen/bootargs` are a combination of several pieces:
> +- Original `/chosen/bootargs` if using the internal DTB. Seems to be completely discarded by GPU when booting with a custom device tree.
> +- GPU-passed hardware configuration. This one is always present.
> +- Additional boot options passed via `cmdline.txt`.
> +
> +# Tested Platforms

I won't press the issue, but I would prefer for the operating system
installation instructions not to be included.
If you do want it in this repo, please break it out into a separate
Readme.md, which you can link to from here.
Basically, skp straight to "Limitations" from here.

> +
> +## Ubuntu
> +
> +[Ubuntu 18.04 LTS](http://releases.ubuntu.com/18.04/) has been tested and confirmed to work,
> +on a Raspberry 3 Model B, including the installation process. Note however that network
> +installation and networking may not work on the Model B+, due to the `lan78xx` Linux driver
> +still requiring some support.
> +
> +Below are the steps you can follow to install Ubuntu LTS onto SD/USB:
> +* Download the latest Ubuntu LTS ARM64 [`mini.iso`](http://ports.ubuntu.com/ubuntu-ports/dists/bionic/main/installer-arm64/current/images/netboot/mini.iso).
> +* Partition the media as MBR and create a ~200 MB FAT32 partition on it with MBR type `0x0c`.
> +  Note: Do not be tempted to use GPT partition scheme or `0xef` (EFI System Partition) for the
> +  type, as none of these are supported by the Raspberry Pi's internal boot rom.
> +* Extract the full content of the ISO onto the partition you created.
> +* Also extract the GRUB EFI bootloader `bootaa64.efi` from `/boot/grub/efi.img` to `/boot/grub/`.
> +  Note: Do not be tempted to copy this file to another directory (such as `/efi/boot/`) as GRUB looks for its
> +  modules and configuration data in the same directory as the EFI loader and also, the installation
> +  process will create a `bootaa64.efi` into `/efi/boot/`.
> +* If needed, copy the UEFI firmware files (`RPI_EFI.fd`, `bootcode.bin`, `fixup.dat` and `start.elf`)
> +  onto the FAT partition.
> +* Boot the pi and let it go into the UEFI shell.
> +* Navigate to `fs0:` then `/boot/grub/` and launch the GRUB efi loader.
> +* Follow the Ubuntu installation process.
> +
> +Note: Because Ubuntu operates in quiet mode by default (no boot messages), you may think the system is frozen
> +on first reboot after installation. However, if you wait long enough you **will** get to a login prompt.
> +
> +Once Linux is running, if desired, you can disable quiet boot, as well as force the display
> +of the GRUB selector, by editing `/etc/default/grub` and changing:
> +* `GRUB_TIMEOUT_STYLE=hidden` &rarr; `GRUB_TIMEOUT_STYLE=menu`
> +* `GRUB_CMDLINE_LINUX_DEFAULT="splash quiet"` &rarr; `GRUB_CMDLINE_LINUX_DEFAULT=""`
> +
> +Then, to have your changes applied run `update-grub` and reboot.
> +
> +## Other Linux distributions
> +
> +* Debian ARM64 does not currently work, most likely due to missing required module support
> +  in its kernel. However its installation process works, so it may be possible to get it
> +  running with a custom kernel.
> +
> +* OpenSUSE Leap 42.3 has been reported to work on Raspberry 3 Model B.
> +
> +* Other ARM64 Linux releases, that support UEFI boot and have the required hardware support
> +  for Pi hardware are expected to run, though their installation process might require some
> +  cajoling.
> +
> +## Windows
> +
> +Windows 10 1809 for ARM64 (build 17763) has been tested and confirmed to work (after replacing
> +`C:\Windows\System32\Drivers\WppRecorder.sys` with an older version, since the one from 1809
> +appears to be buggy across all archs, and results in a similar BSOD when trying to run Windows
> +To Go on x64 with native drivers for instance).
> +
> +Windows 10 1803 for ARM64 and earlier do not work due to the presence of a hardware ASSERT check
> +in the Windows kernel, that was removed in later versions.
> +
> +You probably want to look at https://www.worproject.ml/ as well as the
> +[Windows thread in the original RaspberryPiPkg](https://github.com/andreiw/RaspberryPiPkg/issues/12)
> +for installation details.
> +
> +## Other platforms
> +
> +Details you may need to run other platforms, including FreeBSD, is provided in the
> +[Readme from the original RaspberryPiPkg](https://github.com/andreiw/RaspberryPiPkg).
> +
> +# Limitations
> +
> +## HDMI
> +
> +The UEFI HDMI video support relies on the VC (that's the GPU)
> +firmware to correctly detect and configure the attached screen.
> +Some screens are slow, and this detection may not occur fast
> +enough. Finally, you may wish to be able to boot your Pi
> +headless, yet be able to attach a display to it later for
> +debugging.
> +
> +To accommodate these issues, the following extra lines
> +are recommended for your `config.txt`:
> +- `hdmi_force_hotplug=1` to allow plugging in video after system is booted.
> +- `hdmi_group=1` and `hdmi_mode=4` to force a specific mode, both to accommodate
> +   late-plugged screens or buggy/slow screens. See [official documentation](https://www.raspberrypi.org/documentation/configuration/config-txt/video.md)
> +   to make sense of these parameters (example above sets up 720p 60Hz).
> +
> +## NVRAM
> +
> +The Raspberry Pi has no NVRAM.
> +
> +NVRAM is emulated, with the non-volatile store backed by the UEFI image itself. This means
> +that any changes made in UEFI proper will be persisted, but changes made in HLOS will not.
> +It would be nice to implement ATF-assisted warm reboot, to allow persisting HLOS
> +NVRAM changes.
> +
> +## RTC
> +
> +The Rasberry Pi has no RTC.
> +
> +`RtcEpochSeconds` NVRAM variable is used to store the boot time
> +This should allow you to set whatever date/time you
> +want using the Shell date and time commands. While in UEFI
> +or HLOS, the time will tick forward. `RtcEpochSeconds`
> +is not updated on reboots.
> +
> +## uSD
> +
> +UEFI supports both the Arasan SDHCI and the Broadcom SDHost controllers to access the uSD slot.
> +You can use either. The other controller gets routed to the SDIO card. The choice made will
> +impact ACPI OSes booted (e.g. Windows 10). Arasan, being an SDIO controller, is usually used
> +with the WiFi adapter where available. SDHost cannot be used with SDIO. In UEFI setup screen:
> +- go to `Device Manager`
> +- go to `Raspberry Pi Configuration`
> +- go to `Chipset`
> +- configure `Boot uSD Routing`
> +
> +Known issues:
> +- Arasan HS/4bit support is missing.
> +- No 8 bit mode support for (e)MMC (irrelevant for the Pi 3).
> +- Hacky (e)MMC support (no HS).
> +- No card removal/replacement detection, tons of timeouts and slow down during boot without an uSD card present.
> +
> +## USB
> +
> +- USB1 BBB mass storage devices untested (USB2 and USB3 devices are fine).
> +- USB1 CBI mass storage devices don't work (e.g. HP FD-05PUB floppy).
> +
> +## ACPI
> +
> +ACPI should match the MS-IoT one. Both Arasan and SDHost SD controllers are exposed.

It would be good if you could add a comment here about the limitations
with regards to proper ACPI description and its unusability for Linux.

> +
> +## Missing Functionality
> +
> +- Network booting via onboard NIC.
> +- Ability to switch UART use to PL011.
> diff --git a/Readme.md b/Readme.md
> index 384b1d3c5e2b..d82b7581ba6d 100644
> --- a/Readme.md
> +++ b/Readme.md
> @@ -217,6 +217,9 @@ they will be documented with the platform.
>  ## Marvell
>  * [Armada 70x0](Platform/Marvell/Armada)
>  
> +## Raspberry

Raspberry Pi

/
    Leif

> +* [Pi 3](Platform/Raspberry/Pi3)
> +
>  ## Socionext
>  * [SynQuacer](Platform/Socionext/DeveloperBox)
>  
> -- 
> 2.17.0.windows.1
>