[edk2-platforms: PATCH v3 1/1] Platform/RPi3: Add Debian 10 installation in Systems.md

["Pete Batard" <pete@akeo.ie>]

This documents the installation of vanilla Debian 10.0 ARM64 (netinst),
which we validated for both Model B and Model B+.
Also fix an erroneous reference in an RPi3.fdf comment.

Signed-off-by: Pete Batard <pete@akeo.ie>
---
 Platform/RaspberryPi/RPi3/RPi3.fdf   |   2 +-
 Platform/RaspberryPi/RPi3/Readme.md  |   4 +-
 Platform/RaspberryPi/RPi3/Systems.md | 127 +++++++++++++++++++-
 3 files changed, 126 insertions(+), 7 deletions(-)

diff --git a/Platform/RaspberryPi/RPi3/RPi3.fdf b/Platform/RaspberryPi/RPi3/RPi3.fdf
index c7c3f7a2ab8c..c62d649834c7 100644
--- a/Platform/RaspberryPi/RPi3/RPi3.fdf
+++ b/Platform/RaspberryPi/RPi3/RPi3.fdf
@@ -300,7 +300,7 @@ [FV.FvMain]
   INF Platform/RaspberryPi/$(PLATFORM_NAME)/Drivers/LogoDxe/LogoDxe.inf
 
   #
-  # FDT (GUID matches mRaspberryPiFfsFileGuid in RaspberryPiPlatformDxe)
+  # FDT (GUID matches gRaspberryPiFdtFileGuid in FdtDxe)
   #
   FILE FREEFORM = DF5DA223-1D27-47C3-8D1B-9A41B55A18BC {
     SECTION RAW = Platform/RaspberryPi/$(PLATFORM_NAME)/DeviceTree/bcm2710-rpi-3-b.dtb
diff --git a/Platform/RaspberryPi/RPi3/Readme.md b/Platform/RaspberryPi/RPi3/Readme.md
index 624f3a8d287a..797da1bab4a9 100644
--- a/Platform/RaspberryPi/RPi3/Readme.md
+++ b/Platform/RaspberryPi/RPi3/Readme.md
@@ -18,8 +18,8 @@ Raspberry Pi is a trademark of the [Raspberry Pi Foundation](http://www.raspberr
 
 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).
+should be able to boot Linux (Debian, Ubuntu, SUSE), 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)).
 
diff --git a/Platform/RaspberryPi/RPi3/Systems.md b/Platform/RaspberryPi/RPi3/Systems.md
index f6410eb25f0d..3a313c29cbdc 100644
--- a/Platform/RaspberryPi/RPi3/Systems.md
+++ b/Platform/RaspberryPi/RPi3/Systems.md
@@ -1,5 +1,128 @@
 # Tested Operating Systems
 
+## Debian
+
+[Debian 10](https://cdimage.debian.org/debian-cd/current/arm64/iso-cd/) netinst has been
+tested and confirmed to work, both on the Model B and Model B+, including installation in
+either wired or wireless mode.
+
+Below are steps you can follow to install Debian 10 onto an SD card:
+* Partition the media as MBR and create a ~300 MB partition on it with MBR type `0x0e`.
+  __Note:__ Make sure that the partition scheme is MBR (not GPT) and the type `0x0e` (not
+  `0xef` for instance), as the on-CPU Broadcom bootloader supports neither the GPT scheme
+  nor the ESP MBR type.
+* Set the partition as active/bootable. This is needed as the Debian partition manager can
+  not detect it as ESP otherwise, which we need for GRUB installation. If using `fdisk` on
+  Linux, you can use the `a` command to set a partition as active. On Windows, you can use
+  `diskpart` and then type `active` after selecting the relevant disk and partition.
+* Format the partition as FAT. Here you should make sure that you use FAT16 over FAT32 else
+  the Debian partition manager may not automatically detect the partition as ESP. If you
+  are using Windows `diskpart` then `format fs=fat quick` will format a drive to FAT16. On
+  Linux, the equivalent command would be `mkfs.vfat -F 16 /dev/<your_device>`. As long as
+  the partition is smaller than 2 GB, the use of FAT16 over FAT32 should not be a problem.
+  Note that it is also possible to use FAT32, but you will probably have to invoke `fdisk`
+  before rebooting, as shown in the _Additional Notes_ below, to reset the partition type.
+* Copy the UEFI firmware files (`RPI_EFI.fd`, `bootcode.bin`, `fixup.dat` and `start.elf`)
+  as well as an appropriate `config.txt` onto the FAT partition. If needed you can download
+  the non UEFI binary files from https://github.com/raspberrypi/firmware/tree/master/boot.
+* (Optional) If you plan to install through WiFi, you will need to download relevant
+  non-free  WLAN firmware binaries from your WLAN interface (`brcmfmac43430-sdio.txt` and
+  `brcmfmac43430-sdio.bin` for a Raspberry Pi 3 Model B, `brcmfmac43455-sdio.txt` and
+  `brcmfmac43455-sdio.bin` for a Raspberry Pi 3 Model B+). You may also want to obtain the
+  relevant `.clm_blob` (`brcmfmac43430-sdio.clm_blob` or `brcmfmac43455-sdio.clm_blob`),
+  though wireless networking should work even if you do not provide these files. Copy these
+  files either at the root of your FAT partition or into a `firmware/` directory there.
+* Download the latest `debian-##.#.#-arm64-netinst.iso` from
+  https://cdimage.debian.org/debian-cd/current/arm64/iso-cd/
+* Extract the full content of the ISO onto the FAT partition you created.
+* Insert the media and power up the Raspberry Pi device.
+* On the GRUB menu select `Install` and let the Debian Installer process start.
+  __Note:__ In case anything goes wrong during the install process, you can use
+  <kbd>Alt</kbd>-<kbd>F4</kbd> to check the installation log.
+* Select your Language, Country and Keyboard and let the installer proceed until it reports
+  that `No Common CD-ROM drive was detected.`
+* On `Load CD-ROM drivers from removable media` select `No`.
+* On `Manually select a CD-ROM module and device` select `Yes`.
+* On `Module needed for accessing the CD-ROM` select `none`.
+* On `Device file for accessing the CD-ROM` type the following exactly:
+  ```
+  -t vfat -o rw /dev/mmcblk0p1
+  ```
+* (Optional) If you have copied the non-free WLAN firmware binaries, and plan to install
+  through wireless, you can let the installer select the firmware files. Please be mindful
+  that you may be asked multiple times as there are multiple files to provide.
+* If requested by the installer, set up your network by choosing the network interface you
+  want to use for installation and (optionally) your access point and credentials.
+* Go through the hostname, user/password set up and customize those as you see fit.
+* Let the installer continue until you get to the `Partition disks` screen. There, for
+  `Partitioning method` select `Manual`. You __should__ see something like this:
+  ```
+  MMC/SD card #1 (mmcblk0) - 16.0 GB SD 2WCGO
+       #1  primary  314.6 MB  B  K  ESP
+           pri/log                  FREE SPACE
+  ```
+  In other words, the partition manager should already detect your existing partition as
+  `ESP`, with the `B` (bootable) and `K` (keep data) flags. If that is not the case, (e.g.
+  if it says `fat16` or `fat32` instead of `ESP`) then it probably means you either didn't
+  format the partition to FAT16 or you forgot to set the bootable flag. In that case,
+  please refer to the _Additional Notes_ below.
+* Select `FREE SPACE` &rarr; `Create a new partition` and create a `1 GB` primary `swap`
+  partition.
+* Select `FREE SPACE` &rarr; `Create a new partition` and allocate the rest to a primary
+ `ext4` root partition (mountpoint = `/`)
+* After doing the above, your partition report should look like this:
+  ```
+  MMC/SD card #1 (mmcblk0) - 16.0 GB SD 2WCGO
+       #1  primary  314.6 MB  B  K  ESP
+       #2  primary    1.0 GB     f  swap    swap
+       #3  primary   14.7 GB     f  ext4    /
+  ```
+* Select `Finish partitioning and write changes to disk` and then `Yes` and let the
+  installer continue with the base system installation.
+* After a while, the installer should produce a message that states:
+  ```
+  [!!] Configure the package manager
+
+  apt-configuration problem
+  An attempt to configure apt to install additional packages from the CD failed.
+  ```
+  This is a __benign__ message that you can safely ignore by selecting `Continue` (The
+  reason it is benign is we are running a net install and won't need to access the "CD-ROM"
+  files post install).
+* Once you have dimissed the message above, pick the mirror closest to your geographical
+  location and let the installer proceed with some more software installation.
+* Finally, at the `Software selection` screen, choose any additional software package you
+  wish to install. `Debian desktop environment` should work out of the box if you choose to
+  install it.
+* Let the process finalize the software and GRUB bootloader installation and, provided you
+  didn't run into the partition manager issue described above (installation partition not
+  seen as `ESP`) you can reboot your machine when prompted, which, once completed, should
+  bring you to your newly installed Debian environment.
+
+### Additional Notes for Debian
+
+The reason we use `-t vfat -o rw /dev/mmcblk0p1` for the source media (i.e. "CD-ROM" device)
+is because, whereas the first partition on the SD card is indeed `/dev/mmcblk0p1`, we also
+need to provide additional parameters for the `mount` command that the installer invokes
+behind the scenes. For instance, if we don't use `-t vfat`, then ISO-9660 is forced as the
+file system, and if we don't use `-o rw` then the partition will be mounted as read-only
+which then prevents the same partition from being remounted when locating the non-free
+firmware files or when setting up `/efi/boot`.
+
+With regards to fixing the partitioning if you don't see `B  K  ESP` when entering the
+partition manager, what you need to do is:
+* Before you create the additional partitions, select the first partition and change its
+  type to `ESP`. Note however that doing this changes the type of the partition to `0xef`
+  which is precisely what we're trying to avoid by having the partition manager already
+  detect it as ESP, as type `0xef` is __unbootable__ by the Broadcom CPU.
+* To fix this then, before you choose `Continue` on the `Installation complete` prompt you
+  should open a new console with <kbd>Alt</kbd>-<kbd>F2</kbd> and type:
+  ```
+  chroot /target fdisk /dev/mmcblk0
+  ```
+  Then press <kbd>t</kbd>, <kbd>1</kbd>, <kbd>e</kbd> <kbd>w</kbd>, to reset the partition
+  to type `0x0e` (FAT16 LBA).
+
 ## Ubuntu
 
 [Ubuntu 18.04 LTS](http://releases.ubuntu.com/18.04/) has been tested and confirmed to work,
@@ -35,10 +158,6 @@ 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
-- 
2.21.0.windows.1