2019-09-23 - Beta test for network boot

Fixed duplicated net-retries in bootconf.txt from 2019-09-22 and added
padding back.

firmware/raspberry_pi4_network_boot_beta.md

@@ -0,0 +1,130 @@
+# Raspberry Pi4 network boot (BETA)
+The page describes how to install and configure network boot for the Raspberry Pi4 Model B.
+
+**This is an early beta test and has only been tested on a small number of networks. Check with your network administrator before enabling network boot.**
+
+This documentation will be merged into the main bootloader documents after the beta test is complete.
+
+## Known issue
+* For unknown reasons the brcmfmac wifi is not initialised in netowrk boot mode.
+* Linux 5.3 kernel seems to poll SDHCI SD ever 10 seconds printing warnings to dmesg
+* A timeout reading start4.elf causes start.elf to be loaded, start.elf should only be loaded if start4.elf does not exist.
+
+## Server configuration
+Network boot requires a TFTP and NFS server to be configured.  See [Network boot server tutorial](https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/net_tutorial.md)
+
+Additional notes:-
+* The VideoCore firmware (start4.elf) must be updated to the latest rpi-update version in order to get the Pi4 network drivers.
+* The MAC address on the Pi4 is programmed at manufacture and is not derived from the serial number.
+
+```
+# mac adddress (ip addr) - it should start with DC:A6:32
+ip addr | grep ether | head -n1 | awk '{print $2}' | tr [a-z] [A-Z]
+
+# serial number
+vcgencmd otp_dump | grep 28: | sed s/.*://g
+```
+
+## Installation - Updating firmware and bootloader
+```
+# Install the rpi-eeprom update package
+sudo apt update
+sudo apt upgrade
+sudo apt install rpi-eeprom
+
+# Get the latest VideoCore firmware which includes the Pi4 network driver in start4.elf
+sudo rpi-update
+
+# (Optional) Update rpi-eeprom-update to automatically get updates / bug fixes.
+sudo echo FIRMWARE_RELEASE_STATUS="beta" > /etc/default/rpi-eeprom-update
+```
+
+### Configuration - Enable network boot
+Network boot is not enabled by default in the bootloader. To enable it the bootloader configuration file must be edited.
+```
+# Extract the configuration file
+cp /lib/firmware/raspberrypi/beta/pieeprom-2019-09-23.bin pieeprom.bin
+rpi-eeprom-config pieeprom.bin > bootconf.txt
+
+# Enable network boot
+# change boot_order from 0x1 (sd-boot) to 
+BOOT_ORDER=0x21
+# sd-boot then failover to network boot
+
+# If you have a UART cable then setting BOOT_UART=1 will help debug network boot issues
+BOOT_UART=1
+
+# Apply the configuration change to the EEPROM image file
+rpi-eeprom-config --out pieeprom-netboot.bin --config bootconf.txt pieeprom.bin
+```
+
+### Update the bootloader EEPROM
+```
+# Flash the bootloader EEPROM with network boot enabled
+# Run 'rpi-eeprom-update -h' for more information
+sudo rpi-eeprom-update -d -f ./pieeprom-netboot.bin
+sudo reboot
+```
+
+## TFTP prefix
+As with the Pi3 bootloader the presence of /serial_number/start.elf is used to detect
+whether the serial number should be used as the directory prefix for TFTP requests.
+
+N.B. A future update might additionally check for start4.elf as well as start.elf
+in order to have a Pi4 specific TFTP root. The current assumption is that the TFTP
+root directory has copied as-is from a Raspbian Buster image file.
+
+The bootloader loads start4.elf in preference to start.elf so it's possible to
+just have an empty start.elf file if you only want to have Pi4 firmware in the TFTP
+root directory.
+
+## Bootloader configuration
+
+### BOOT_ORDER
+The BOOT_ORDER setting allows flexible configuration for the priority of different
+bootmodes. It is represented as 32bit unsigned integer where each nibble represents
+a bootmode. The bootmodes are attempted in LSB to MSB order.  
+
+E.g. 0x21 means try SD first followed by network boot then stop. Where as
+0x2 would mean try network boot and then stop without trying to boot from
+the sd-card.
+
+The retry counters are reset when switching to the next boot mode.
+
+BOOT_ORDER fields  
+* 0x0 - NONE (stop with error pattern)  
+* 0x1 - SD CARD  
+* 0x2 - NETWORK  
+
+Default: 0x00000001 (with 3 SD boot retries to match the current bootloader behaviour)  
+
+### SD_BOOT_MAX_RETRIES
+Specify the maximum number of times that the bootloader will retry booting from the sd-card.  
+-1 means infinite retries  
+Default: 0  
+
+### NET_BOOT_MAX_RETRIES
+Specify the maximum number of times that the bootloader will retry network boot.  
+-1 means infinite retries  
+Default: 0  
+
+### DHCP_TIMEOUT
+The timeout in milliseconds for the entire DHCP sequence before failing the current iteration.  
+Default: 45000  
+Minimum: 5000  
+
+### DHCP_REQ_TIMEOUT
+The timeout in milliseconds before retrying DHCP DISCOVER or DHCP REQ.  
+Default: 4000  
+Minimum: 500  
+
+### TFTP_TIMEOUT
+The timeout in milliseconds for an individual file download via TFTP.  
+Default: 15000  
+Minimum: 5000  
+
+### TFTP_IP
+Optional dotted decimal ip address (e.g. 192.169.1.99) for the TFTP server which overrides the server-ip from the DHCP request.  
+This maybe useful on home networks because tftpd-hpa can be used instead of dnsmasq where broadband router is the DHCP server.
+Default: ""  
+

firmware/release-notes.md

@@ -1,5 +1,9 @@
 # Raspberry Pi4 bootloader EEPROM release notes
 
+## 2019-09-23 - Git c67e8bb3 (BETA)
+   * Add support for network boot
+   * Configurable ordering for boot modes (BOOT_ORDER and SD/NET_BOOT retries)
+
 ## 2019-09-10 - Git f626c772
    * Configure ethernet RGMII pins at power on. This is a minor change which
      which may improve reliability of ethernet for some users.