Open RomanValov opened 3 years ago
lurch
commented
3 years ago My goal is to prevent to boot from network for flashed devices.
If you changed the boot-order to BOOT_ORDER=0xf21 would it attempt to boot from eMMC, but then fail (because the eMMC is empty) and drop through to network-booting? And if the network-boot then flashed an image onto the eMMC and rebooted, I guess it'd then boot from eMMC for all subsequent boots?
timg236
commented
3 years ago Zero byte start.elf / start4.elf files are fine and I see no reason to change remove support for that.
It might be reasonable to add something to the EEPROM_CONFIG to disable the fallback to the non-prefixed directory. The default would be the same as Pi3 which has the fallback.
RomanValov
commented
3 years ago My goal is to prevent to boot from network for flashed devices.
If you changed the boot-order to
BOOT_ORDER=0xf21would it attempt to boot from eMMC, but then fail (because the eMMC is empty) and drop through to network-booting? And if the network-boot then flashed an image onto the eMMC and rebooted, I guess it'd then boot from eMMC for all subsequent boots?
Your proposal may work in some scenarios. However in my case in some scenarios I have to periodically switch between network and eMMC boots. I.e. testing firmwares from the CI/CD pipeline: boot from network - flash - boot from eMMC - test - revert to network boot. Making eMMC boot a priority will require dealing with eMMC which is not always as convenient. I.e. in case of broken image I have to connect the board with USB cable and run usbboot. I consider it to be less convenient than wipe directory on the server (maybe automated) and power cycle the board.
RomanValov
commented
3 years ago Zero byte start.elf / start4.elf files are fine and I see no reason to change remove support for that.
It might be reasonable to add something to the EEPROM_CONFIG to disable the fallback to the non-prefixed directory. The default would be the same as Pi3 which has the fallback.
Thank you for the clarification.
As of option, just a note that in my scenario fallback to non-prefixed directory should be disabled only if prefixed directory exists but enabled otherwise.
lurch
commented
3 years ago Ahhh, so what you actually want is "selectively prevent boot from network for flashed devices, with the network still having the ability to override that choice" ? :wink:
timg236
commented
3 years ago TFTP doesn't support directory existence checks. The firmware would failover to the non-prefix dir or if specified only request firmware from the prefix dir. For customising the BOOT_ORDER at runtime you might be better of using conditional GPIO filters.
RomanValov
commented
3 years ago Ahhh, so what you actually want is "selectively prevent boot from network for flashed devices, with the network still having the ability to override that choice" ? wink
Yeah, exactly
RomanValov
commented
3 years ago TFTP doesn't support directory existence checks. The firmware would failover to the non-prefix dir or if specified only request firmware from the prefix dir. For customising the BOOT_ORDER at runtime you might be better of using conditional GPIO filters.
Unfortunately using GPIO filters completely break my idea of fully automated setup and would require human interaction to alter GPIO configuration (I admit you meant using something like jumpers).
timg236
commented
3 years ago Tweaking the TFTP rules to fit a custom flashing process seems like the wrong approach. Since the server will see the MAC address in the DHCP request I think you can do this all server side.
Board: Raspberry Pi Compute Module 4 Rev 1.0
I'm developing an automated network flashing daemon for RPi boards based on PXE/TFTP server. My boards are configured with
BOOT_ORDER=0xf12andTFTP_PREFIX=2, so network boot is preferred and tftp prefix based on MAC-address is preferred.Flashing workflow is following:
start.elfandstart4.elfEverything is working fine. However I'm relying on kind of undocumented behavior of boot from prefixed directory. My goal is to prevent to boot from network for flashed devices.
If prefixed directory didn't contain any
start4.elf/start.elffiles the bootloader fallbacks to network boot from non-prefixed directory and that would break the workflow.If prefixed directory contained proper
start4.elf/start.elffiles the bootloader continues network boot from prefixed directory and that would break the workflow.I'm afraid relying on zero-sized
start4.elf/start.elfas a method to skip network boot could be broken one day. So I would ask either to provide a guarantee for the behavior (i.e. document it), or maybe provide some kind of more clean and straight-forward way to skip network boot, i.e. putting kind of skip-marker-file in a prefix dir to prevent fallback to non-prefixed dir and skip network boot method.Sorry if there is already a method to do this that I have missed.
Network boot (please complete the following information):
Here is a log of boot from prefixed directory:
Here is a log of boot from non-prefixed directory: