Hi Mark,
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Open questions: Looking at the EFI spec, I can't find a documented way of notifying the OS that the storage is volatile. I would like to send a hint to the OS about that and I was thinking of adding a configuration table with the filename, which U-Boot expects to be on the ESP. Alternatively we could add a device path which would be a bit harder to parse from the userspace application, but safer in case multiple ESPs are present.
Should there be a way for the OS to opt-in to this new behaviour?
The feature itself is in a Kconfig option. If we agree on a way to notify the OS that the variable storage is in RAM and hence volatile, the OS is free to ignore it I guess
Since I am not too familiar with how BSDs treat and expose config tables, we could instead add a RO efi variable with identical semantics, which would be easier to read from userspace.
There is an EFIIOC_GET_TABLE ioctl that allows retreiving a table by GUID.
Ah thanks. I am leaning towards an EFI variable now to signal the OS
[...]
/Ilias