On 4/4/20 11:57 AM, François Ozog wrote:
> Hi,
>
> I instrumented boot on my Ubuntu 18.04 server right after systemd startup
> and caught an access to:
> /sys/firmware/efi/efivars/LoaderDevicePartUUID-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f
Jeremy's patch 06f7d4a1618d ("efibc: Add EFI Bootloader Control module")
introduced the variable though this change seems to be unrelated to the
commit message. See efibc_set_variable() in drivers/firmware/efi/efibc.c.
@Jeremy, Ard
Why is this variable written when CONFIG_EFI_BOOTLOADER_CONTROL=y? It
seems not be related to the description of the customizing setting.
According to the UEFI spec the SetVariable() service is optional at
run-time.
I have started work on implementing variable services at run-time in
U-Boot. See https://lists.denx.de/pipermail/u-boot/2020-March/404441.html.
Best regards
Heinrich
>
> This led to:
> https://systemd.io/DISCOVERABLE_PARTITIONS/
> And then:
> https://systemd.io/BOOT_LOADER_INTERFACE/
> https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT/
>
> My server is configured with Grub to boot (grub and kernel on a HD, root FS
> of NVME as grub do not have nvme driver for my card) but the udev is still
> checking those systemd-boot variables.
>
> From a boot loader perspective, we have the following EFI applications:
> - Grub2
> - EFIBootGuard (used by CIP)
> - Systemd-boot (used by ?)
>
> Regardless of the loader, I assume we need to ensure whatever option is
> selected by solution builders, they can implement it with our U-Boot
> reference implementation of UEFI.
>
> The Systemd boot-bless seems of high interest for rolling back UEFI update
> capsules of firmware...
>
> I'd be happy to get some feed back on :
> - the systemd-boot technology
> - whether we need to implement the above specs in our UEFI implementation
> - whether this has an influence on EBBR
>
> Cheers
>
> FF
>
> PS: other references
> https://manpages.debian.org/testing/systemd/systemd-boot.7.en.html
> https://manpages.debian.org/testing/systemd/systemd-bless-boot.service.8.en.html
> http://man7.org/linux/man-pages/man1/bootctl.1.html
>
>
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