fmdefrancesco at gmail.com
Thu Sep 23 03:22:24 EDT 2021
On Thu, 23 Sep 2021, 09:11 FMDF, <fmdefrancesco at gmail.com> wrote:
> On Wed, 22 Sep 2021, 08:22 Ruben Safir, <ruben at mrbrklyn.com> wrote:
>> What is this for?
>> efivarfs on /sys/firmware/efi/efivars type efivarfs
>> why would the OS need to know anything about the UEFI
>> boot loader once it is up and running?
> I think you are still making confusion: UEFI bootloaders and UEFI are two
> different entities.
> UEFI bootloaders (like Grub2) serve the purpose to locate, pass kernel
> options and platform information to the kernel that themselves are going
> to boot.
> Instead the UEFI is an interface between the running OS and the platform
> UEFI defines two types of services: boot services and runtime services.
> After booting is done, via UEFI boot services and eventually UEFI
> bootloaders, the OS does not need anymore the bootloader and the UEFI boot
> Instead the OS needs UEFI runtime services to talk to the platform
> firmware. For example, if OS cannot talk to the platform via UEFI, it
> cannot even shutdown the system (obviously there is much more than simply
> shutting down). How can an OS know that you've attached a plug and play
> device if it cannot talk to the platform firmware?
For sake of completeness and for better understanding that OS need UEFI,
but not necessarily EFI bootloaders, please read the following document:
Linux can boot without bootloaders, but it still needs to use UEFI at
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