If after booting Linux a directory "efi" is present in /sys/firmware, the system booted EFI. If the directory is not present, it booted legacy BIOS.
I will leave diagnosis of what's going on with your computer and why to its administrator. On Tue, Sep 12, 2023 at 11:41 AM Moses Gold <[email protected]> wrote: > Thought I might have UEFI malware after trying to install an old version > of Windows. Looks like sector one of the drive is just part of the GPT > partition table scheme and not an EFI partition itself. Sector 2 looks like > the beginning of the BIOS boot partition with the grub GUID signature, > though the partitioning software (gdisk, and gparted) state that partition > 1 starts at sector 2048. The partition at sector 2048 has an EFI directory > structure, and includes the grubx64.efi file. I was looking at grub with > interest because when I went to reset my UEFI firmware (windows key plus > "B" on power up), I initially booted into a grub command prompt rather than > a UEFI menu. I was thinking that maybe some malware had loaded grub in > place of the regular UEFI firmware (could be that the firmware uses grub > legitimately during the firmware reset?). Anyway, I was able to load > windows 10 from this grub command line, and ran a BIOS update app > downloaded from HP; after that I was able to boot into the UEFI menu. > Here's an image of how gparted sees the linux partitions and boot partition > as they are currently. > > On Tue, Sep 12, 2023 at 11:59 AM Randy Goldenberg < > [email protected]> wrote: > >> A BIOS boot partition would not typically have a file system. Why both a >> GUID signature associated with legacy BIOS boot and an efi executable would >> be on a partition labelled as a BIOS boot partition is a mystery to me. >> >> What is your goal? >> >> On Tue, Sep 12, 2023 at 7:31 AM Moses Gold <[email protected]> wrote: >> >>> Thanks. Does that mean that the grubx64.efi on this partition is >>> extraneous? >>> >>> On Mon, Sep 11, 2023 at 9:55 PM, Randy Goldenberg < >>> [email protected]> wrote: >>> >>>> EF02 is a BIOS boot partition. >>>> >>>> On Mon, Sep 11, 2023 at 6:04 PM Moses Gold <[email protected]> >>>> wrote: >>>> >>>>> The BIOS_grub GUID signature: >>>>> "48 61 68 21 49 64 6F 6E 74 4E 65 65 64 45 46 49 -- Hah!IdontNeedEFI" >>>>> is contained within my EFI partition after a recent grub install (grub >>>>> and >>>>> EFI added during same Linux installation). Specifically, the EFI >>>>> partition >>>>> begins at sector 1 of my boot device /dev/nvme0n1 and the BIOS_grub >>>>> signature appears at sector 2. gdisk says the following: >>>>> >>>>> Number Start (sector) End (sector) Size Code Name >>>>> 1 2048 1628159 794.0 MiB EF02 >>>>> >>>>> Is this the normal predicted configuration of BIOS_grub with an EFI >>>>> partition? >>>>> >>>>
