thank you for this feedback. Le ven. 16 déc. 2022 à 12:47, Pascal Hambourg <[email protected]> a écrit :
> On 16/12/2022 at 11:15, Pascal wrote: > > > > GRUB : > > > > INTEL/MBR GPT > > PARTITIONING PARTITIONING > > +---------------------+---------------------+ > > |MBR 1/3 |MBR 1/3 | > > |POST-MBR-GAP 2/3 | | > > |+-------------------+|+-------------------+| > > ||PART |||PART BIOS-BOOT 2/3 || > > ||/boot/grub/ 3/3 ||+-------------------+| > > BIOS ||... ||+-------------------+| > > BOOT || |||PART ESP (FAT) || > > || |||/boot/grub/ 3/3 || > > || |||... || > > |+-------------------+|+-------------------+| > > +---------------------+---------------------+ > > | | | > > | | | > > |+-------------------+|+-------------------+| > > ||PART ESP (FAT) |||PART ESP (FAT) || > > ||/boot/efi/ 1/2 |||/boot/efi/ 1/2 || > > UEFI ||/boot/grub/ 2/2 |||/boot/grub/ 2/2 || > > BOOT ||... |||... || > > || ||| || > > || ||| || > > |+-------------------+|+-------------------+| > > +---------------------+---------------------+ > > 1) There is no need for an ESP for BIOS boot. > 2) /boot/grub does not have to be in the ESP. > > > 3 steps for GRUB in BIOS mode and 2 steps in UEFI mode. > > > > in BIOS mode : > > first, BIOS load MBC (Master Boot Code - step 1/3 of GRUB) from MBR to > > memory and run it > > - with INTEL/MBR partitioning, GRUB will be chained from MBR, then to > > POST-MBR-GAP (step 2/3) and then to /boot/grub/... (step 3/3) > > "GRUB will be chained from MBR" makes no sense and does not fit between > 1/3 and 2/3. > > > - with GPT partitioning, GRUB will be chained from MBR, then to a special > > partition of type BIOS-BOOT (step 2/3 - can't use POST-MBR-GAP because > used > > by GPT) and then /boot/grub/... (step 3/3) > > From the GRUB boot loader point of view, both are exactly the same. The > GRUB boot image in the MBR does not read the partition table nor know > anything about the BIOS boot partition. The GRUB core image start sector > is embedded in the boot image in both cases. Only grub-install uses the > BIOS boot partition. > > > in UEFI mode : > > first, UEFI load an run a (GRUB) loader (step 1/2 of GRUB) located on ESP > > (EFI system partition formated with FAT file system) > > then the loader chain to /boot/grub/... (step 2/2) > > With secure boot, the UEFI firmware first loads shim which then loads GRUB. > >
