Simultaneous EFI and Legacy bootloader installation

[Vincent Danjean]

Le 30/03/2016 03:48, Stefan Lippers-Hollmann a écrit :
> Hi
> 
> On 2016-03-29, Mario Limonciello wrote:
>> On 03/29/2016 07:50 PM, Limonciello, Mario wrote:
> [...]
>>> I'd like to propose changing this and by default install both legacy and UEFI bootloaders on architectures that support both regardless of which mode the system is running in at installation. Making this change has a few obvious implications: * The installation disk would always be formatted GPT. * An ESP would always be created. * If the user is in legacy at installation time, it's not possible to create an EFI boot entry since EFI runtime services aren't present. The removable media fallback path (\efi\boot\boot$ARCH.efi) will need to be used to boot the system at this point and at some point create a "debian" NVRAM boot entry
>>> 
>>> I'm not aware of any modern systems that are unable to boot a GPT partitioned disk.  If there are systems like this in the wild, it would be worthwhile to leave support to install in MBR mode when doing an expert install so that people can still use them.
> [...]
> 
> At least well into 2009/ 2010 era systems (most of those are early UEFI based underneath, but only expose a mandatory BIOS CSM to the user), you can sometimes find mainboards which refuse booting from a disk that doesn't have a MBR partition with the bootflag set. On these systems it is often possible to trick them into booting by setting the bootflag on the protective MBR around the GPT partitions, although this is a blatant violation of the UEFI specification (and might break more modern systems).
> 
> Of course, most of the affected systems won't be detected as UEFI capable in the first place (because they will only allow booting via the BIOS CSM), but it's still something to be aware of.

  Hum...
  HP ZBook80 suffer from such problem, whereas they are recent.
  The Legacy BIOS cannot boot a GPT disc where the bootflag is not present
in the protective MBR :-(
  And the UEFI Bios do not read the NVRam entries. One has to manually
set the path to the grub loader in the EFI Bios setup (or to replace the
windows efi bootloader by the grubx64.efi file)
  I'm very disappointed by the HP ZBook current BIOS implementation.

  Regards,
    Vincent