Re: Purpose of 'legacy_boot' attribute

[Chris Murphy]

On Oct 19, 2011, at 9:37 AM, Keshav P R wrote:

> On Wed, Oct 19, 2011 at 20:46, Brian C. Lane <address@hidden> wrote:
>> I was also just wondering if we (Fedora) should be setting legacy_boot
>> on /boot partitions instead of the boot flag, since the latter writes an EFI
>> system GUID to the partition type.
> 
> 
> Yes. 

The more I think about this, I'm inclined to disagree. I think that unless 
there is a specific need for setting this attribute, it should not be set, 
rather than as some kind of default. To my knowledge the EFI spec doesn't say 
these GPT attributes should be set by default, so I feel that they should only 
be set when needed for an express purpose.

So unless someone can provide a compelling reason why an installer should set 
'legacy_boot' attribute, when neither that installer nor its installed 
bootloader or system require the attribute being set, my position is that 
Fedora should not set 'legacy_boot' (or 'hidden' for that matter), except 
expressly when making hybrid EFI/BIOS boot sticks.

Otherwise it puts everyone else's installers who might be negatively affected 
by that positive state in the position of having to clear the attribute. That's 
a lot of unnecessary work.

At least in all of my testing with hard disks, and both grub legacy (RH GPT 
support), and Grub2, and Grub2-EFI I have not found any difference in boot 
behavior as a result of the 'legacy_boot' flag being set on linux /boot 
partitions. So I'd say, don't set it in normal installed that don't require 
gptmbr.bin.

Chris Murphy