Re: [gentoo-user] New PC, new boot concepts

[Tom H]

On Fri, Dec 19, 2014 at 10:22 AM, Mick <michaelkintzios@×××××.com> wrote:
>
> Old dogs and new tricks springs to mind. I am building a new PC and what with
> UEFI, APUs and SSDs, it feels like that the world has moved a long way since
> the last time I had to install gentoo.
>
> I'll be taking my time to google, read and make appropriate selections, so
> please bear with me while I start relevant threads as necessary to complement
> my sparse knowledge in these topics. Starting from the top, with this thread
> I am trying to find out what is considered good practice as far as UEFI/MBR
> and boot management goes.
>
> The MoBo is capable of booting in CMS mode, but I am not sure if there are any
> benefits in creating a 2MB partition for a conventional MBR bootloader, or I
> should forego MBR altogether and go directly with a GPT FAT32 EFI System
> Partition (ESP).
>
> If the latter is the way to go and I forget all things I ever learned about
> MBR, does the 550MB FAT32 ESP partition have to be at the beginning of the
> drive?
>
> Is it beneficial to install a Linux boot loader/manager like GRUB2, or rEFInd,
> etc., or should I just use the kernel EFI Boot Stub to boot gentoo with? The
> PC will single boot in Gentoo, although I may drop in a sysrescuecd image for
> recovery purposes and would be nice to be able to boot this straight off the
> disk, without having to burn it on a CDROM. Is it simply a matter of adding
> the LiveCD iso in the ESP with a .efi suffix, or will I need to use efibootmgr
> to inform the UEFI about *any* kernel images in the ESP other than the default
> EFI/BOOT/bootx64.efi?

For refind and gummiboot, you have to enable the efi boot stub because
they're boot managers, rather than boot loaders like grub.

If you want to use the efi boot stub, whether directly or via
gummiboot or refind, you have to have the kernel (and initramfs if it
exists) on a fat partition. Unlike with bios firmware, you can have
them all co-exist.

AFAIK only grub can boot from an iso file. You have to have a
"loopback loop path_to_iso_file" line (which I think of as a "mount -o
loop ...") in that iso's menuentry stanza. And its "linux ..." line
will be dependent on the iso from which you're booting. The
systemrescue iso needs either "findiso=..." or "isoloop=...", I've
forgotten.