[lfs-support] EFI, UEFI and LFS--Complicated, Confusing or Can of Worms

Craig Magee psybertao at gmail.com
Fri Nov 1 05:13:58 PDT 2013


I use UEFI by putting the kernel and an (optional) initrd in the EFI
partition.  The kernel has EFI stubs if you enable the option.
You can pass kernel parameters in the UEFI boot entry or put them in the
kernel itself.  Both options are available towards the bottom of 'Processor
type and features' in the kernel configuration.
The only gotcha is booting 32-bit, my UEFI system only supports booting
64-bit so I had to install a 64-bit GRUB to then boot a 32-bit kernel.

I find UEFI is actually pretty neat and removes the need for an additional
bootloader.  Anytime I want to boot anything other than the default
(including from CD or USB) I press the escape key and select the option I
want.  GPT partitioning rocks as well (though you don't need to use UEFI to
take advantage of that using Linux; you do for Windows).


On 31 October 2013 06:02, Casey Daniels <mailinglist at cd.kcfam.net> wrote:

>
> On 10/30/2013 12:47 PM, Dan McGhee wrote:
> > On 10/30/2013 11:26 AM, Casey Daniels wrote:
> >> On 10/30/2013 12:17 PM, Dan McGhee wrote:
> >>> Anyway, I just wanted to share what I have discovered.  This may lead
> to
> >>> posts like, "I did this and it didn't work.  The book needs to be
> >>> changed."  The implementation of LFS, configuring and installing both
> >>> the kernel and GRUB can be successful regardless of how the BIOS boots.
> >>> There is a learning curve though. And some of GRUB's building and
> >>> installing arguments need to be a little different.
> >>>
> >>> Dan
> >>>
> >> I played with UEFI Boot for almost a week and couldn't get anywhere with
> >> it.  I could get Grub Loaded, and and I could get grub to find the
> >> Kernel, but then it would ALWAYS fail at some memory point during the
> >> Kernel load, and I played and played with the kernel for that week and
> >> it keep freezing at the same point.
> >>
> >> The thing with UEFI Boot is you don't need Grub to boot if you don't
> >> want to.  If you have a Linux only or Windows only, computer you can
> >> actually boot with out user input without a bootloader.  From my
> >> understanding though if you have a dualboot system you need at a minimum
> >> a boot manager to boot without user intervention.  If you don't mind
> >> typing a few commands you can boot with out a boot manager or bootloader
> >> in a dual boot system, you just have to understand the UEFI Shell you
> get.
> >>
> >> Casey
> > Casey, your experience confirms what I have learned by reading and my
> > own experience. Yes, on dual boot you need a manager to get to the
> > loader you want. That's one of the functions of the EFI partition. I
> > don't want to address your specific situation until I have practical
> > experience with my LFS build and that won't be for a couple of more days.
> >
> > If you have not been successful in booting your LFS system and you want
> > to "play," I recommend turning off secure boot, checking your kernel
> > configuration to support efi and running <grub-install --help> to select
> > the arguments you use for grub. I just finished reading "grub-install"
> > and it looks like it should detect your partition type--MBR or GPT. I
> > don't want to suggest anything definite because I haven't "proved" them
> > with my own experience. One of the possible outcomes is that your
> > computer won't boot. I would rather be the victim of my own eperiments
> > rather than having someone else be that victim. :)
> >
> > Dan
> >
>      I had no problem getting the Boot Loader working, surpurising
> enough, though I did learn that in order to get grub to do a proper UEFI
> Install, the system your installing it from had to have booted from
> UEFI.   I had Grub find the Kernel in the proper place, and start to
> load, but the Intel board I use does some type of Memory Check and
> always fails at the same Memory Address.  So I don't know if I had some
> incompatable Option in my Kernel or there is a issue with Intel's UEFI
> Implentation (Which from what I was able to read on the subject this
> might be the case, I think it trys to protect that Memory Address and
> the Linux Kernel trys to get into that specific Address).  Yes I did
> have Secure boot turned off.
>      I really don't care about UEFI boot for the current hardware of my
> servers, but from my understanding is my Intel Boards are UEFI boards
> that emulate the orginal BIOS for Compability reasons, however some
> boards are already coming out as UEFI only and it probably won't be too
> long before most boards don't have a legacy mode.
>
> Casey
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