I have recently built an SysV 7.10 LFS on hardware that has
UEFI enabled.
Whilst I followed the link in the LFS Book's
Section 8.4. Using GRUB to Set Up the Boot Process
to the lfs-uefi hint, I wanted to flag up something that, although
mentioned in passing in the hint, doesn't seem to get the "praise"
it deserves and would suggest that it might even warrant being
explcitly mentioned in the LFS Book itself.
Basically, with just the one modiciation needed to the kernel built
following the LFS Book's "good place to start", namely:
make defconfig
I was able to boot straight into my new LFS system.
What I found was that without just that one setting, as detailed
in the lfs-uefi hint
$ diff /mnt/usr/src/kernels/config-00{1,2}
526c526,527
< # CONFIG_EFI_STUB is not set
---
> CONFIG_EFI_STUB=y
> # CONFIG_EFI_MIXED is not set
$
I' d be told that the
Kernel doesn't support EFI handover
however once I had added in just that one Kernel Config setting,
I was able to boot into my LFS system using the host system's
grub.
Clearly, to make the LFS system capable of configuing a UEFI
boot environment, one needs to install the extra packages that
the lfs-hint outlines (which is what I am halfway through doing and
why I've recently posted some of my observations about pciutils
on the BLFS dev list!) however it did strike me that that one piece
of configuration could be mentioned in the LFS Book's kernel section,
so as to point out to folk how easy it is to make the LFS kernel capable
of being booted on a system that's already using UEFI.
Just a suggestion though,
Kevin
PS
The part of the lfs-uefi hint that has the info one needs,
albeit surrounded by some other stuff for deploying a
full-blown UEFI-capable LFS system, is the third of the
option lines in this bit:
---8<------------8<------------8<------------8<------------8<------------8<------------8<---
...
LFS CHAPTER 8:
KERNEL CONFIGURATION OPTIONS FOR EFI
CONFIG_EFI_PARTITION=y
CONFIG_EFI=y
CONFIG_EFI_STUB=y
(The above makes the kernel bootable from the EFI partition if
necessary)
CONFIG_FB_EFI=y
CONFIG_FRAMEBUFFER_CONSOLE=y
# CONFIG_EFI_VARS is not set
Do not enable this option. It creates runtime conflicts with
EFIVARFS which replaces it.
CONFIG_EFIVAR_FS=y
# CONFIG_UEFI_CPER is not set
# CONFIG_EARLY_PRINTK_EFI is not set
...
---8<------------8<------------8<------------8<------------8<------------8<------------8<---
but that's all that's needed, and the hint doesn't actually say that.
PPS
On my system, the EFI related (I grep-ed for EFI in the config file)
settings that the
make defconfig
had set were as follows:
CONFIG_EFI_PARTITION=y
CONFIG_EFI=y
# CONFIG_EFI_STUB is not set
CONFIG_FB_EFI=y
CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK=y
# EFI (Extensible Firmware Interface) Support
CONFIG_EFI_VARS=y
CONFIG_EFI_ESRT=y
CONFIG_EFI_RUNTIME_MAP=y
# CONFIG_EFI_FAKE_MEMMAP is not set
CONFIG_EFI_RUNTIME_WRAPPERS=y
# CONFIG_EFI_BOOTLOADER_CONTROL is not set
# CONFIG_EFI_CAPSULE_LOADER is not set
CONFIG_EFIVAR_FS=m
# CONFIG_EARLY_PRINTK_EFI is not set
# CONFIG_EFI_PGT_DUMP is not set
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