On 08/21/2014 01:28 AM, Alan Feuerbacher wrote:
On 8/21/2014 12:27 AM, Bruce Dubbs wrote:
Alan Feuerbacher wrote:
<As Ken says, me snips much.>
As for getting a UEFI bootloader working, I researched the matter
extensively online late last fall, without any real resolution. I
concluded that a lot of UEFI stuff was being kept secret by various
players, from Fedora to ASUS to pretty much everyone else who had
actually got UEFI bootloaders to work. I know that some companies such
as Fedora have agreements with BIOS makers to do stuff that the average
hacker like me can't do. At least, not easily. I don't remember finding
a specific reason for the secrecy. I finally decided that it was due to
a combination of key players really not knowing what they're doing in
terms of the UEFI "standard", along with a reluctance to admit that to
their customers.
Well you could just disable UEFI. That's what I did. The only OS that
really needs it is Windows.
-- Bruce
Thanks!
It's almost sounding like UEFI is a big nothing, except for Windows. No?
By now I had hoped to make more progress in booting LFS in UEFI using
LFS-7.5. But, alas, life interfered so I'm waiting for 7.6 to continue.
First of all, it's important to make sure that the different terms are
not "muddied." Here's the list I learned that causes the most confusion:
BIOS, UEFI, MBR, Secure Boot, Boot Manager and Boot Loader.
UEFI is hardware and its standard, if it hasn't yet certainly will,
replaces BIOS. The major difference is the bit size between the two. I'm
going completely from memory here: BIOS is 16-bit and UEFI is 128. BIOS
is still used to refer to that part of a computer which does the initial
boot, and is not quite technically precise. (On my HP laptop, I just
installed a "BIOS" Update, and I must enter BIOS Settings to change
things around, although I have UEFI firmware.)
MBR is an actual place on a BIOS based machine who's function most of us
know. It's the place where GRUB lives. The MBR Layer is what UEFI uses
for it's Legacy Boot option, and acts like an MBR. GRUB also lives there
if you have set up "Legacy Boot" and followed the instructions in the
LFS book. UEFI is many times used synonymously with Secure Boot. This is
not correct.
UEFI uses what I call an intermediate step when it comes to booting.
Classically, we LFSers are used to booting into a GRUB menu. GRUB,
however, although I think it's morphing, is a boot loader. UEFI uses a
*Boot Manager*--the intermediate step--to access a Boot Loader. Secure
Boot throws in a monkey wrench.
Although turning it off and on is accessed through "BIOS" settings,
Secure Boot is a software thing. When enabled, it looks in the EFI Boot
Partition--the analogue of MBR--to determine which boot loaders are
"secure." It does this by finding signed *.shm files on that partition.
I *think* that what Secure Boot was designed to protect against is not
possible anymore. I do *know* that Microsoft, after a fee, issues
"signing approval" for the *.shm files. At least Ubuntu and Fedora have
paid and that's why they can be used with Secure Boot.
You, allegedly, can boot anything from anywhere with Secure Boot set to
'OFF' in the "BIOS." It's just a matter of putting it in the right spot
and finding it.
This is where the Boot Manager comes in. For Linux, the ones with which
I'm familiar are gummiboot, rEFInd and efibootmgr. However, to build and
install these things, the kernel must be correctly configured and the
EFI Boot Partition mounted.
If you're interested in pursuing this the following thread from the
archives contains more detail:
http://lists.linuxfromscratch.org/pipermail/lfs-support/2013-December/046286.html
That is the most concise. There are other threads from last November and
December, which are, if not informative at least, entertaining. :)
I am most interested in anything you do in this area. As, I said, after
LFS-7.6 is released I will continue in my research.
Dan
Alan
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