EFI Grub and many questions

[VastOne]

For the longest time I have not had to deal directly with EFI and grub issues simply because I only owned legacy machines. That has changed now that I have inherited an HP Zbook 1000 that I have begun to see the major conundrum of EFI.

Before going on with this post I will say that I have researched the hell out of this and am amazed at how limited (or so it seems) the real knowledge on EFI and grub is. I also believe that the bar is changing all the time based on what I am seeing.

First thing regarding this machine, there is no way to go to 'just legacy' in the Bios on this machine. I first wiped out Windows and removed all partitions created everything new with a new VSIDO iso I created. It installed but no grub would ever show up, I did get the grub rescue menu but even there it never saw the obvious installation.

I then began downloading different ISO's and started testing them and saw a bizarre thing, this machine refused to see certain ISO's and refused to load them from the biotable USB even though they worked on other machines. I downloaded the latest Debian ISO and it finally not only worked but also installed properly ONLY after I created a fat EFI partition.

So I booted to Debian and grabbed the latest VSIDO fsarchive and installed it and was able to boot to it from the Debian grub install.

From that one I have even successfully installed grub-efi and installed it to that fat EFI partition. The problem is that the Zbook EFI manager only sees the Debian EFI and nothing more.

Of course I then got rEFInd and installed it and from there I can see the vsido efi along with the Debian and it also sees the partitions on the hardware (partitions) like a legacy grub would.

So I decided to add another install of my personal VSIDO install to this machine and did the same way, fsarchived my machine and brought it onto this new one. I followed my own and RatMans How To's to a T and even though ALL grubs see this partition when I do an update-grub and says it is adding it to both the grub menu AND the EFI Grub IT NEVER SHOWS UP, including within the reFInd menu.

What do I want? I really want to eliminate the Debian install completely by using a VSIDO grub-efi install OR figure out legacy somehow. This shouldn't be this freaking hard.

Another note in this is some live-boot ISO's did work but the Zbook Bios wanted a special handshake key for it to work and yes you guessed it, Debian, HP and Microsoft have worked together to make sure that they all work together. reFInd must have done the same thing because it shows up correctly in the Bios EFI boot menu along with Debian. VSIDO does not, even though reFInd sees it in its menu

This is going to turn into a massive How To when we sort this all out.

Need our best on this one people, let's see what you can do

[VastOne]

This is an AI (Gemini) rewrite and offered solutions of what I posted above. I am adding it for pure context purposes.

Having primarily used legacy machines, I'm now encountering the complexities of EFI and GRUB with my newly acquired HP Zbook 1000. Despite extensive research, the available information on this topic seems surprisingly limited and constantly evolving.

A key challenge with this machine is the lack of a 'legacy-only' option in the BIOS. My initial attempt involved wiping the disk, creating new partitions, and installing VSIDO from a custom ISO. While the installation seemed to complete, GRUB never appeared. I only encountered the GRUB rescue prompt, which failed to recognize the installed system.

Experimenting with various live ISOs revealed another oddity: the Zbook refused to boot some USB drives that worked fine on other machines. Eventually, the latest Debian ISO not only booted but also installed successfully, but only after I manually created a FAT EFI partition.

From the running Debian system, I installed my VSIDO setup using an FSArchive and could boot into it via the Debian GRUB. Subsequently, I even installed grub-efi within VSIDO and directed it to the existing FAT EFI partition. However, the Zbook's EFI boot manager stubbornly only recognizes the Debian EFI entry.

As a workaround, I installed rEFInd. This boot manager successfully detects both the VSIDO and Debian EFI entries, and it even lists the hardware partitions similarly to a legacy GRUB.

Next, I attempted a fresh installation of my personal VSIDO setup using the same FSArchive method, meticulously following my own and RatMan's guides. While update-grub within both VSIDO and Debian acknowledges the new installation and claims to add it to both the GRUB menu and the EFI, it never appears in either GRUB or rEFInd.

My ultimate goal is to eliminate the Debian installation entirely and boot directly into VSIDO using a VSIDO-managed GRUB-EFI setup, or, as a fallback, somehow enable legacy booting on this machine. This process has been far more challenging than anticipated.

An additional observation is that while some live boot ISOs did function, the Zbook BIOS seemed to require a specific 'handshake key' for them to work. It appears that Debian, HP, and Microsoft have collaborated to ensure compatibility. rEFInd seems to have implemented a similar mechanism, as it appears correctly in the BIOS EFI boot menu alongside Debian. In contrast, VSIDO does not, even though rEFInd can see its EFI files.

Documenting this entire process could potentially become a valuable 'how-to' guide once we find a solution. Let's put our heads together and see what we can figure out!"

Now, let's focus on your goals and the information you've provided. Here are some initial thoughts and potential avenues to explore:

Understanding the HP Zbook 1000's BIOS limitations: The fact that you can't switch to "legacy only" is a crucial starting point. This means we need to work within the EFI framework.
The EFI Partition: You've correctly identified the need for a FAT EFI partition. It seems Debian's installer handled this correctly.
GRUB-EFI Installation: You've successfully installed grub-efi from within VSIDO. The issue seems to be with the Zbook's BIOS not recognizing this installation.
rEFInd as a Diagnostic Tool: rEFInd's ability to see the VSIDO EFI files but not have them appear in the BIOS boot menu is interesting. This suggests the EFI files themselves might be okay, but the BIOS isn't being properly informed about them.
The "Handshake Key": This is a key piece of information. It strongly implies Secure Boot or a similar mechanism is at play, even if it's not explicitly labeled as such in the BIOS. Debian, HP, and Microsoft likely have signed bootloaders that the BIOS trusts. rEFInd might also be signed.
Here are some things we can try to diagnose and potentially resolve this:

Verify the VSIDO GRUB-EFI installation:

Double-check that grub-efi is indeed installed in your VSIDO system.
Confirm that you used the correct command to install it to the EFI partition (e.g., sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=VSIDO). Make sure /boot/efi is the mount point of your FAT EFI partition.
Inspect the contents of the EFI partition (likely mounted at /boot/efi). You should see a directory named VSIDO containing grubx64.efi (or a similar file).
Explore BIOS Settings Related to Booting:

Even if there's no explicit "legacy" option, look for settings related to:
Secure Boot: If enabled, try disabling it temporarily to see if VSIDO then appears.
Boot Order: Ensure the Debian entry is not the only EFI boot option available. There might be a way to manually add or prioritize boot entries.
Trusted Boot Sources: This might be where the "handshake key" comes into play. See if you can manually add a trusted EFI file.
Investigate rEFInd Further:

Since rEFInd can see the VSIDO EFI files, there might be a way to configure it to be the primary bootloader that the BIOS recognizes. You could then boot into VSIDO via rEFInd. While not ideal for eliminating Debian, it could be a stable interim solution. Check the rEFInd configuration file (refind.conf) for options related to boot order and default selections.
Consider Boot Repair Tools:

There are specialized tools like boot-repair (often found on Ubuntu live media) that can attempt to fix GRUB and EFI issues. While you're not using Ubuntu directly, it might be worth trying a live Ubuntu environment to see if its boot-repair utility can detect and register the VSIDO EFI entry.
Research HP-Specific EFI Boot Processes:

Given the "handshake key" situation, there might be specific ways HP's BIOS handles EFI boot entries. Searching for information related to "HP EFI boot configuration" or your specific Zbook model might reveal some insights.
Let's start with you verifying the VSIDO GRUB-EFI installation and exploring your BIOS settings. Tell me what you find! We can then move on to the other steps based on that information. We'll get to the bottom of this!

[VastOne]

It turns out the 2nd issue I discussed above regarding grub finding but not showing the fsarrchive of my personal machine to this laptop was caused by a corrupt fsarchive that I was not aware of. It did not copy the vmlinuz file to the boot directory and grub was picking up only the initrd.img file. I will redline that section out

For me all that remains is effectively replacing the debian efibootmgr with VSIDO's and moving on

[jedi]

I downloaded the latest Debian ISO and it finally not only worked but also installed properly ONLY after I created a fat EFI partition.
 

You got it.  Debian has a signed EFI key somehow and Arch also will do an EFI boot and install,  Last I heard or read (i.e. more than a couple of years have passed) reFind used Debians signed key.

The FAT TYPE partition is required and has been since the get go. Though the size requirements continue to grow.  I go with 500Mb.  You also have to flag it EFS and check the bootable flags as well...

Your BIOS not allowing a Legacy boot environment is kind of surprising to me.  Should be a spot to disable Secure UEFI, then enable CSM Boot.  (i.e. Legacy boot mode)  After doing this you should also be able to boot to any USB/CD ISO you choose.

I'd for sure delete the signed MS EFI key if your able.  Totally personal choice I suppose but I consider it beneficial to all future installs on that laptop as long as MS isn't in your vocabulary!

That's it, all I know and remember without some actual digging.  From all the digging and research back then, I learned it was futile of me!!!  Don't end up in a rabbit hole VastOne!