I know probabilly it's a really annoying noobish question ...
I' m not able to install SW 14.2 on my laptop in EFI mode:

- I want only SW 14.2 (so no multiboot by now)
- I'm using WD blue 640 GB HDD with the following part. scheme:
*1 100 MB (ef00) efi
*2 100 GB (8300) sys
*3 400 GB (8302) home
*4 96 GB (8200) swap -> (I know it's too much, it's just a test)
NB: used cgdisk on an unformatted GPT disk

- No problem during installation
- Skip Lilo and Install ELILO
- Reboot
- Non Sys detected

Tried 1000 times ... always the same

What do I miss?
Where is my fault?

Thanks in advance

Note: I know I can live perfectly with MBR, but EFI is the "future" and It has great advantages if one decides to multiboot, so I'd like to learn how to manage.

Do you have the BIOS/UEFI set to legacy mode? That could easily prevent UEFI from being detected.

Re-cecked again, but no, no secure boot, no fast boot, no software protection ... Nothing.
I'm suspecting a buggy HP Firmware: on HP webpages it seems this EFI version creates problems also with windows, plus there are many strange things I noticed during my test:

- even if you press F9 (boot menu) or F10 (bios setting) and the sys seems to get the comand, but it's not so you need a "hard reboot" (via on/off switch)
- even if SW installer finds the vfat partition, does not create a menu entry and if try to edit elilo.conf I don't find elilo.conf
- also tried other bootmgr (grub & refind) but by now I was not able even to install them!

By the way ... is there a way to test a EFI installation in a safe way?
I tried once on Vbox, but there the problem is after you select the kernel to boot the screen becomes blurry and full of unreadable fonts (?!?)
also tried to install follwing these instructions:
http://docs.slackware.com/howtos:sla..._uefi_hardware

Please also note that it seems that a firmware update is possible only via software that is only for windows ... :-(
It seems there's no way ....

When you select F9 for the boot menu, do you notice two entries for your USB drive? I remember on mine it had two, one for UEFI and one for legacy (although, I think only the UEFI was labeled as such).

Unfortunately, I wasn't actually installing things, so I had left my system using the regular lilo method (it was installed on older hardware that didn't support UEFI). So, I don't have much experience with UEFI. Maybe another forum member with more knowledge will chime in.

And it is sad that sometimes you can't update firmware unless you're running Windows. However, if that is the only way to update the firmware, it might be worth it to reload Windows to get a properly working UEFI installed.

If I press F9 and the USB stick is plugged I get:

boot device not found
Please install os on your HD
Hard disk - (3F0)
F2 Sys Diagnostic
for more information, please visit: www.hp.com\techcenter\starup

If I press F9 and after the menu is displayed I plug the USB, so I'm able to select boot from EFI file from following menu:

BOOT OPTIONS:
Please Select
Notebook Upgrade Bay (UEFI)
Notebook Ethernet (UEFI)
Boot from EFI file
Notebook Hard Drive
Notebook Upgrade Bay

From Boot from EFI file then I select SLACKDVD (my usb stick), then EFI, then BOOT, then bootx64.efi
This is the only way I had to boot from USB and start installation; USB is created with RUFUS (under windows) and the volume is labeled to be complaint with both GPT and MBR.

About the Partitioning (as already mentioned)
*1 100 MB (ef00) efi
*2 100 GB (8300) sys
*3 400 GB (8302) home
*4 96 GB (8200) swap

Also tried different formatting (I tried with 500 MB dedicated to boot) but with same results.

Please also note that (as suggested from HP forum) I changed the bay, using the first one instead off the second one
... Always the same

Thanks for the link from Arch page! I'm trying to understand it :-) there's a lot of "recompile the kernel ... edit this here ... ect" that are far beyond my noob comprehesion :-D so probabilly I need a lot of time to understand it (forgive me if i won't give you a feedback in very short time).
A first impression about that may be "hey, if I need to customize a kernel to install a linux distro to do some practice about that linux distro, makes no sense: it's the same of saying that if you want to learn you had to be already an expert", but don't take it as an offence, I appreciate your help and I'll try to understand better the contents before giving up ... XD

If you have access to another computer with windows on it there appears to be a way to prepare a usb stick for upgrading the uefi firmware. Take a look at this page:
https://support.hp.com/us-en/document/c00042629 and scroll down to the the section named "Updating the BIOS when Windows does not start (Windows 10, 8, 7)"

Thanks for suggestion!
I tried described process to update BIOS, but the damn firmware is unable to load USB/USB driver after reboot so it doesn't find the stick ...
Anyway ... installed Win 7 and succesfully update the firmware.
Just for a test I tried to install another distro with EFI support: Fedora 25.
Fedora comes with a usefull tool (Fedora Media Writer) to create a bootable USB, that tool is also able to create custum ISO (I was also able to install slackware iso w/o any issue!).
During installation Fedora failed to install bootmanager (... interesting info; damn HP EFI firmware!)
Just to do another test I tried SW 14.2 EFI installation once again using the usb created with Fedora Media Writer (before, I checked MD5 of my iso, it's ok) ... just to exclude it's a rufus related problem.
When it comes to ELILO this time the installer asked me if I want to create boot menu entry (never happened before), so I said YES! and rebooted.
Still does not work, but another issue comes up: I found now two broken entries in boot menu referring to Fedora!
This even if I wiped the GPT 3 times and recreated the partition table...
Don't know what to think ... maybe I sucks at EFI understanding and configuration, but I'm also quite sure the firmware is broken.
By the way it seems that fedora is at least able to create entries but not able to install a bootmgr properly, SW install no...
Is there any other suggestion?
Thanks in advance

Personally I like uefi and it truely is the way to go but I will admit that there are some poor implementation of it, especially in the early years. Sounds to me like there are firmware problems with creating and keeping boot entries in to NVAM. You do appear to be able to boot in uefi mode from a USB so I would recommend that you flash rEFInd to a usb stick using dd and this image;
http://sourceforge.net/projects/refi...7.zip/download
Once you boot it up, reFind will scans your disk ESP for bootable images, such as bootmgr.efi, bootx64.efi, and elilo.efi and present boot entries for each. It does not need or depend on the boot menu entries in NVAM.
If you can then boot into the hard drive installed Slackware, you will know that the problem is with the NVAM boot entries, and not the UEFI Slackware installation.

Sorry for late reply, I was on business trip ... (w/o my personal laptop ... :-( )

I tried what Rich (laprjns) tolds and ... it works! Refind is able to scan for bootloader and is able to detect SW 14.2 and boot it successfully!
(refind is also able to find fedora partial dirt installation but obvoiusly is not able to boot from those kernels, but this is perfectly logic).

So, last step, it is possible to install refind after installing slackware? if yes how? before I tried but I wasn't able ... could you please suggest some proper and safe method?

Thanks in advace! ... and @ Rich (laprjins) you are my hero of the day! :-D

Rich has packaged and themed refind for Salix, you will find it in this directory :
http://slackware.uk/salix/x86_64/14.2/salix/a/
I didn't try it but it is certainly usable on Slackware64-14.2.

Alternatively you can get a SlackBuild @ http://slackbuids.org:
https://slackbuilds.org/repository/14.2/system/refind/

If you install using the Salix package then rEFInd will be completely install and will work on the next boot. If I recall correctly, the SLACKBUILD requires addition configuration after installing the resulting package. I believe after you installed the Slackbuild package you then need to run the refind-install script.

Hello, I'm back, sorry for long time, but I've done a lot of test...
I'm able to install rEFInd, but even if efibootmgr propt that it is default boot manager, the bootorder is overwritten every boot process.
The only case in which I was able to make permanently refind is with fedora 25, that install a sort of grub corresponding to a /boot/efi/EFI/boot64.efi file
Copying refind_x86_x64.efi file to it I could get a sort of text menu that make me able to choose which efi file boots.
This is far from a fix, and far from a good implementation of refind on my hp8760w ....

I'm more and more convinced that uefi does not worth such efforts.

Thanks anyway for help to everybody!

Well maybe for your computer's implementation of UEFI. Give this a try

http://www.rodsbooks.com/refind/installing.html#naming

Oh yes, sorry for misunderstanding! I'm absolutely talking about this HP UEFI firmware version only! Nothing against UEFI in general.
I'll experiment a bit following the guide-lines provided by your link.

Thanks for your follow up!

SOLVED:

This link is the Key for the solution:
https://askubuntu.com/questions/1502...lly-into-12-04

This HP Bios version is actually broken ... Basically it is able to boot only from this file

/boot/efi/EFI/boot/bootx64.efi

So if you overwrite it with (for example) /boot/efi/EFI/slackware14/grubx64.efi ("slackware14" is my efibootmgr entry)then you get permanent UEFI boot on your system.

The same method works with refind, but you have to copy all "refind" folder (should be located at /boot/efi/EFI/refind)if you want to have a full grafical "rEFInd" environment; in case you only copy refind_x86_x64.efi to bootx64.efi you have a similar situation when you press F9 (choose boot menu) and select "boot from EFI file", but without to be get "os not found" if you are not fast enought to press F9.

This tricks should be valid with elilo too (if you copy the elilo.conf file in the mentioned folder, basically every bootloader is fine except for syslinux that seems not fit with this broken firmware.

Thanks to everybody for your follow up, you make this comunity great! :-)