rEFInd doesnt' auto-detect this Linux Distro

[Michele]

Hi guys, I have a uefi Windows 10 tablet (dell venue 10).
I successfully installed refind and debian on this tablet... Refind auto-detected Debian and now I can perfectly use 2 OSs.

Now I want to also try Slitaz (mini linux distro) on this device but I have this little problem...
Slitaz works just in the old BIOS mode (so I can't even boot it from a usb pendrive on this tablet)
So I copyed its 2 necessary files (vmlinuz and .img) into the ESP and in an empty ext4 partition
Anyway refind doesn't detect this OS, I also tryed to edit the config file and enabled the deep scan for bios/legacy OSs but I had no results...

Please can anyone help me?
Should I manually create a boot-entry for this OS?

[Roderick W. Smith]

I've never tried that distribution; however, some possible reasons rEFInd might not detect its kernel include:

• Wrong bit depth -- If the kernel is 64-bit and the EFI is 32-bit, or vice-versa, rEFInd won't show the kernel as a boot option.
• No EFI stub loader -- If the distribution is, as you say, intended only for BIOS-mode boots, then the kernel may well omit the EFI stub loader, which rEFInd requires to launch the kernel. If this is the case, then rEFInd won't show the kernel in its menu.
• Wrong location -- rEFInd doesn't scan everywhere; it scans the root (/) directory, /boot directory, and most subdirectories of /EFI (to a depth of one; the is, /EFI/foo, but not /EFI/foo/bar). If you put the kernel elsewhere, rEFInd won't find it, unless you use the also_scan_dirs option in refind.conf.

Even if you can get rEFInd to recognize the kernel, that's likely not the end of the problem. In most cases, you must pass appropriate options to the kernel, and you'll need to dig into the distribution's standard boot loader configuration file to figure that out. You may need to "translate" some options to a form that rEFInd will be able to handle.

If rEFInd can't handle the kernel itself (say, if it lacks the EFI stub loader), you may be able to use another boot loader (GRUB 2, ELILO, etc.) to launch the kernel, and continue to use rEFInd as a boot manager to switch between distributions. You'll need to set up this other boot loader yourself, though.

Note that you may need to jump through these hoops twice -- once to get the installation medium to launch and a second time to get the installed version of the OS to boot.

[Michele]

Hello Roderick, many thanks for the reply.
1) About bit depth
This tablet has a 64bit hardware but it came out from the factory with a 32 bit Windows and i'm pretty sure its UEFI works in 32bit mode (never resulted to boot OSs from "bootia64.efi" files...)
Slitaz Kernel supports just 32bit hardware but it should work (the debian version I use it's also 32 bit)...

2) About EFI stub loader
Yes, Slitaz is intended only for BIOS-mode boots. So, if f the Slitaz kernel omits the EFI stub loader, will Refind never show the kernel? Did I get it right?
(In this case I can't do anything)

3) About the location
So should every kernel be located only in the ESP partition? (it's useless to put it in any other partition)

In conclusion, I have to create a Grub2 entry for refind and boot Slitaz from it...
Please Can you link me a guide or tell me how to do it?
I can use both Win and Debian on this tablet so it's won't be that difficult :)

[Roderick W. Smith]

Many tablets have 64-bit CPUs but 32-bit EFIs. If you've got a 32-bit Windows, then you almost certainly have a 32-bit EFI. If you can boot rEFInd, then its about/info screen will reveal the EFI's bit depth with certainty.

32-bit kernels can include the EFI stub loader. (Ubuntu's and Fedora's both do, for instance, even though neither OS officially supports EFI-mode booting on 32-bit platforms.) I can't speak to Slitaz, since I've never used it. You're correct in your summary that rEFInd will not show kernels that lack the EFI stub loader. I don't know that this is the source of your problem, though.

Kernels can reside somewhere other than the ESP; that's the point of rEFInd's filesystem drivers -- by using a driver, the EFI, and therefore rEFInd, can read the kernel from some Linux native filesystems. (rEFInd provides drivers for ext2/3fs, ext4fs, ReiserFS, and Btrfs, plus non-Linux-native filesystems NTFS, ISO-9660, and HFS+.)

I'm afraid I can't provide step-by-step instructions for creating a GRUB 2 (or other boot loader) entry for booting the Slitaz installer, and I don't know where such instructions might exist. I suggest you ask about this on a Slitaz forum; the people on such a forum are more likely to be familiar with that distribution than I or other people here are.

[Michele]

Thanks anyway. Sadly the community that surrounds this distro in not so big, they can' t help me for now. But I'm "studying" and I'm finding the way to boot the OS, I'll write a guide if I result to boot the OS