elilo, booting with BIOS options decode above 4g + resize BAR

gdiazlo · 01-26-2021, 03:26 AM

I am unable to boot Slackware using elilo when the BIOS has enabled the Decode Above 4GB and the Resize BAR support. I can boot it with grub and with UEFI stub, but not with elilo.

Does anyone experience something like this?

Didier Spaier · 01-26-2021, 03:54 AM

Well, I don't know. Maybe someone will look into the source code of elilo? That could be Patrick Volkerding, who somehow adopted this orphan, certainly not me.

Meanwhile (sorry to state the obvious), if you are a gamer don't use elilo, else disable these features in you cards' firmware menu.

This being said I fail to see how allowing a better sharing of VRAM between the CPU and the GPU can impact the OS loader, but maybe it does?

gdiazlo · 01-26-2021, 04:47 AM

I think I am going to use uefi to boot the kernel directly, for this and other reasons (like the uefi framebuffer console).

On the other hand, it does not work with my particular set up, it might work for others. it can be a problem with my PC, not with elilo :?

Anyway, what I was trying to achieve posting it here is that someone might have a similar situation in the future and can find an alternate way of booting Slackware, and also for getting feedback from others that might be able to try it on their systems.

I am not familiar with the bootloader code, so I don't know. The fact that kernel does not load and hang without any message besides loading linux with elilo, but loads as expected using grub or uefi seems to me like something between elilo and the kernel is not working for this setup.

Martinus2u · 01-26-2021, 06:37 AM

just out of interest, what is meant by "use uefi to boot the kernel directly"?

gdiazlo · 01-26-2021, 07:09 AM

You can boot a Linux kernel without a bootloader. Just with add a boot entry with efibootmgr pointing to a Linux kernel (with its initrd) in the EFI partition. To choose what to boot, use your UEFI boot selection.

As a reference:
https://wiki.archlinux.org/index.php/EFISTUB
https://docs.slackware.com/howtos:sl...uefi_and_elilo

Code:

# efibootmgr 
BootCurrent: 0005
Timeout: 1 seconds
BootOrder: 0005,0000
Boot0000* Windows Boot Manager  HD(1,GPT,59334c72-26b1-6649-97f8-25ce947eec3c,0x800,0x100000)/File(\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}...b................
Boot0005* Slackware Current     HD(1,GPT,59334c72-26b1-6649-97f8-25ce947eec3c,0x800,0x100000)/File(\EFI\SLACKWARE\VMLINUZ)r.o.o.t.=./.d.e.v./.s.d.a.2. .i.n.i.t.r.d.=.\.E.F.I.\.S.l.a.c.k.w.a.r.e.\.i.n.i.t.r.d...g.z. .r.o. .v.g.a.=.c.u.r.r.e.n.t.

Didier Spaier · 01-26-2021, 07:25 AM

To elaborate a bit an EFI stub is a kernel wrapped in an EFI OS loader. Then the kernel is seen by the firmware just as an EFI OS loader, hands over the system to it and the EFI code in the EFI stub bootstraps the kernel. You can also embed an initrd in the stub, but then of course you will need to rebuild the stub (including the kernel) every time you modify the initrd. This is a safe way to boot in EFI mode but can be a maintenance burden as if your distribution provides a new kernel you will have to re-build it yourself. Not an issue for the Gentoo/Funtoo and maybe Arch users, probably one for most Slackware users, and I won't even mention users or Ubuntu or Mint

keefaz · 01-26-2021, 07:45 AM

I checked and I have Decode Above 4GB enabled in my Asus z97 EFI settings (no Resize BAR option), elilo and kernel boot just fine...
Did you try with the vga kernel parameter removed in your elilo.conf?

Martinus2u · 01-26-2021, 07:59 AM

Thanks! I switched to an EFI mainboard only a few weeks ago, and it seems I'm still not at the bottom of the pit...

keefaz · 01-26-2021, 08:16 AM

Quote:

Originally Posted by Martinus2u

Thanks! I switched to an EFI mainboard only a few weeks ago, and it seems I'm still not at the bottom of the pit...

Make sure you have a media installer ready somewhere to repair boot issues, it can happen if you have a multiboot setup or update EFI motherboard firmware etc

gdiazlo · 01-26-2021, 09:03 AM

I do not need to rebuild the kernel nor to rebuild the efi boot entry, just copy vmlinuz and initrd distributed by slackware into the EFI partition. If you use a custom initrd, then on each update you need to uptade it as you will need with a boot loader :? I don't see why it is a bad option for a slacker too.

Quote:

Originally Posted by Didier Spaier

To elaborate a bit an EFI stub is a kernel wrapped in an EFI OS loader. Then the kernel is seen by the firmware just as an EFI OS loader, hands over the system to it and the EFI code in the EFI stub bootstraps the kernel. You can also embed an initrd in the stub, but then of course you will need to rebuild the stub (including the kernel) every time you modify the initrd. This is a safe way to boot in EFI mode but can be a maintenance burden as if your distribution provides a new kernel you will have to re-build it yourself. Not an issue for the Gentoo/Funtoo and maybe Arch users, probably one for most Slackware users, and I won't even mention users or Ubuntu or Mint

gdiazlo · 01-26-2021, 09:06 AM

Yes..I tried without vga parameter and with vga=current. It can be totally related to my bios/motherboard

Quote:

Originally Posted by keefaz

I checked and I have Decode Above 4GB enabled in my Asus z97 EFI settings (no Resize BAR option), elilo and kernel boot just fine...
Did you try with the vga kernel parameter removed in your elilo.conf?

keefaz · 01-26-2021, 09:23 AM

Quote:

Originally Posted by gdiazlo

Yes..I tried without vga parameter and with vga=current. It can be totally related to my bios/motherboard

Please tell the motherboard / Bios version numbers as it can always be usefull as a future thread reference in case of anyone searches same exact issue

gdiazlo · 01-26-2021, 10:13 AM

You're right: Asrock TRX40 Taichi BIOS v1.73

Quote:

Originally Posted by keefaz

Please tell the motherboard / Bios version numbers as it can always be usefull as a future thread reference in case of anyone searches same exact issue