Hi Andreas,

thanks for your mail.

On Tuesday 23 February 2021 18:26:31 you wrote:
> > the plan was a dual boot install with Win10 being installed first,
> > however after several failed attempts, I scraped Win10 and went for a
> > Linux-only install.
>
> What does "failed attempts" mean here? Did Windows fail to install or
> boot? I believe that if Win 10 does not install, then there is probably a
> problem in your EFI Bios. Maybe older OS versions don't use some new EFI
> feature which is broken on your hardware?

Win10 did install as expected. I could not get devuan working either with or
without win10 residing on the same (or the secondary) ssd.

> root@zeus:/home/andi# efibootmgr -v

BootCurrent: 0012
Timeout: 5 seconds
BootOrder:
0012,000B,000A,000E,000D,0010,0013,000C,0000,0001,0002,0003,0004,0005,0006,0007,0008,0009,0011
Boot0000  Startup Menu  
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)....ISPH
Boot0001  System Information    
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0002  Bios Setup    
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0003  3rd Party Option ROM Management       
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0004  System Diagnostics    
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0005  System Diagnostics    
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0006  System Diagnostics    
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0007  System Diagnostics    
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0008  Boot Menu     
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0009  HP Recovery   
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot000A  USB:          PciRoot(0x0)/Pci(0x10,0x0)N.....YM....R,Y.....ISPH
Boot000B* devuan        
HD(1,GPT,32f56878-f016-4745-81d4-cd604cc06d83,0x800,0x100000)/File(\EFI\devuan\shimx64.efi)....ISPH
Boot000C* SanDisk SDSSDH3 500G :        BBS(HD,SanDisk SDSSDH3
500G : ,0x400)/PciRoot(0x0)/Pci(0x11,0x0)/Sata(0,0,0)......ISPH
Boot000D  USB:          BBS(65535,,0x0)/PciRoot(0x0)/Pci(0x10,0x0)......ISPH
Boot000E* hp DVDRW DU8A6SH      
PciRoot(0x0)/Pci(0x11,0x0)/Sata(1,0,0)N.....YM....R,Y..0..ISPH
Boot0010* hp DVDRW DU8A6SH :    BBS(CDROM,hp DVDRW
DU8A6SH : ,0x400)/PciRoot(0x0)/Pci(0x11,0x0)/Sata(1,0,0)...0..ISPH
Boot0011  Network Boot  
FvVol(a881d567-6cb0-4eee-8435-2e72d33e45b5)/FvFile(9d8243e8-8381-453d-aceb-c350ee7757ca)......ISPH
Boot0012* debian        
HD(1,GPT,3a69129a-ece9-4f40-bac8-afd77b951c55,0x800,0x5f000)/File(\EFI\debian\shimx64.efi)....ISPH
Boot0013* Samsung SSD 970 EVO Plus 1TB-S4EWNM0NC13957E:         BBS(HD,Samsung
SSD
970 EVO Plus
1TB-S4EWNM0NC13957E: ,0x400)/PciRoot(0x0)/Pci(0x3,0x1)/Pci(0x0,0x0)/NVMe(0x1,00-25-38-5C-01-90-30-7D)......ISPH


> root@zeus:/home/andi# lsblk -o name,partuuid,mountpoint

NAME        PARTUUID                             MOUNTPOINT
sda                                              
├─sda1      32f56878-f016-4745-81d4-cd604cc06d83 /boot/efi
├─sda2      d747b47e-d4f7-434b-858b-726b1833a191 /
├─sda3      9c21e969-e395-4a21-869e-e755fae1727f
└─sda4      ac60d0fa-fee5-4f49-9f5b-7fa5a7bdf4a1 /home
sr0                                              
nvme0n1                                          
├─nvme0n1p1 3a69129a-ece9-4f40-bac8-afd77b951c55
└─nvme0n1p2 cd28ae0c-93f6-44c1-8980-f1b445b4c74e


>
> How did you chroot into your installation? Did you bind mound
> /dev, /sys, /proc and related filesystems? Also /boot (if needed) and efi
> need to be mounted to get grub properly installed.

I did bind the mounts for proc, dev, sys prior to chroot.

Now, for some change:
I reinstalled debian to answer Ralphs question. Ironically enough, debian
recognized the installed devuan and I can now boot into devuan using the
devuan-grub-entry from debian.

I also got an off-list hint to the README which tells, that HP messed up with
the EFI-Bootloader-Discovery. Unfortunately the solution suggested in
https://dev1galaxy.org/viewtopic.php?id=15
did not work for me.

Kind regards,
Jonathan