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Is it possible to having installed Windows 10 and Ubuntu reformat 100MB Efi partition and 2MB BIOS boot partition to make everything grub/efi work? Also is it possible to remove or see the content of /dev/sda where is grub installed? I have such situation, have all partitions with installed Windows and Ubuntu + Windows recovery and Windows restore partitions but bios stopped to see the hard drive in bios boot options (It detects the hard drive as hardware with all model info, etc) and only see in boot options DVD and aditional USB if attached.

I have all set on Efi boot partition and have issues with make it work so addidtionally created 2 MB of legacy BIOS boot partition but not sure what should be placed there? Grub2 i386 image? So...there is grub installed on /dev/sda, Efi partition with efi grub and boot/windows/ubuntu efi files and bios boot partition empty...what can I do to try to make the bios see again hard drive filesystem to choose or just boot options based on hard drive? grub.cfg seems to be properly configured

PawełG
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  • How you boot install media UEFI or BIOS/CSM is then how it installs. And you do not specify use of ESP - efi system partition as it is automatically used with UEFI install. Or if BIOS/CSM install the bios_grub partition is used. The bios_grub only used with BIOS installs is unformatted and shown as an error in gparted (as it has no format). What brand/model system. You must use 64 bit installer if UEFI system. https://help.ubuntu.com/community/UEFI & http://askubuntu.com/questions/221835/installing-ubuntu-on-a-pre-installed-windows-10-with-uefi – oldfred Mar 04 '18 at 17:11
  • I've managed to start installed Ubuntu on hard drive by starting liveUSB session -> when grub menu appears i press 'c' to get into grub prompt-> set root=(partition with installed ubuntu), set prefix=(partition with installed ubuntu) /boot/grub, insmod normal, normal ('enter' after each) -> I get proper grub menu with Windows and Ubuntu but only section 'advanced Ubuntu settings' and from there pressing latest linux kernel 4.13.36 generic starts the system properly...so, it seems it's fine but after reboot again all procedure to be done...no bootable options in bios other than DVD and USB – PawełG Mar 04 '18 at 17:45
  • What brand/model system? Can you try booting from UEFI menu with flash drive removed? – oldfred Mar 04 '18 at 20:13
  • Asus X750JB, I cannot boot without USB or DVD live Ubuntu or Windows, may start only linux installed distro via grub prompt, have no idea how to do it with Windows. Thinking about erase whole disk and create new partition table or send laptop to after guarantee meintenance... – PawełG Mar 05 '18 at 07:03
  • oh, and I probably can boot only in uefi mode (but strong maybe here), in other mode even when liveusb is plugged it shows 'please attach another boot device' or something similar like boot partition not found. It just lost some info between bios and hard disk (MBR issue?)...I've used boot-repair without any effects and Rescatux which messed all this, due to Rescatux use I've lost HDD boot options in bios trying all available options this program offers. – PawełG Mar 05 '18 at 07:04
  • this is output after installing new kernel 4.15.7 in installed Ubuntu 17.10.1: generating grub menu: found all linux images, found Windows Boot Manager on /dev/sda1@/EFI/Microsoft/Boot/bootmgfw.efi, adding boot menu entry fro EFI firmware configuration, all done without errors...of course after reboot I have same issue in bios, no connection between data and no hdd boot options vesible for bios – PawełG Mar 05 '18 at 07:29
  • I've got this from boot-repair summary: Grub2 (v1.99-2.00) is installed in the MBR of /dev/sda and looks at sector 1501497344 of the same hard drive for core.img, but core.img can not be found at this location. – PawełG Mar 05 '18 at 12:39
  • http://paste.ubuntu.com/p/J3vtdgn4Wf/ – PawełG Mar 05 '18 at 13:22
  • At some point you also installed in BIOS boot mode to put grub into the gpt protective MBR and created the bios_grub partition. That would be for BIOS boot on gpt drive. But your system has /EFI/ubuntu for UEFI boot and is configured for UEFI boot. Some Asus models have needed UEFI update. Some systems need work arounds: http://askubuntu.com/questions/486752/dual-boot-win-8-ubuntu-loads-only-win/486789#486789 Boot-Repair should automatically do copy file with 'use standard EFI file': http://askubuntu.com/questions/582073/dual-boot-but-only-windows-boots/582114#582114 – oldfred Mar 05 '18 at 14:17
  • I'll try to follow Your suggestions but the thing is that even running liveUSB rEFInd it doesn't detect any system installed on /sda or /sdax like it doesn't see hard drive still. Currently BIOS boot partition is empty unallocated, I'll install there core.img from grub install -target=i386...maybe it's about standard booting which works (non efi)? It's all in all a mess to get used to all this thing for me really, before efi it was way easier and I remember when grub packages were installed there wasn't any efi but rather standard. I may be wrong but that's what I remember was rather in use. – PawełG Mar 05 '18 at 16:13
  • You do not do anything with core.img. You always install grub to drive like sda whether UEFI or BIOS. And then if UEFI it adds its boot files to ESP or if BIOS adds core.img to correct place. With gpt drive then you have to have the bios_grub for core.img, but that partition is unformatted and just space on drive for core.img. With BIOS core.img is in the sectors just after MBR, but that space does not exist with gpt. – oldfred Mar 05 '18 at 16:38
  • right, so....is this core.img not found in MBR needed to be reinstalled there to be found or it's not the case? it doesn't matter and I should only focus on /sda1 ESP partition? – PawełG Mar 06 '18 at 04:41
  • Only if you really want Ubuntu in BIOS boot do you have anything in MBR. And with UEFI anything in gpt's protective MBR is ignored. Or just fix UEFI issues. If Windows is UEFI, you generally want Ubuntu in UEFI boot mode. – oldfred Mar 06 '18 at 15:02

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