Grub 2 os prober for windows 8

Question

I'm trying to dual boot with fedora 20 and windows 8. I install first windows and then fedora. And grub detects windows automatically.

So the default \etc\grub.d\30_os-prober for windows is this:

case ${BOOT} in chain) onstr="$(gettext_printf "(on %s)" "${DEVICE}")" cat << EOF menuentry '$(echo "${LONGNAME} $onstr" | grub_quote)' --class windows --class os \$menuentry_id_option 'osprober-chain-$(grub_get_device_id "${DEVICE}")' { EOF save_default_entry | grub_add_tab prepare_grub_to_access_device ${DEVICE} | grub_add_tab case ${LONGNAME} in Windows\ Vista*|Windows\ 7*|Windows\ Server\ 2008*) ;; *) cat << EOF drivemap -s (hd0) \${root} EOF ;; esac cat <<EOF chainloader +1 }

This creates this menuentry which doesn't boot windows:

What I've tried

I created in my /etc/grub.d/40_custom manually a menuentry which works fine

menuentry "Windows" { insmod part_gpt insmod fat insmod search_fs_uuid insmod chain search --fs-uuid --no-floppy --set=root your_UUID chainloader (${root})/efi/Microsoft/Boot/bootmgfw.efi }

So I try to adapt this for the \etc\grub.d\30_os-prober and add replace the last part with this:

cat <<EOF search --fs-uuid --no-floppy --set=root $(grub_get_device_id "${DEVICE}") chainloader (${root})/efi/Microsoft/Boot/bootmgfw.efi } EOF

but this creates:

menuentry 'Windows Boot Manager' { chainloader /EFI/Microsoft/Boot/bootmgfw.efi boot }

Which doesn't work.

My question

How should I change 30_os-prober so that it creates a working grub menuentry?

I don't know a ton about grub, but if I were you I would try changing Windows\ Vista*|Windows\ 7*|Windows\ Server\ 2008*) to Windows\ Vista*|Windows\ 7*|Windows\ Server\ 2008*|Windows\ 8*). — Alex Layton
– Alex Layton, Commented Feb 6, 2014 at 1:49
Consider using rEFInd as your bootloader. For more information on how it stacks up to grub, look here — evamvid
– evamvid, Commented Sep 5, 2017 at 3:47

Shashank Bajpai · Accepted Answer · 2014-02-11 06:54:25Z

I am not that well versed with the Fedora and its Grub2. But i will share a solution i adopted in my dual-boot system with Ubuntu and Windows XP Professional Edit grub.cfg with vim or any other editor

vim /boot/grub/grub.cfg

To:

 121 ### BEGIN /etc/grub.d/30_os-prober ### 122 menuentry "Microsoft Windows XP Professional (on /dev/sda1)" --class windows --class os { 123 insmod part_msdos 124 insmod ntfs 125 set root='(/dev/sda,msdos1)' 126 search --no-floppy --fs-uuid --set=root AC60CA8160CA522E 127 drivemap -s (hd0) ${root} 128 chainloader +1 129 }

as the Ubuntu grub default adds this Windows as the last entry. I just added this entry in front of all other menu entries.

your solution look like what I do at the moment in 30_custom, but thank you anyway :D — Sir l33tname
– Sir l33tname, Commented Feb 11, 2014 at 14:30

avtar singh · Accepted Answer · 2017-07-01 07:49:19Z

Try this :-

menuentry "WINDOWS"{ set root='(hd0,msdos1)' chainloader +1 }

Change the partition number , where your windows is installed. hd0 :- means first disk msdos1 :- means first partition.

telcoM · Accepted Answer · 2023-10-13 07:12:02Z

The /etc/grub.d/30_os-prober segment quoted in the OP generates a GRUB entry for Windows that boots in legacy BIOS-style.

But the working custom entry in the OP indicates the system uses UEFI-style. That means os-prober should be detecting Windows as a generic UEFI operating system. In other words, if you run os-prober as root, the result should be of the form

/dev/<ESP partition>@/efi/Microsoft/Boot/bootmgfw.efi:Windows Boot Manager:Windows:efi

which should trigger the efi) case in the 30_os-prober script, not the chain) case. The resulting GRUB menu entry should be similar to:

menuentry 'Windows Boot Manager (on <ESP device>)' --class windows --class os $menuentry_id_option 'osprober-efi-<ESP UUID>' { insmod part_gpt insmod fat search --no-floppy --fs-uuid --set=root <ESP UUID> chainloader /efi/Microsoft/Boot/bootmgfw.efi }

Given that the ESP is usually a FAT32 partition, the <ESP UUID> is usually just the FAT32 filesystem Volume Serial Number, of the form XXXX-XXXX instead of a real UUID.

Of course, given that the question is now almost 10 years old, it is possible that GRUB's 30_os-prober script did not include the efi) case yet at that time.

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