[Discuss] UEFI boot vs BIOS & Grub

[John Blomfield]

Thanks for the info. I am wading through this very comprehensive 
document http://www.rodsbooks.com/efi-bootloaders/index.html

John

On 10/02/2014 12:51 PM, brendan wrote:
> my computer came with windows8 installed with EFI enabled - it 
> requires EFI boot else it won't work (and of course, i can't just 
> reinstall it without it since i don't have actual install discs).
>
> i've ended up with grub2 installed and booting as the default 
> bootloader. there are entries for windows in grub that just point to 
> the EFI file for windows, the entry looks like:
>
> ### BEGIN /etc/grub.d/30_os-prober ###
> menuentry 'Windows Boot Manager (on /dev/sda1)' --class windows 
> --class os $menuentry_id_option 'osprober-efi-32FB-61B6' {
>         insmod part_gpt
>         insmod fat
>         set root='hd0,gpt1'
>         if [ x$feature_platform_search_hint = xy ]; then
>           search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt1 
> --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1  32FB-61B6
>         else
>           search --no-floppy --fs-uuid --set=root 32FB-61B6
>         fi
>         chainloader /EFI/Microsoft/Boot/bootmgfw.efi
> }
> set timeout_style=menu
> if [ "${timeout}" = 0 ]; then
>   set timeout=10
> fi
> ### END /etc/grub.d/30_os-prober ###
>
> the ubuntu installer managed to autoconfigure them all correctly (it 
> helps *greatly* if windows and linux are on the same physical hard 
> drive - i used to have linux on a second drive and i had a horrible 
> time of it).
>
> linux may already be mounting your EFI partition for you at /boot/efi.
>
> windows has two efi files: bootmgfw.egi (the fancy boot loader option 
> you are currently seeing) and bootx64.efi (which just boots into 
> windows) - you can choose to have one or both in your grub.cfg file.
>
> alternately, you can keep the windows boot manager loading and do some 
> junk to make it have grub/lilo as an option inside it. it didn't 
> really work so well when i tried it, however.
>
> trying to do this stuff manually is really unpleasant. if you can, 
> just let a linux installer that is EFI aware handle it (if you boot 
> the install medium via EFI boot, it should detect it's in EFI mode 
> when it starts)
>
> On 14-10-02 12:29 PM, John Blomfield wrote:
>> About 2 years ago I installed OpenSuse on a new Windows 8 Laptop, for 
>> my wife, that had EFI without much bother I just turned off the 
>> "secure boot" and proceeded. My wife's computing needs are simple so 
>> I used a fairly simple partition layout, "/" and "/home" plus a dual 
>> boot with Windows 8. By default the bootloader for OpenSuse is GRUB2. 
>> Basically, the EFI stuff was ignored and although I don't like GRUB2 
>> and prefer legacy GRUB because its some much simpler to edit the boot 
>> menu and recover from MBR being overwritten, I just left GRUB2.
>>
>> However, is seems things are changing! My new bare bones computer, 
>> although it was bought without Windows installed, is Windows ready 
>> with a very fancy GUI setup for booting either in EFI / GPT mode or 
>> "legacy" BIOS / MBR. This all points to BIOS / MBR being deprecated 
>> over time. I could of course opt for the BIOS mode and use GRUB as I 
>> always have but feel the necessity to "get up to date" as my 
>> grandkids are always telling me.
>>
>> So here is where I need help and suggestions. I have piles of 
>> documents to read on EFI boot loading but would like to know what the 
>> list is doing about all this. I read that GRUB / GRUB2 does not work 
>> well with EFI and the pure EFI bootloader does not work well with 
>> Linux. Alternatives such as ELILO, EFI stub loader and Gummiboot.  
>> Any suggestions as to where to go in all this?
>>
>> John
>>
>
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-- 
John Blomfield
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Old John B's Linux Notes http://www.oldjohnbslinux.wordpress.com