Dual-boot with Win8 on UEFI

Havin_it · Posted: Thu Jun 20, 2013 3:30 pm Post subject: Dual-boot with Win8 on UEFI

Hi,

So my trusty NC10 blew up

and I've replaced it with a HP DM1 which comes with Win8 and, of course, UEFI. It does have a legacy mode, but I'd like to make my Gentoo install fully EFI anyway if possible. I've gotten as far as turning off Secure Boot (ptooey!) and booting into a SystemRescueCD USB key with added rEFInd to boot in EFI mode, and have done my partitining... or have I?

I just realised I'd need an EFI boot partition, but of course there already is one (for Windows). Inside, it contains a /boot/EFI folder with various sublevels (/HP, /Microsoft etc) that contain further /EFI folders and *.efi files. The partition is 200MB with about 60MB used.

My initial question here is, should I place linux EFI files in there too, or will Windows get "upset" about this? If it's OK, is the existing space likely to be sufficient (both for whatever I add with grub2 and whatever HP or MS in their wisdom may add later) or should I enlarge it, and to what size?

I'm reading as much as I can about this but haven't found a parallel case study yet, so any advice would be very welcome.

py-ro · Veteran Joined: 24 Sep 2002 Posts: 1734 Location: Velbert

You can just add your Bootloader files, no problem.

You can also use an additional boot-Partition to store Kernel-Images, if you use a bootloader to chainload Linux.

Bye
Py

srs5694 · Posted: Thu Jun 20, 2013 4:35 pm Post subject:

The partition you identify is known as an EFI System Partition (ESP). Why some tools refer to it by another name is beyond me; that just creates confusion. In any event, the ESP is intended to hold EFI-specific files, and as a practical matter, that means that all OSes installed on the computer must be able to access it, so as to store their boot loaders and related files.

In Linux, the ESP is traditionally mounted at /boot/efi and holds a Linux boot loader like ELILO or GRUB 2. Some configurations also place the Linux kernel and initrd file (if used) on the ESP. If you do that, a larger ESP may be in order. Also, some users have reported problems (apparently caused by EFI bugs) when a FAT32 ESP is smaller than 512MiB. Overall, I'd say to leave it sized as it is unless you run into problems with files seeming to disappear or if you store enough kernels on the ESP for 200MiB to become cramped.

Since you say you're using rEFInd, you should be aware that rEFInd comes with drivers for ext2/3fs, ext4fs, and ReiserFS. If you store your kernel on any of these filesystems, rEFInd can launch the kernel from its native filesystem. If not, you may want to copy your kernel to the ESP. This is a bit easier if you mount your ESP at /boot, since then the traditional location for the kernel is on the ESP. This is a bit unconventional, but it can work well.

If you're chainloading from rEFInd to ELILO, GRUB Legacy, or GRUB 2, then you'll need to pay attention to the boot loader's requirements. ELILO works best with the kernel on its own partition, but GRUB Legacy and GRUB 2 can both read other filesystems. IMHO, though, using one of these boot loaders with rEFInd just complicates matters, at least in most cases. (There are some odd bugs that can be worked around by such configurations, though; or you may need a unique feature of GRUB 2.)

Havin_it · Posted: Thu Jun 20, 2013 8:27 pm Post subject:

Hi, thanks both for the replies

Sorry, rEFInd is sort of a red herring: I'm not intending to use it in the final setup, just used it to make the SRCD liveusb bootable in EFI mode.

Really I prefer the setup to have as few moving parts as possible: in fact, though I haven't quite got my head around this part, I just read that the kernel itself (appropriately configured) can be booted "directly" by EFI - does this in fact mean somehow that I don't even need GRUB2?

I usually keep just one old kernel besides the active one, so I reckon this should be OK to put in the ESP (especially if there is nothing else needing to be added there?).

srs5694 · Posted: Fri Jun 21, 2013 1:24 am Post subject:

Havin_it · Posted: Sat Jun 22, 2013 12:42 pm Post subject:

Heh, you make a very good point there: dual-booting a bit tricky without a menu :roll:

So GRUB2 it is. However I don't seem to be getting installation right. Following the Wiki page, I've put the kernel in /boot, mounted the ESP at /boot/efi and run the following in the chroot:

Logicien · Posted: Sat Jun 22, 2013 1:15 pm Post subject:

I had the same problem. After installing Grub2 in UEFI mode, Windows Seven was continuing to boot automatically at the next reboot. I haven't found any way to make the UEFI firmware boot directly Grub and then choose the OS I want including Windows. I had to press the UEFI boot device key to select Grub and have his menu.

It's look like the Windows UEFI bootloader is always the default for the UEFI firmware when Windows is install in UEFI mode. I tried to change the boot order with efibootmgr and the EFI shell and put the Grub EFI file in the default or boot directory of the EFI System Partition, without success.

I tried some other hacks too in the EFI System Partition, but then Windows refused to boot. Possible reason, only the EFI firmware can boot Windows EFI because of the secure boot.

So, because I did'nt want to press the UEFI boot device key at any boot to select a bootloader, I just remove Windows that I did'nt really need and his directories in the EFI System Partition and than I have been able to make Grub appearing automatically at boot up.

It could be interesting to know if there's a way to allow an other bootloader than the Windows one be the default when Windows is install in UEFI mode. If not, Grub EFI must be load from the Windows boot menu if possible to advoid the need to press the UEFI boot device key.

I think the futur will less compliant to a dual boot with Windows if the EFI mode become generalised. I keep interested in Coreboot.
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Paul

ulenrich · Veteran Joined: 10 Oct 2010 Posts: 1480

ppurka · Advocate Joined: 26 Dec 2004 Posts: 3256

I followed this guide:
http://xtothei.wordpress.com/2012/05/08/gentoo-uefi/
from Step 4 onwards. This guide uses Grub2 and I found the directions very clear. In my configuration, I don't have a separate /boot partition. I do mount /dev/sda1 to /boot/efi. I also used ~amd64 grub2 and not the live version.
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Havin_it · Posted: Sat Jun 22, 2013 5:00 pm Post subject:

OK, well I have now got as far as booting Gentoo from the HD, although I needed to go through rEFInd to do it

rEFInd (on my USB stick) detected the Gentoo loader fine, and showed it in its menu, which put me through to GRUB and a straightforward boot. I've since discovered the boot-order menu at F9 on startup that also lets me boot gentoo, but this doesn't seem to be editable from within the the machine's setup screens. (And no, it's not appearing in the Windows boot manager either.) At least I know my install is otherwise good.

@ulenrich, I just looked and your hunch is correct:

[ESP]/EFI/Boot/bootx64.efi

is the same file as

[ESP]/EFI/Microsoft/Boot/bootmgfw.efi

So when I'm able to reboot next I'll try replacing it with

[ESP]/EFI/gentoo/bootx64.efi

The only other thing that's occurred is using efibootmgr, which I presume must have been invoked by grub to get the "gentoo" item into the menu to begin with. Currently it shows this:

DONAHUE · Posted: Sat Jun 22, 2013 6:45 pm Post subject:

booted in windows:

Download and extract rEFInd from:
http://sourceforge.net/projects/refind/files/0.6.12/refind-bin-0.6.12.zip/download

Install rEFInd from windows as described at
http://www.rodsbooks.com/refind/installing.html#windows

reboot

no grubs, no copying kernels to esp's, only the windows ESP, multiboot menu, add more efi stub configured kernels on gpt disks in ext2/3/4fs, hfs, or reiserfs file systems and refind finds them and adds them to the menu ...
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ulenrich · Veteran Joined: 10 Oct 2010 Posts: 1480

srs5694 · Posted: Sun Jun 23, 2013 1:51 am Post subject:

DONAHUE · Posted: Sun Jun 23, 2013 5:02 am Post subject:

http://wiki.gentoo.org/wiki/UEFI_Dual_boot_with_Windows_7/8 long winded and tedious exposition of what worked on a hard case resistant asrock board with ami hybrid bios implementing a stripped down aptio uefi.
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Havin_it · Posted: Sun Jun 23, 2013 12:44 pm Post subject:

@srs5694, some of your points were discussed above, but thanks for the expansive post anyhoo

Sure enough, replacing the bootx64.efi made no difference, and efibootmgr -v shows why (was posted above, but here it is when booted without the aid of the USB stick, FWIW):

srs5694 · Posted: Sun Jun 23, 2013 11:40 pm Post subject:

Havin_it · Posted: Tue Jun 25, 2013 11:54 am Post subject:

Looks like it is indeed "selective amnesia". I plucked up courage and changed the BootOrder using efibootmgr, but on reboot the order reverted to put Win8 first again. So far there are two approaches that work:

Issue an automated call to efibootmgr on every boot, to set BootNext to the gentoo entry. Bit scissors-and-tape, but effective.
Overwrite /EFI/Microsoft/Boot/bootmgfw.efi with the GRUB loader. Not sure how I'll be able to boot Windows now though :S

srs5694 · Posted: Tue Jun 25, 2013 3:46 pm Post subject:

Havin_it · Posted: Fri Jun 28, 2013 1:05 pm Post subject:

OK, well I'm going with the approach of moving the Win8 loader one level up, but this still leaves me unable to boot Win8.

@srs5694, I tried using your custom menuentry above:

ulenrich · Veteran Joined: 10 Oct 2010 Posts: 1480

Havin_it · Posted: Fri Jun 28, 2013 2:54 pm Post subject:

srs5694 · Posted: Fri Jun 28, 2013 4:13 pm Post subject:

The "invalid cluster" error sounds like a filesystem error to me. In fact, I think I found it in the source code:

https://github.com/jolicloud/grub2/blob/master/fs/fat.c

(Search on "invalid cluster" for the context.) If I'm right, then you should umount the ESP and run dosfsck on it from Linux, or use CHKDSK in Windows. If that fails, try backing up the entire ESP, re-creating it with mkdosfs, and restoring all its files. (This may also require you to update your /etc/fstab, if you mount it via its "UUID.")

Havin_it · Posted: Fri Jun 28, 2013 7:53 pm Post subject:

Good spot, thanks

I dunno how I managed to corrupt it, I've been very gentle with it so far :roll:

That got it working. However, more weirdness! After booting into Win8 and rebooting from there (which took a suspiciously long time), I got booted back into Win8. On inspecting the ESP contents, I discovered that the /EFI/Microsoft/Boot/bootmgfw.efi (which I'd overwritten with GRUB's loader) had been overwritten again.

As if that weren't odd enough, the "new" bootmgfw.efi is *not* the same file as the original (different md5sum). Where did it come from? WTH are HP up to?

srs5694 · Posted: Fri Jun 28, 2013 10:45 pm Post subject:

Have you tried "bcdedit" in Windows? I mentioned it earlier, but I don't see any explicit mention that you've tried it. The command, typed from a Windows Administrator Command Prompt window, would be:

Havin_it · Posted: Sat Jun 29, 2013 1:47 am Post subject: