CentOS - Feb 2018 - Re-enable grub boot in UEFI (Windows took over it)

Hello there,


Dell XPS-15-9560 laptop (SSD drive, UEFI, secure boot off).. Windows 10
pre-installed, CentOS7 installed in a separate partition and running
for months w/o issue. Don't know what happened but at reboot yesterday
(not even booted in Windows, just rebooted), grub has disappeared,
booted in Windows by default, which apparently has taken over the UEFI
boot.

By booting from a USB drive w/ CentOS7 LiveGnome, I could use its grub
command prompt to inspect the UEFI of the local SSD drive, see that the
centos/ sub-directory and files are still there.

/boot/efi/EFI/centos/:
BOOT.CSV
BOOTX64.CSV
fonts
grub.cfg
grub.cfg.1501243846.rpmsave
grub.cfg.1505469290.rpmsave
grubenv
grubx64.efi
mmx64.efi
shim.efi
shimx64-centos.efi
shimx64.efi

maybe /boot/efi/EFI/Boot/ contents has been altered?

/boot/efi/EFI/Boot/:
bootx64.efi
fbx64.efi

I had a backup of the full efi partition (`dd`) but it's outdated and
I feel it's a bad idea to restore the partition from it.

Still from this "external" grub prompt, I could boot into my CentOS7
using:
 configfile (hd0,gpt1)/EFI/centos/grub.cfg

At least I know how to get back to it :-).

But now, how could I give the UEFI control back to grub? Is there a
grub2 or grubby command I can run to make grub the default? I've read a
lot and still cannot figure out exactly what to do or don't dare
running commands that could make things worse.

And I have the feeling the at next Windows boot, I may need to do it
again..


Regards,

-- 
wwp
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You can to use efibootmgr for this. NVRAM boot entry is what changed, not
the contents of the EFI System partition.

efibootmgr -v

Will list all entries and Boot Order. You need to use --bootorder to make
sure the CentOS entry is first.


Chris Murphy

Hello Chris,


On Thu, 01 Feb 2018 17:00:03 +0000 Chris Murphy <lists at
colorremedies.com> wrote:
> You can to use efibootmgr for this. NVRAM boot entry is what changed, not
> the contents of the EFI System partition.
> 
> efibootmgr -v
> 
> Will list all entries and Boot Order. You need to use --bootorder to make
> sure the CentOS entry is first.
Interesting.. thanks for your reply!

Too bad I never run this command when things were OK (in order to
compare), 'cause now, what it says doesn't mention anything that seem
related to the CentOS partition or I read wrong:

BootCurrent: 0007
Timeout: 0 seconds
BootOrder: 0001,0002,0003,0004,0005,0006,0007
Boot0000* Windows Boot Manager 
HD(1,GPT,a6b87338-9b9c-4a50-8fde-2447e8fdebb6,0x800,0xfa000)/File(\EFI\Microsoft\Boot\bootmgfw.efi)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}....................
Boot0001* UEFI: A400 NVMe SanDisk 512GB, Partition 1   
HD(1,GPT,a6b87338-9b9c-4a50-8fde-2447e8fdebb6,0x800,0xfa000)/File(EFI\Microsoft\Boot\bootmgfw.efi)..BO
Boot0002* Diskette Drive        BBS(Floppy,Diskette Drive,0x0)..BO
Boot0003* M.2 PCIe SSD  BBS(HD,P0: A400 NVMe SanDisk 512GB,0x0)..BO
Boot0004* USB Storage Device    BBS(USB,KingstonDataTraveler 3.0PMAP,0x0)..BO
Boot0005* CD/DVD/CD-RW Drive    BBS(CDROM,CD/DVD/CD-RW Drive,0x0)..BO
Boot0006* Onboard NIC   BBS(Network,Onboard NIC,0x0)..BO
Boot0007* UEFI: KingstonDataTraveler 3.0PMAP, Partition 1      
PciRoot(0x0)/Pci(0x14,0x0)/USB(16,0)/HD(1,MBR,0x61f11812,0x800,0x737f800)..BO

I don't know what 0001 and 0002 refer to exactly (there's only one SSD
drive in this laptop).


Regards,

-- 
wwp
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On 02/01/2018 12:15 PM, wwp wrote:
> Hello there,
> 
> 
> Dell XPS-15-9560 laptop (SSD drive, UEFI, secure boot off).. Windows 10
> pre-installed, CentOS7 installed in a separate partition and running
> for months w/o issue. Don't know what happened but at reboot yesterday
> (not even booted in Windows, just rebooted), grub has disappeared,
> booted in Windows by default, which apparently has taken over the UEFI
> boot.

The DELL XPS-13-9360 in its BIOS has an option (named "auto boot
recovery" or similar - sorry the machine is somewhere else) that is by
default enabled. I guess you have it enabled as well.

This option is triggered by two unsuccessful boot trials, and leads to
the loss of the grub menu, and restoration of the (non-grub) "Windows
boot manager" (or whatever it's called).

After being bit by it once, I disabled it.

HTH,

Kay

P.S. I recovered my Ubuntu grub menu by booting from the Ubuntu live
USB, and then
sudo su
mount /dev/nvme0n1p7 /mnt
cd /mnt
mount /dev/nvme0n1p1 boot/efi
mount --bind /proc proc
mount --bind /sys sys
mount --bind /dev dev
chroot /mnt
grub-install /dev/nvme0n1
update-grub

On CentOS, the last two lines would be

grub2-install  /dev/nvme0n1
grub2-mkconfig -o etc/grub2.cfg

> 
> By booting from a USB drive w/ CentOS7 LiveGnome, I could use its grub
> command prompt to inspect the UEFI of the local SSD drive, see that the
> centos/ sub-directory and files are still there.
> 
> /boot/efi/EFI/centos/:
> BOOT.CSV
> BOOTX64.CSV
> fonts
> grub.cfg
> grub.cfg.1501243846.rpmsave
> grub.cfg.1505469290.rpmsave
> grubenv
> grubx64.efi
> mmx64.efi
> shim.efi
> shimx64-centos.efi
> shimx64.efi
> 
> maybe /boot/efi/EFI/Boot/ contents has been altered?
> 
> /boot/efi/EFI/Boot/:
> bootx64.efi
> fbx64.efi
> 
> I had a backup of the full efi partition (`dd`) but it's outdated and
> I feel it's a bad idea to restore the partition from it.
> 
> Still from this "external" grub prompt, I could boot into my
CentOS7
> using:
>  configfile (hd0,gpt1)/EFI/centos/grub.cfg
> 
> At least I know how to get back to it :-).
> 
> But now, how could I give the UEFI control back to grub? Is there a
> grub2 or grubby command I can run to make grub the default? I've read a
> lot and still cannot figure out exactly what to do or don't dare
> running commands that could make things worse.
> 
> And I have the feeling the at next Windows boot, I may need to do it
> again..
> 
> 
> Regards,
> 
> 
> 
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
>

On Mon, Feb 5, 2018 at 8:27 AM, Kay Diederichs
<kay.diederichs at uni-konstanz.de> wrote:
> grub-install /dev/nvme0n1

Running this on computers with UEFI firmware is not good advice, it's
an obsolete command. People should use the prebaked grubx64.efi binary
that comes in the grub2-efi package, and is a signed binary so it can
support UEFI Secure Boot.

If you run grub2-install, a new unsigned grub binary is created,
replacing grubx64.efi. If you have Secure Boot enabled, you will not
be able to boot, until you either reinstall the grub2-efi package (or
you self-sign the grub2-install created binary and then go through the
process of informing the firmware this is a valid binary by using
mokutil - but I estimate maybe 1 in 50 people might do this).




-- 
Chris Murphy

Hello Kay,


On Mon, 5 Feb 2018 16:27:19 +0100 Kay Diederichs <kay.diederichs at
uni-konstanz.de> wrote:
> On 02/01/2018 12:15 PM, wwp wrote:
> > Hello there,
> > 
> > 
> > Dell XPS-15-9560 laptop (SSD drive, UEFI, secure boot off).. Windows
10
> > pre-installed, CentOS7 installed in a separate partition and running
> > for months w/o issue. Don't know what happened but at reboot
yesterday
> > (not even booted in Windows, just rebooted), grub has disappeared,
> > booted in Windows by default, which apparently has taken over the UEFI
> > boot.  
> 
> 
> The DELL XPS-13-9360 in its BIOS has an option (named "auto boot
> recovery" or similar - sorry the machine is somewhere else) that is by
> default enabled. I guess you have it enabled as well.
> 
> This option is triggered by two unsuccessful boot trials, and leads to
> the loss of the grub menu, and restoration of the (non-grub) "Windows
> boot manager" (or whatever it's called).
> 
> After being bit by it once, I disabled it.
At last I could reboot the system, and could verify that, you're right,
there's a Bios option to restore factory settings in case of a (more or
less) parametrable amount of boot failures. I disabled it as well, this
is way too dangerous in case of booting from USB flashdrives (for
instance) and can be enabled back if it's really needed. Thanks!


Regards,

-- 
wwp
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