Thanks Greg! Very clear!
_______________________
Sent from MzK's phone.
On Sun, Aug 2, 2020, 14:07 Gregory P. Ennis <PoMec@xxxxxxxxx> wrote:
> Hello all--
> These instructions are somewhat OK but my messed up box is the only one
> I've got basically to help with this problem.
>
> Where can we find "correction" instructions using a "rescue" CD or flash
> drive? I understand RedHat provided detailed instructions to supported
> customers.
>
> Thanks.
>
> _______________________
> Sent from MzK's phone.
>
> ---------- Forwarded message ---------
> From: Alan McRae via CentOS <centos@xxxxxxxxxx>
> Date: Sat, Aug 1, 2020, 19:22
> Subject: 8.2.2004 Quick recovery and fix for unbootable machines
> To: CentOS mailing list <centos@xxxxxxxxxx>
>
>
> This is a quick recovery and fix for the machines rendered unbootable
> after the grub2/shim yum update.
>
> It is written for CentOS 8.2.2004 but similar should work for any CentOS
> 8 or 7 as long as you get the correct shim file,
> that is, the one from the latest installation media.
>
> I am running on an x86_64 architecture (see uname -i). Please use the
> correct shim file for your architecture (shim-<arch>-15-11.el8.<arch>.rpm)
>
> I have tested this by breaking a machine and then recovering it. It
> works for me.
>
> I hope someone finds it useful. Let me know.
>
> Regards
> Alan
>
> HOW TO BOOT AN UNBOOTABLE MACHINE
> =================================
>
> 1) Download a copy of rEFind. This is a UEFI boot manager. Burn it to a
> USB key.
>
> # wget -O refind.zip
>
> http://sourceforge.net/projects/refind/files/0.12.0/refind-flashdrive-0.12.0.zip/download
> # unzip refind.zip
> # cd refind-flashdrive-0.12.0
> # dd if=refind-flashdrive-0.12.0.img bs=4096 of=/dev/sdX (sdX is the
> device for your USB key, this will be erased, use the whole device use
> sdX not sdX1)
> 1800+0 records in
> 1800+0 records out
> 7372800 bytes (7.4 MB, 7.0 MiB) copied, 0.980893 s, 7.5 MB/s
>
> 2) Turn off secureboot in your UEFI hardware.
>
> 3) Boot the USB key. You should get a colourful screen with icons and a
> filename below.
>
> Use the left/right arrow keys to select the correct grubx64.efi.
> Hit space to boot.
>
> Your usual grub menu should appear and the system should boot normally.
>
> HOW TO FIX THE PROBLEM
> =====================
>
> 1) We need to downgrade the shim package. Now your system is running get
> an older copy of the correct shim package for your architecture
> from the CentOS installation media (e.g.
> CentOS-8.2.2004-x86_64-dvd1.iso) and install it.
>
> # mount CentOS-8.2.2004-x86_64-dvd1.iso /mnt
> # cd /mnt/BaseOS/Packages
> # cp shim-x64-15-11.el8.x86_64.rpm /root
> # cd /root
> # umount /mnt
>
> OR
>
> Get the package from a CentOS mirror:
>
> # cd /root
> # wget
>
> http://ucmirror.canterbury.ac.nz/linux/CentOS/8.2.2004/BaseOS/x86_64/os/Packages/shim-x64-15-11.el8.x86_64.rpm
>
> 2) We can now reinstall the older shim package using yum. This will
> downgrade the package to the working version.
>
> # yum install shim-x64-15-11.el8.x86_64.rpm
>
> Last metadata expiration check: 2:11:11 ago on Sun 02 Aug 2020 11:31:06
> NZST.
> Dependencies resolved.
>
>
> ===========================================================================================
>
> =========================================================================================
> Package Architecture Version
> Repository Size
>
> ===========================================================================================
>
> =========================================================================================
> Downgrading:
> shim-x64 x86_64 15-11.el8
> @commandline 647 k
>
> Transaction Summary
>
> ===========================================================================================
>
> =========================================================================================
> Downgrade 1 Package
>
> Total size: 647 k
> Is this ok [y/N]: y
> Downloading Packages:
> Running transaction check
> Transaction check succeeded.
> Running transaction test
> Transaction test succeeded.
> Running transaction
> Preparing : 1/1
> Downgrading : shim-x64-15-11.el8.x86_64 1/2
> Cleanup : shim-x64-15-13.el8.x86_64 2/2
> Verifying : shim-x64-15-11.el8.x86_64 1/2
> Verifying : shim-x64-15-13.el8.x86_64 2/2
> Installed products updated.
>
> Downgraded:
> shim-x64-15-11.el8.x86_64
>
> Complete!
>
> 3) Your system should now boot normally.
>
> 4) add "exclude=shim*" to /etc/yum.conf to prevent the broken one being
> reinstalled. You should now be able to run 'yum update'. Remove the
> exclude= when a proper fix becomes available.
>
> _______________________________________________
>
> Dear List,
>
> I have had 6 of these problems and am on my way to the office to fix two
> more.
>
> Here is what I did with an installation disc along with the advise from
> the posts of Johny
> Hughes. So far this has been easy to do and has worked every time. Make
> sure your system
> is connected to the network, and know your gateway address and a
> reasonable ip address of
> the machine for your network.
>
> #1. Boot to tine Install Disc and pick "Recovery Mode"
>
> #2. You will be given several options of recover Pick #1 to Continue
>
> #3. Use the 'chroot /mnt/sysimage' command to get into your system
>
> #4. Activate your network
>
> Find the device name you are going to use
>
> ip link
> gives you the name as in 'enp3s0' as the device
>
> ip link set dev enpo3s0 up
> activates the network card
>
> ip address add 10.0.0.67/24 dev enp3s0
> sets the card's address to 10.0.0.67 with a subnet mask of 255.255.255.0
>
> ip route add default via 10.0.0.124
> sets the gateway for your machine to 10.0.0.124
>
> #5. Make sure you have an active domain name service
>
> cd /etc/
>
> vim resolv.conf
>
> Edit the appropriate value of
> nameserver 10.0.0.124
>
> (in my case the nameserver and gateway were the same machine)
>
> #6. Use of Yum
> yum clean all
> This necessary so that you can make sure you have the latest listings
>
> yum install shim
>
> For Centos 7 you want shim-x64-15-8.el7.x86_64 which Johnny Hughes just
> released today.
>
> When this is installed you will also install mokutil-15-8.el7.x86_64
>
> #7. Exit out of recovery mode, and reboot.
>
> This has worked for me every time.
>
> Thanks to everyone's advice on this list and all the good work done by the
> Centos Team!!!!
>
> Greg Ennis
>
>
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@xxxxxxxxxx
> https://lists.centos.org/mailman/listinfo/centos
>
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