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efibootmgr -b 6 -B
Skipping unreadable variable "Boot0006": Input/output error
Could not delete variable: Input/output error
Some background. I installed a new system board, cpu, ram, and kept my two spinning rust drives, and 1 256 gig SSD drive. Each drive was bootable on the old BIOS system. I did not convert anything to GPT partitioning. EFI BIOS has CSM ( comparability mode ) set. I could boot off all three drives.
I was happy with new system. I bought a 1 tera byte NVME drive, and installed it. I installed current on it, using Live Slackware iso. That worked great.
I had a need for a drive elsewhere, and was not going to use the 500 gig disk, so I removed it. It was re-formatted and installed in another device.
So, now I have 1 spinning rust drive with current ( not GPT ) , one 256 Gig drive with Slackware 14.2, ( not GPT ) and one NVME drive with current. All three boot, this was a bit of a surprise to me, since I have one drive that will only work in UEFI mode, and two that need CSM mode to function.
When Slack 15 is released, I would like to remove the spinning rust drive, ( just not needed ) and reformat the 256 gig drive to GPT and install 15.
So, I decided it was time I learned something about UEFI. I have looked on this forum, there are a ton of posts on UEFI, I have not found out how to remove the stale entry, that I'm thinking was caused by my removing the 500 gig drive.
When I proceed with removing the one drive, and reformatting the SSD, how do I change these boot entries? How do I fix the error I have now?
I get an I/O error when trying to delete Boot0006 with efibootmgr
efibootmgr --help shows the arguments for quick reference. -A makes an entry inactive and -o lets you move the offending entry last (you set the order manually). I generally type in all the numbers (e.g. "0006") as a habit, but that may be irrelevant to the problem you're having.
With that said, I was spending some time with the current covid-19 restrictions to fix up and issues I have, even though they are not causing immidate problems. Part of this exercise is to learn something about UEFI. I avoided it like the plague for close to 10 years. It won't go away, ( just like pulse audio ) so I thought it was time to learn how to live with it.
Much of my concern is the other two disks that are not GPT, and removing and or repartitioning them. I want to know how to deal with UEFI and the boot entries in NVRAM.
I'm not thrilled that I followed the man page for efibootmgr to remove an entry, it fails.
So, the tool we are supposed to use doesn't work as advertised. Now what else won't work?
As you can see, Boot0006 does not show, B0009 does, I'm sure it will not if I use the -o command.
I have done a lot of reading, one thing I saw, was to remove the invalid entries by going into the BIOS, and loading the "Default settings". Failing that, remove all power, remove the cmos battery, press the power button for a few seconds; to ensure the power is all drained, put the battery back in, and boot to BIOS mode and set "Default" settings.
I'm still contemplating if I want to go that far.
I have also looked into a BIOS update. Once again, there is risk involved. Not sure this will buy me anything.
I realise this post is a bit old, but I stumbled across this trying to fix my own issues (entries in nvram not showing in boot menu). I'm assuming you used sudo? I got an error when I tried to remove a boot entry, but I forgot to use sudo. Once I did, I was able make changes. You're stuck in read only mode unless using root or sudo.
Slackware comes without forcing the user to use sudo. I su- to the root user, as most Slackers do. I have enabled the use of sudo on one system do to some issues wrapped around systemd.
You do need elevated privledge to make changes to NVRAM, either root or sudo to root.
Quite the resurrection of an old thread by Keys_73. Did you ever get the corrupt boot entry sorted? Personally in this situation I would've done an NVRAM reset (or run something like CleanNvram.efi from opencore's package) and set up boot entries from scratch.
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