Linux Internals: UEFI Boot Stages using Debian 11 

I found your channel about a month ago, DJ, and I appreciate you more than I can adequately convey in words. A lot of content on these sorts of topics are either deeply technical and specific tutorial style slideshows or else over-simplified and hand-wavey "science communicator" videos designed for interested people who will never use the info. You do a great job of bridging that divide and delivering these tightly-focused presentations that don't dumb things down but also don't get bogged down in details.

I gained a lot of insight from this explanation. Have more tolerance for UEFI now. Thanks.

I finally cleared up my confusion with UEFI and GPT by reading the documentation written by Rod Smith, the maintainer of refind and also (I believe) gdisk. His docs are a bit old now but still relevant and well written - he's a technical writer. I also read the Wikipedia pages for UEFI and GPT. After studying these docs, I finally abandoned the legacy boot (often called CSM - Compatibility Support Mode) + MBR and use UEFI + GPT exclusively. BTW, I thought ESP stood for EFI System Partition. The standard says that it must be formatted with a fat32 filesystem, which I don't recall you saying.

Thanks. As always, this was most insightful.

Great video! you gave so much information to look into

Quite a good overview, thank you for this DJ.

Awesome content - thank you very much! I always want to learn more and dive deeper. There are not many people that really know how these things work. Educators, when you question them about these thing just explain it as a magical black box, and they don't like that that explanation is not enough for those of us who have a innate need to know..

very enlightening, thanks so much!

Thank you sir. I just learnt about systemd-analyze existence because of you :) now I have my hands scratching

Great video. Loved it

The best talk on the boot process I've heard for years. I also laughed at the reference to Microsoft's file partitioning as designed by a committee. That is how a camel came about - the committee was trying to design a type of horse!

this helped me so much. thank you

Thanks DJ

Still actual 99% , I believe . Enjoyed your talk !

Thanks

Very interesting topic.👍🏻 Do you have any experience with setting up secure boot on a linux installation yourself and if so, do you think it is worth the hassle for a personal/home installation?

gdisk -l /dev/sdx will provide the same info as fdisk -l, but only for the one device at a time. I have had a few distros come with a direct kernel-stub boot option, where UEFI directly loads part of the kernel skipping the boot loader entirely. It is a bit faster, but because I don't frequently reboot I still prefer the bootloader method for the option of specific kernel versions and modifying the boot parameters. It also seemed to have fewer issues with dualbooting debian and windows7, compared to using the UEFI menu to select the operating system; this was 8+ years ago and I've had no compelling reason to do a fresh bare metal setup since then. (Especially as I would need to buy win11 for my once per year need of Windows compatible software.) It's possible to have both stub and bootloader methods as options in the UEFI boot-options menu.( f2 on my computer) Somewhat similar to a grub menu with multiple operating systems. (Significant overlap and redundancy with GRUB and UEFI)

According to the disclaimer, I'm eager to see an update in a month. Would you also cover other distros as well?

20:12 - not a big deal if you retain its GUID or disable WinRE, move/delete/create partition and enable WinRE again (REAgentC command). In fact you don't even need a separate WinRE partition because it can sit on the same volume with \Windows directory. 899 MiB partition you have is located just AFTER "Windows" basic data partition on purpose - because winre.wim image is larger in newer editions so for example (real life situation) - you have Windows8.1 (with 450 MiB WinRE part. at the beginning of the disk) and upgraded in place to W10/11 - now new winre.wim can't fit into this WinRE because partition is too small. So you end up with two WinRE partitions (first useless and second working). Another important thing with this behaviour - Windows can easily shrink or extend NTFS volume from its end in on-line mode.

👍👍

I am reaching userspace in 1min 3.664s and graphical.target after after 54.042s. I don't know if it takes so long because I have the non-free debian (bullseye) version or it is a 10 years old beaten down low spec office computer.

Swap partition and no side alignment?

Interesting video because I just had a problem related to UEFI on Debian 11 installs. In particular, I decided to replace one of my Fedora 35 installations with Debian 11 (to hedge my bets, so to speak). I used the graphical installer with the non-free net install iso. I decided to make it all fresh, and the disk partitioning step set the default UEFI partition to size 512 with boot flag set. After installation my boot attempts failed with a "can't find bootable media" message. I started a live Linux Mint session from usb and ran their boot repair program. It gave an error message that the partition size did not match the block size of 2048 but said a repair was made successfully. After this Debian booted just fine. Should I have set the UEFI partition to a size of 2048 during installation, or is this an installer bug of some sort? The SSD was a brand new Western Digital.

Is there an update?

Many motherboards of LGA1155 (Sandy Bridge and Ivy Bridge processors) do not support UEFI bios. Installing modern versions on Linux on them is becoming a pain, because Linux is supposedly to have better supports on older devices.

I don't see how anyone can tolerate windows. Officially it must be on for hours to update correctly and it seems, too frequently when I wish to do something urgent, it needs 15 minutes to update. But for security reasons I do not leave my network on when not in use. DJ combines technical expertise with historical scholarship. I could listen to him for hours (while win is updating LOL!). Will be shutting down remaining windows PC's forever soon.

I don't get why people get so obsessed with boot time.. I start my pc maybe 3 times a week the rest it's in suspend to ram

i left linux... all distros are slow, with lagg or low performance, except UBUNTU, ubuntu is faster smoothy and good, my pc is i3 10th 8 gb and nvidia; i go back windows 10 :/ ... i hope OSTree will better in a future