UEFI Explained: Windows 10 and UEFI

[Music] welcome to our advanced windows 10 lecture and we're gonna cover the an understanding of Windows 10 historically booting off firmware starting with the old basic input/output system called bias up until UEFI with CSM enabled and then finally UEFI enabled natively we're gonna look at all of those and the impact it has on Windows 10 and troubleshooting let's first understand what is firmware firmware is software code that initializes the motherboard gets all the motherboard up and running and finds the files to launch the operating system and all of that software is burned into a chip and soldered or socketed on to a motherboard now firmware has been around forever and ever in the PC world it's over 30 years old it has many limitations just because of its age it definitely needed replacing manufacturers and software developers came together and designed a new firmware called u EFI unite and extensible firmware interface it was new yes and it had all kinds of new features but there were many problems we are so pumped to have this new firmware technology but it takes time to get operating systems drivers so much of the PC ecosystem had to be changed in order to embrace this new firmware so while everybody was grappling with the new firmware that was going to be put on motherboards and all the challenges that brought in the organization that was running UEFI decided to implement what was called compatibility support module CSM and it was built-in to this new firmware and basically what it did was it gave backward compatibility so if you enable this option in UEFI it acted like that old bias so here you got a brand-new motherboard and it's got UEFI but many companies ship them with CSM enabled so if you look at the column as we look at Windows boot process and you look at the bias column brand-new motherboard with UEFI but CSM enabled boots just like the old bias only when you run UEFI in native mode do you look at the other column on the right hand side and see how Windows boots that way now remember both of these biases are UEFI let's compare you if I need if you if I was CSM enabled big difference one when we partition our hard drives they use Master Boot Record partitions and we can't use partitions any greater than 2 terabytes when we boot with ufi & CSM enable we force our CPU into 16-bit mode during the firmware session and we only have one megabyte of accessible memory because we're acting like those old biases remember the only thing that was advantage for awhile was a very fast network stack used for imaging that changed in 2019 so what about native UEFI lots of cool things we move to the GPT partition huge partitions anything above 2 terabytes is fine we run CPUs in 32-bit or 64-bit architecture no problems and if you've got 16 gigs of memory native UEFI has no problems with that it gives a secure boot we can run anti-malware prior to the operating system all kinds of features we can even boot to PCI storage Express storage and so many more I can't tell you how many times I've had a student or staff member bring me a PC or a laptop and it's got a new copy of Windows and we'll go in and check the BIOS and sure enough you if I has CSM enabled not good so how can we tell well one we can run windows and run msinfo32 and that will help us identify is UEFI in the CSM we can also look at dis properties I'll show you that in a minute and then finally you can go in your firmware and see is CSM CSM innate so if I launch msinfo32 I can look under system and under bias mode and if that shows bias then you know you've got CSM enabled if it's UEFI then you're running you if I need it under disk management I can look under the properties of my bootable disk and we'll demonstrate this in a minute and if I see that I've got my partition style is MBR and then I've got UEFI with CSM enabled this is not good if you have full native UEFI your partition will be a good partition GPT one way we can determine whether we have UEFI with CSM turned on is go to system information so I'm going to go to my search bar and I can type in sis info 32 and you can see it's popping up here with the system information desktop app let's go ahead and launch that and let me shrink this down a little bit in it in the system summary here in the system summary you can see the bias mode if yours says bias right here not UEFI bias then you know you have UEFI with CSM turned on another way is to launch control panel and I just went in the search bar and watched the desktop app control panel and I'm going to change this to small icons go to Administrative Tools and go to computer management console and I'm just going to pull this down and go to disk management I'm going to look to see the disk that boots and I can tell that by this is the partition that launches Windows even though I may have other disks listed here just zero in my case is the bootable disk and what I want to do is I want to click on this gray area disk one to zero in my case right mouse click and go to properties I'll pull this over here and I'm gonna choose the volume tab here you see partition style if you see MBR and then you know you've got UEFI with CSM turned on if you have good partition table and that's your bootable disk then you have native you if I turned on so I'm just gonna show you a couple biases and you could see where CSM is in the option of the bias this is an HP system and you can see again you can see where you can enable it or you can be UEFI native here's another one and here's another one oh man mr. Vander pol I went looked at my laptop or my PC or I looked at my family members and sure enough CSM is enabled in their UEFI BIOS am I stuck well in the past you were you had to reformat your hard drive and install Windows after you turned on UEFI native mode because the partitions on the hard drive are so different in the way that Microsoft installs Windows either in CSM mode or native UEFI well Microsoft had pity on you and they designed a tool a utility called MBR to GPT that will allow you to convert your partitions on your hard drive so that you can boot into UEFI native mode if you go to this link this website they have a video they have step by step you can convert your machine to native UEFI without the loss of data so as the utility runs it runs like this and if you look at the very bottom after it completes re redesigning the partitions you can then shutdown go to your firmware turn on native UEFI mode and voila you've booted into Windows I'm often asked what is the real difference between UEFI and the old bias in it simple as terms UEFI is now a operating system Bias was not an operating system it was a boot code UEFI is a full-blown very small but very powerful operating system this is example of a firmware chip that is socketed not burnt not soldered on to the motherboard and this is very commonly where you find your firmware so why am I wasting your time on this lecture my philosophy about troubleshooting if you're going to be a good troubleshooter you cannot troubleshoot what you don't understand so I'm walking you through this so you do understand you will be able to troubleshoot effectively when windows installs with a native UEFI enabled it partitions your disk in a very specific way first of all it creates an efi system partition it also creates microsoft creates a special partition called an MSR partition this is reserved for the boot manager so that it can understand how the rest of the hard drive is partitioned efi requires a special partition on your hard drive let's take a look at it it must be partitioned with one of the fat versions of file systems Microsoft uses fat32 there must be a folder in the root of that partition called efi Microsoft will add a subdirectory called Microsoft in addition Microsoft will add an additional subdirectory called boot and that's where it's going to put the boot manager and the BCD registry hive now how does the firmware know to find this path and this information this is put in by windows into the firmwares NVRAM when you boot up on UEFI natively you will launch boot MGR fw e fi that's the boot manager for a Windows installation on a native UEFI the BCD file is the registry hive and that will be launched by boot manager so let's let me demonstrate how to get access to our UEFI system partition you notice if I mouse over here this is our UEFI let me show how to get in there so you can actually see what we've just looked at so to do that we're gonna run the command command line CMD as an administrator and then we're going to type in these commands and X is going to be any available Drive letter so you can go to Explorer real quick check your machine and look at your Drive letters I am using C and D so I can use anything but C and D for X so I'm going to type in CMD and I'm going to right mouse click and run as administrator and I'm going to I like to copy and paste text so I'm going to choose I'm going to modify this to Z because I don't have a Z drive letter used and I'm simply going to select all this copy and come up to my editor my command line and right up here I'm going to go to edit and I'm going to choose a paste and it pops it right in to the command line and then I'm in hit enter now I'm going to change my drive letter to Z Z C colon do a dir so you can see that I'm in the partition I asked it to mount that partition with the drive letter Z and when I do a dir you can see our directory efi remember that is absolutely must be there for all UEFI native boot we're going to explore a little bit I'm going to change directory to the efi folder and do a dir and there we see our Microsoft subdirectory so if I change to Microsoft and I do addy you can see we've got the various folders and subfolders required for our boot system I'm going to change to boot a boot subdirectory do a dir there's our BCD that's our registry key and there is our boot manager boot manager FW efi so there is the file the boot manager file that launches everything that what that's what actually launches Windows and the first thing that it does is it comes up and reads this registry key and that's what starts getting everything really rocking and rolling alright remember you cannot troubleshoot what you don't understand let's review this one more time the firmware chip is initialized when you hit the power button the motherboard then is starting to be initialized by the software on that chip hardware's initialize motherboard is initialized post is ran efi drivers are launched it then starts discovering devices and discs it will scan for a drive with the EPS partition it will then look for in that partition the efi folder it pulls path and file information from the UEFI NVRAM it will find the microsoft boot folder launches boot manager boot manager then we'll load BCD and BCD will help it discover and launch the win loader efi remember the boot process with native UEFI and UEFI with CSM enabled is very different if you'd like a little bit more detailed information about the process you can pause the video and take a look at this diagram now that you have finished watching this lecture on how this works if you'd like to learn how to troubleshoot that you can go to my channel and just search and you can search for video 1 advanced troubleshooting and you'll get this video right here that will walk you through the boot how to troubleshoot how to solve problems in this area [Music] [Music]

Channel: TechsavvyProductions

Views: 33,805

Rating: 4.9396434 out of 5

Keywords: UEFI and CSM, CSM, Windows 10, UEFI, firmware, Windows Troubleshooting, bootmgfw.efi, winload.efi, GPT partitions, MBR2GPT.exe

Id: G_qKrJPuAmg

Length: 15min 40sec (940 seconds)

Published: Fri May 10 2019