[SOLVED] Preparing to upgrade from BIOS to UEFI

dracolich · 03-06-2016, 12:21 PM

I have been dual booting with Windows 7 and Slackware 14.1 for quite some time. My current mobo is a Biostar N68S3+ and I am preparing to upgrade with a ASRock 970M which has UEFI. I will be keeping the same CPU, RAM, disks and add-on cards. I have not used UEFI before and I would like to avoid reinstalling my OSs if possible. Slackware is my primary, Win7 is for games and sometimes IT homework.

I have done some searching but still unclear how to prepare my /boot and bootloader before upgrading. Until now I have have always used the LILO bootloader, and just this morning replaced it with GRUB 2.00. I have read references to creating a /boot/efi partition but not clear if it is required and what should be in it. Can GRUB boot my system boot without that partition?
After booting I can deal with drivers. My first concern is booting.

Thanks in advance.

Emerson · 03-06-2016, 01:11 PM

I just went trhu this ordeal a couple of weeks ago. Got it working after resolving some PEBCAK issues.
To my knowledge, yes you must have fat32 formatted boot partition. This is the only format UEFI firmware can access to load the bootloader or EFI stub kernel.

enorbet · 03-06-2016, 01:38 PM

It is my conviction that all of us are mistreated by the word "upgrade" way too often. Way back when I was using Windows 70% of the time, I "upgraded" nearly as a reflex. Over time I began to notice that the changes were really only commonly welcome in hardware drivers and more often than not on other issues caused a lot of work for something I neither needed nor wanted. Specific to UEFI since there really are only a few minor and distinct advantages yet realized, I think you should consider those and if they suit you or if you're better off enabling "Legacy BIOS Mode" which should involve no adjustments.

beachboy2 · 03-06-2016, 02:44 PM

dracolich,

Naturally, backup all your personal data to an external hard drive or similar.

Then relax with a cup of coffee and watch this video:

https://www.youtube.com/watch?v=kBIWSEoWIkw

dracolich · 03-06-2016, 02:53 PM

Thank you, Emerson, I will prepare a fat32 boot partition.

enorbet, I feel the same about upgrading. I remember upgrading a socket7 mobo and CPU almost once per year just because it was so easy. Now I put it off much longer, upgrading when the benefits are worth the effort. In this case I will gain USB3, >8GB max RAM and overclocking to name a few. The manual for the 970M does not mention if a legacy BIOS option is included. I will look into that as well. Thank you.

Emerson · 03-06-2016, 03:47 PM

They call BIOS mode CSM mode in UEFI setup.

dracolich · 03-06-2016, 04:06 PM

Thank you, Emerson!

beachboy2, I always keep most of my important stuff on external disks.
Coffee... check

enorbet · 03-06-2016, 09:24 PM

Just FTR, AFAIK currently the only benefit to UEFI that Legacy Mode can't offer is GPT over MBR which can't properly deal with drives over 2TB. The GUID feature of GPT also has a bit of advantage over the MBR scheme. USB3 and >8GB Ram is not affected and will work equally in either system.

Emerson · 03-06-2016, 09:37 PM

You can use GPT in BIOS mode.

enorbet · 03-07-2016, 05:56 AM

Quote:

Originally Posted by Emerson

You can use GPT in BIOS mode.

Wow! News to me...thanks! One more reason to hang on awhile longer

Emerson · 03-07-2016, 06:40 AM

Some brain dead BIOSes will not boot with GPT, they are looking for boot flag. Fortunately, gdisk will create protective MBR even on GPT disks, so setting the boot flag on protective MBR will keep these BIOSes happy.
Of course, MS Windows will not boot with BIOS+GPT.

dracolich · 03-07-2016, 07:23 AM

Many thanks to you both, enorbet and Emerson, for the thoughts and ideas. I have a lot to learn about the differences between UEFI and BIOS. The book that comes with my new mobo is only a quick start. I found the full manual as pdf last night and it shows where to find CSM mode. My biggest disks are two 1TB drives, one is portable and the other is my NAS. lol So, I have no requirement for UEFI and will definitely go the legacy route. Thanks, guys!

Emerson · 03-07-2016, 01:22 PM

For those interested, below is gdisk output for GPT disk with protective MBR. This disk will boot in legacy BIOS and UEFI machine. Furthermore, gdisk creates protective MBR automatically on its first run, all you need is to save it.

Code:

gdisk /dev/sda -l
GPT fdisk (gdisk) version 1.0.1

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 250069680 sectors, 119.2 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): C7B083E0-B069-4A3A-B1CB-6497D4CA8B39
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 250069646
Partitions will be aligned on 2048-sector boundaries
Total free space is 4061 sectors (2.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048          409600   199.0 MiB   EF00  EFI System
   2          411648       250069646   119.0 GiB   8300  Linux filesystem

dracolich · 03-12-2016, 09:32 AM

Just posting back to say that I have completed the upgrade. With the answers and information I received here the transition was smooth and easy. No problems booting and my Slackware (with kernel 4.2.0) had 0 driver issues. The LQ community rocks!