Converting the FreeBSD 15.0 installation from BIOS to UEFI on VMware
When it comes to changing the boot method from BIOS to UEFI in operating systems, this won’t work by just a single toggle, unless you create a UEFI partition that contains the EFI/BOOT/BOOTX64.EFI file on 64-bit computers. UEFI on such computers looks for a valid EFI System Partition (ESP) on your hard disk whose partition table is GPT, mounts it as FAT32, then looks for a boot file mentioned earlier. Then, the boot file gets loaded, which causes the bootloader to load the kernel to RAM, which will then give control to the kernel as the OS loads.
When you install FreeBSD to your computer, it lets you partition the disk either manually or automatically. if you have installed it in BIOS mode, and you want to change the boot method so that it uses UEFI, you can’t just change the boot mode in your BIOS setup to UEFI and expect things to work; you’ll need much more than that. We will highlight how we’ve managed to convert a FreeBSD 15.0 installation from BIOS to UEFI in a VMware virtual machine.
We will assume that your partition table is already set to GPT, and that you’ve used ZFS to install FreeBSD, just like below:
Before you proceed, please make sure that you know what you’re doing. Carefully read the disk identifiers and the disk partition tables, including the geom disk list and the gpart show outputs, as one mistake or typo is catastrophic. This article also assumes that you have a partition table you can modify to make space for the EFI partition, such as in our case, since UFS and ZFS are not easily shrinkable. If your partition table doesn’t allow you to make some space for the ESP partition, you’ll have to use other methods, and they may not be safe.
First of all, boot into your FreeBSD system on BIOS boot mode after installation. Then, if you are logging in as root, remove sudo before every command listed in this article. Else, log in to your account with sudo permissions.
Now, execute both geom disk list and gpart show <your disk id>. Your disk IDs and partition indexes may be different, so adjust accordingly to prevent yourself from editing the wrong disk!
aptivi@apt-freebsd-01:~ $ sudo geom disk list Password: Geom name: cd0 Providers: 1. Name: cd0 Mediasize: 1359900672 (1.3G) Sectorsize: 2048 Mode: r0w0e0 descr: NECVMWar VMware IDE CDR10 ident: (null) rotationrate: unknown fwsectors: 0 fwheads: 0 Geom name: da0 Providers: 1. Name: da0 Mediasize: 214748364800 (200G) Sectorsize: 512 Mode: r2w2e3 descr: VMware, VMware Virtual S ident: (null) rotationrate: 15000 fwsectors: 63 fwheads: 255 aptivi@apt-freebsd-01:~ $ sudo gpart show da0 => 40 419430320 da0 GPT (200G) 40 1024 1 freebsd-boot (512K) 1064 984 - free - (492K) 2048 4194304 2 freebsd-swap (2.0G) 4196352 415232000 3 freebsd-zfs (198G) 419428352 2008 - free - (1.0M) As you can see, our FreeBSD installation is found at da0 > freebsd-zfs, index 3 (da0s3). A sour truth is that you can’t easily shrink this partition, but we are easily able to shrink the swap partition to make room for the UEFI partition. So, we have decided to shrink the swap partition, which is index 2 (da0s2). You’ll have to turn off swapping before the shrinking operation with swapoff /dev/da0s2.
aptivi@apt-freebsd-01:~ $ sudo swapoff /dev/da0p2 aptivi@apt-freebsd-01:~ $ sudo gpart resize -i 2 -s 1024M da0 da0p2 resized aptivi@apt-freebsd-01:~ $ sudo swapon /dev/da0p2 aptivi@apt-freebsd-01:~ $ sudo gpart show da0 => 40 419430320 da0 GPT (200G) 40 1024 1 freebsd-boot (512K) 1064 984 - free - (492K) 2048 2097152 2 freebsd-swap (1.0G) 2099200 2097152 - free - (1.0G) 4196352 415232000 3 freebsd-zfs (198G) 419428352 2008 - free - (1.0M) Now, we have a 1024 MB free disk space just before the ZFS partition. We will now add the UEFI partition with FAT32 as the type, which will use index 4 (da0s4), with sudo gpart add -t efi -s 1024M -a 4K da0:
aptivi@apt-freebsd-01:~ $ sudo gpart add -t efi -s 1024M -a 4K da0 da0p4 added aptivi@apt-freebsd-01:~ $ sudo gpart show da0 => 40 419430320 da0 GPT (200G) 40 1024 1 freebsd-boot (512K) 1064 984 - free - (492K) 2048 2097152 2 freebsd-swap (1.0G) 2099200 2097152 4 efi (1.0G) 4196352 415232000 3 freebsd-zfs (198G) 419428352 2008 - free - (1.0M) The ESP partition has been created with index 4. Now, we will create a FAT32 filesystem on da0s4, then copy the UEFI bootloader files to the EFI system partition. Execute the below commands, but make sure that you execute them with the correct disk identifier. Also, check to see if loader.efi or similar exists in /boot with ls /boot/*.efi.
aptivi@apt-freebsd-01:~ $ sudo newfs_msdos /dev/da0p4 /dev/da0p4: 2096064 sectors in 65502 FAT16 clusters (16384 bytes/cluster) BytesPerSec=512 SecPerClust=32 ResSectors=32 FATs=2 RootDirEnts=512 Media=0xf0 FATsecs=256 SecPerTrack=63 Heads=255 HiddenSecs=0 HugeSectors=2097152 aptivi@apt-freebsd-01:~ $ sudo mount -t msdosfs /dev/da0p4 /mnt aptivi@apt-freebsd-01:~ $ sudo mkdir -p /mnt/EFI/BOOT aptivi@apt-freebsd-01:~ $ ls /boot/*.efi /boot/boot1.efi /boot/loader.help.efi /boot/loader_lua.efi /boot/gptboot.efi /boot/loader_4th.efi /boot/loader_simp.efi /boot/loader.efi /boot/loader_ia32.efi aptivi@apt-freebsd-01:~ $ sudo cp /boot/loader.efi /mnt/EFI/BOOT/BOOTX64.EFI aptivi@apt-freebsd-01:~ $ sudo umount /mnt After copying the bootloader file, we need to add the ESP partition to the filesystem table file, /etc/fstab, which FreeBSD uses to automatically mount all the listed filesystems. This is so that bootloader upgrades go smoothly without any failures.
Again, use the correct disk identifier that corresponds to your ESP partition. Use sudo vi /etc/fstab to edit the file interactively to have a chance to review the mistakes before you save the file. For example, we’ve added the below line:
/dev/da0p4 /boot/efi msdosfs rw 0 0 After that, the file should look like this:
aptivi@apt-freebsd-01:~ $ cat /etc/fstab # Device Mountpoint FStype Options Dump Pass# /dev/da0p2 none swap sw 0 0 /dev/da0p4 /boot/efi msdosfs rw 0 0 Now, it’s time to shut down your FreeBSD installation. Once the shutdown process has finished, open the virtual machine settings, go to Options > Advanced, and select UEFI in the boot method. Don’t enable Secure Boot, as FreeBSD doesn’t support Secure Boot at all.
If everything goes well, and you’ve executed the commands correctly, you should now be able to see the improved bootloader screen with an actual image of FreeBSD, just like below:
Let FreeBSD boot up to the login prompt, then verify that machdep.bootmethod says UEFI:
aptivi@apt-freebsd-01:~ $ sysctl machdep.bootmethod machdep.bootmethod: UEFI
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