# Wanting to Install to MBR Drive, But Afraid to Proceed



## LaneLester (Oct 17, 2018)

My computer uses the BIOS (MBR) system for partition management, not UEFI. I read that FreeBSD can be installed on my kind of system. I burned and ran the dvd1 .iso. The beginning text said it was an EFI loader, which made me nervous. But I went ahead.

When I got to the manual partition setup (I have a number of partitions for OSes), I decided I needed more information to proceed. So here I am, hat in hand.

I have a 20 GB slice where I want to put FreeBSD, and it's currently formatted ext4 (Linux). There didn't seem to be any way to just format it as ZFS, so I deleted it. When I tried to create a partition in the space, I had to choose a disk format. When I chose my current MBR scheme, I got the message that it is not bootable.

I sure would appreciate some help, because I sure want to use FreeBSD.

Lane


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## ShelLuser (Oct 17, 2018)

Just because the PC uses a BIOS doesn't automatically mean that you're stuck with MBR. MBR (Master Boot Record) is simply a specific way in which the HD gets partitioned, which starts with the boot sector used to boot the OS.

But there's nothing stopping you from choosing to use GPT instead, which is what I'd suggest (depending on the other OS'es, if one of those is Windows then you're probably better off with MBR).

Anyway, what boot manager do you use? You mentioned using ZFS but to my knowledge not every boot manager will be able to boot from that. And I assume that you didn't rely on FreeBSD's boot manager.. I'm not even sure from mind if this will even work..

See; a common setup is to use GPT where you basically use 2 (or 3) partitions: one which actually boots the system (partition type freebsd-boot) and one which contains the OS (type freebsd-zfs). However, if I recall correctly then MBR relies on the setup where you have one partition in which you define several slices for the different file systems, which means that you also boot from that one partition. But if that is ZFS then I'm not certain that every boot manager will be able to boot from that.


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## LaneLester (Oct 18, 2018)

Thanks for the reply. I use Linux GRUB2 to select the partition to boot. I looked into converting from MBR to UEFI (GPT=UEFI?), but it looked like there was too much opportunity for disaster.

I'm hoping to stick with my GRUB2 and not use the FreeBSD boot manager. I was hoping this in my grub.cfg would to the trick:
menuentry "FreeBSD"{
set root=(hd0,4)
chainloader +1
}

Lane


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## xtaz (Oct 18, 2018)

GPT is not UEFI. I've been using GPT partitioning on all of my boxes for several years now. I use three partitions. freebsd-boot, freebsd-swap, and freebsd-zfs and install bootcode into the freebsd-boot partition using the gpart tool. MBR works identically to this, just the bootcode and partition table is different.

UEFI replaces the freebsd-boot partition with a freebsd-efi one which is basically FAT32, and which just has the boot loader file copied to it rather than using gpart like you do with MBR and GPT.


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## Maccraft123 (Oct 30, 2018)

Just install like usual. Add this to /etc/grub.d/30-freebsd.conf on grub partition:
menuentry "FreeBSD" {
set root='hd0,4'
chainloader /boot/loader
}
I use it personally


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## Emrion (Oct 30, 2018)

GPT scheme is a part of the EFI standard (see https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface). And indeed, a GPT header begins with following bytes: EFI PART.

it's just that there is a possibility to boot a GPT scheme with BIOS. And FreeBSD is one of the rare OS which permits that. So, technically, a GPT scheme can be booted by BIOS (thanks to the protective MBR that begins GPT).

Concerning GRUB, I doubt it can boot on a ZFS partition or, at least, it seems rather complicated. But I do not know this domain.

If I had a similar issue, I will test it on a virtual machine before to proceed.


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## Maccraft123 (Oct 30, 2018)

GRUB can chainload /boot/loader from ZFS


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## ikbendeman (Oct 30, 2018)

If you want to stick with MBR, just create a FreeBSD slice in an MBR partition. The installer makes it easy, and, anyways, that was the default until like 5 years ago.


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