UEFI booting survey

Maxim Sobolev sobomax at freebsd.org
Mon Dec 18 20:21:22 UTC 2017

Not really specific to UEFI, but when ZFS is in use the /boot might be
partially or fully located on the drive that does not correspond to your
boot drive. We've bumped into this issue on AWS recently when our kernel
ended up on second drive after upgrade in a pool that were spanning two EBS
volumes. Now, it does not work with AWS (as boot code only has access to
the boot EBS volume apparently), but according to Alan such scenario is
totally supported on a physical hardware. So I am worried that by not
allowing loader to scan all drives in the system you'd make this scenario
fundamentally impossible.


On Mon, Dec 18, 2017 at 5:50 AM, Jakob Alvermark <jakob at alvermark.net>

> On 12/17/17 20:52, Warner Losh wrote:
>> Greetings
>> If you are booting off UEFI and have a bit of an unusual setup, I'd like
>> you to drop me a line.
>> The setup that I'm looking for is any case where you load boot1.efi off
>> one
>> drive (cd, ssd, hdd, nvme, etc), but don't have a FreeBSD system on that
>> drive, but on a different drive on the system.
>> An example of this may be loading boot1.efi off what FreeBSD would call
>> /dev/ada0p1, but having root come from /dev/ada1p1.
>> It's my belief that due to the fragility of this setup, few, if any,
>> people
>> have this setup. If you do, please take a minute to reply to this message.
>> In the coming months, we're looking at dropping boot1.efi and instead
>> installing /boot/loader.efi onto the ESP (most likely as
>> \efi\freebsd\loader.efi). As part of the move to fully support the UEFI
>> Boot Manager, we're dropping the 'search every device in the system' part
>> of the current boot1 algorithm. It will be possible to configure the
>> system
>> to continue booting (either via the new efibootmgr which will allow any
>> imaginable combination, or possibly via a fallback mechanism needed for
>> the
>> embedded EFIs that have poor UEFI Variable support at the moment), but as
>> part of an upgrade to a future FreeBSD 12, some intervention will be
>> necessary.
>> Please let me know if you have an unusual setup like this.
>> Warner
> Hi Warner,
> I have what I guess is an unusual setup, not like what you describe above,
> but unusual because I tripple-boot my laptop using only the UEFI boot
> manager to select the OS to boot.
> I have FreeBSD-current, OpenBSD-current and Windows 10 on different
> partitions on one SSD. By default it boots FreeBSD.
> This was accomplished with bcdedit.exe in Windows, but now I realize this
> could be done with the new efibootmgr.
> I wanted to try it out, but it panics on my laptop. Sometimes just
> 'kldload efirt' just panics, sometimes it loads but panics as soon as I run
> efibootmgr or efivar.
> How can I help debugging this?
> Jakob
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