FreeBSD 10.1 i386 encrypted mirrored ZFS root on USB flash drives

[Warren Block]

On Mon, 12 Jan 2015, Adam Vande More wrote:

> On Mon, Jan 12, 2015 at 2:26 PM, David Christensen <
> dpchrist at holgerdanske.com> wrote:
>
>> freebsd-questions:
>>
>> I did another install, set the protective MBR boot flag on the USB drives
>> using Linux fdisk, booted the machine, entered the encryption passphrase,
>> and it crashes:
>>
>>         Enter passphrase for da0p4: GEOM_MIRROR: Force device swap start
>> due to timeout.
>>
>>         GEOM_ELI: Device da0p4.eli created
>>         GEOM_ELI: Encryption: AES-XTS 256
>>         GEOM_ELI:     Crypto: software
>>         GEOM_MIRROR: Cancelling unmapped because of da0p3.
>>         GEOM_MIRROR: Device mirror/swap launched (1/2).
>>         GEOM_ELI: Device da1p4.eli created.
>>         GEOM_ELI: Encryption: AES-XTS 256
>>         GEOM_ELI:     Crypto: software
>>         Trying to mount root from zfs:cd2533/ROOT/default []...
>>
>>         Fatal double fault:
>>         eip = 0xc186ad2e
>>         esp = 0xea4f2000
>>         ebp = 0xea4f2360
>>         cpuid = 0; apic id = 00
>>         panic: double fault
>>         cpuid = 0
>>         KDB: stack backtrace:
>>         #0 0xc0b53ed2 at kdb_backtrace+0x52
>>         #1 0xc0b1688f at panic+0x11f
>>         #2 0xc101bedb at dblfault_handler+0xab
>>
>>
>> Any ideas?
>>
>
> A guess would be that it's USB related.  I think your boot flag stuff is a
> red herring.  Maybe STABLE or USB mailing lists could shed more detail.

As I (possibly incorrectly) understand it, using the boot flag in a PMBR 
depends on the BIOS.  BIOS sees the PMBR as an MBR, and a strict BIOS 
might not boot a drive without any MBR partitions set to boot.  I've 
been told that most should boot without it.

The GPT spec says that the boot flag in the PMBR should not be set, so a 
strict UEFI will *not* boot with it.  I know this has been seen, but I 
can't recall on which types of systems.  Maybe Lenovo, or possibly Asus.