Re: GPT boot has less features than legacy MBR-based one (Was: UEFI, loader.efi and /boot.config)

From: Lev Serebryakov <lev_at_FreeBSD.org>
Date: Fri, 18 Jan 2019 22:50:31 +0300
On 18.01.2019 22:35, Rodney W. Grimes wrote:

>>> errm.. you press a key and enter device and or loader path. if it is not working - the code is there to be fixed.
>>  And loader looks to "bootme" attribute and try to boot from partition
>> which has one, even if it is loaded from other partition itself.
>>
>>> GPT does not have the concept of active partition.
>>  It has "bootme" / "bootonce" attributes. And [zfs]gptboot doesn't have
>> any tools to set these attributes, AFAIK. Same for UEFI boot code.
> 
> The gpart(8) command is used to set/unset these.
 gpart need booted system. NanoBSD typically have two "system"
partitions, "old" (previous) and "new" (current). After upgrade they
switched (new code is written to "previos" partition and bootable
atteibute is set to it, "active" in case of MBR and "bootme" in case of
GPT).

  If this new partition has problems and could not be booted, it is hard
to boot from "old" (previous) one. MBR + boot0 could (interactively)
change active partition before system is booted, and this problem could
be solved with one keypress: you select old partition on boot.

-- 
// Lev Serebryakov


Received on Fri Jan 18 2019 - 18:50:33 UTC

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