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

From: Toomas Soome <tsoome_at_me.com>
Date: Fri, 18 Jan 2019 21:42:17 +0200
> On 18 Jan 2019, at 21:33, Rodney W. Grimes <freebsd-rwg_at_pdx.rh.CN85.dnsmgr.net> wrote:
> 
>> 
>> 
>>> On 18 Jan 2019, at 19:57, Lev Serebryakov <lev_at_FreeBSD.org> wrote:
>>> 
>>> On 18.01.2019 20:13, Warner Losh wrote:
>>> 
>>>>> Also, there are same problems with GPT/BIOS setup (which uses GPT but
>>>>> legacy boot) :-(
>>>>> 
>>>> 
>>>> What same problems? I don't think we've touched how gptboot has handed off
>>>> to /boot/loader in a long, long time. It there's an issue here, it's a
>>>> different issue.
>>> Ok, strictly speaking it is different issue with same "high-level"
>>> description: pmbr/gptboot has less features than simplest oldest boot0.
>>> 
>>> pmbr/gptbood doesn't have any way to select partition to boot from, as
>>> "boot0" has. No, setting "nextboot" from live system is not a solution.
>>> I speak about NanoBSD situation when there is tow partitions, both
>>> bootable, one marked as "active" ("bootme" on GPT parlance) but it is
>>> completely broken and user need to boot from other one form very
>>> beginning. This task is trivially solved by "boot0" in pure-MBR case.
>>> What about GPT/Legacy and GPT/UEFI?
>>> 
>>> -- 
>>> // Lev Serebryakov
>>> 
>> 
>> errm.. you press a key and enter device and or loader path. if it is not working - the code is there to be fixed.
>> GPT does not have the concept of active partition.
> 
> It certainly does, it is called the attribute bootme,
> and the above correctly states that.
> 

Shall you give the reference to specification?:) 

I am very well aware about the “vendor” attributes, and I guess You can make a difference about vendor extensions and specification…  

And regarding to GPT attributes, I personally would avoid writing partition table from the boot loader…

rgds,
toomas
Received on Fri Jan 18 2019 - 18:42:22 UTC

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