Date: Fri, 18 Jan 2019 12:40:53 -0800 (PST) From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net> To: Toomas Soome <tsoome@me.com> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: GPT boot has less features than legacy MBR-based one (Was: UEFI, loader.efi and /boot.config) Message-ID: <201901182040.x0IKermY057311@pdx.rh.CN85.dnsmgr.net> In-Reply-To: <96BDA1B2-32FA-4FA1-AAD1-612BC3324373@me.com>
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> > On 18 Jan 2019, at 21:33, Rodney W. Grimes <freebsd-rwg@pdx.rh.CN85.dnsmgr.net> wrote:
> >
> >>
> >>
> >>> On 18 Jan 2019, at 19:57, Lev Serebryakov <lev@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?:)
You can bury yourself in that paradigm, but the fact is even the wiki documents
gpt attribute bit 2 as "legacy bootable, equivelant to active flag".
>
> 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?
I never advocated writing to anything from the loader.
--
Rod Grimes rgrimes@freebsd.org
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