On Mon, Jun 29, 2020 at 11:44:40AM -0400, Hendrik Boom wrote:
> On Tue, Jun 30, 2020 at 12:36:58AM +1000, terryc wrote:
> > On Mon, 29 Jun 2020 08:18:24 -0400
> > Hendrik Boom <hendrik@???> wrote:
> >
> >
> > > Does it determine which MBRs to update by looking at the BIOS 'boot'
> > > flags?
> >
> > As I understand it, the boxen looks at the UEFI(?) for the pointer to
> > which piece of HW carries the initial loader, which then loads "grub"
> > and its configuration files and the modules it needs to access the
> > basic system to build up the OS to the final system.
>
> My hardware does not do UEFI. It is a BIOS system.
>
> Two of the drives are smallish, and have the old-style partitioning,
> with four primary partitions, one of which is subdivided into secondary
> partitions, One of these drives is the problem.
>
> I have two large EFI-partitioned disks, starting of course with

Correction. They are GPT-patitioned disks. EFI is a boot procedure
which I don't use; GPT is a prartinioning scheme. I confused the two
acronyms.

> "protective MBR"s. These are working properly.
> /boot is on these drives. Well, actually in one partition on each of
> them, these partitions paired off as a software RAID.
>
> >
> > The only file that I can find that points to any articular piece of
> > hardware is /boot/grub/grub.cfg, which shoud list the various boot
> > menu options. which points to hd0 with a device-id.
>
> Looked through that. It contains descriptions of all the operating
> systems on my disk drives, identified by some kind of UUID. It does not
> seem to have anything describing where boot from initially to load grub
> stage 1 or grub stage 1.5. This is what I expected, because the
> early stages of Grup already have to be loaded and running before it
> can even understand the /boot file system.
> Grub stage 1.5 presumably looks through the menu and figures out what
> partition contains the /boot it si supposed to look for.
>
> >
> > > Or is there some configuration file somewhere?
> >
> > So when (for me) sudo apt-get dist-upgrade loads newer images and runs
> > grub-update/update-grub/?? is runs it probably checks what is in the
> > existing grub.cfg and just adjust the various boot menu options(add
> > newest, drops oldest).
> >
> > If you can get the machine to boot, there is a method to
> > copy the grub config to a floppy or I guess a usb stick
> > these days.
>
> Machine boots fine. Just won't upgrade.
>
> >
> > At one stage, writing a spare boot floppy and keeping it up todate was
> > recommended.
>
> I used to do that, but no loger have a floppy drive. I'd have to use a
> USB stick, or perhaps even a Devuan installer used as a rescue disk.
>
> -- hendrik
>
> >
> > Remember the reference to the hardware wll be 'primative' as t only has
> > a basic system at first.
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