Re: GPT boot, again

[tlaronde%polynum.com@localhost]

On Thu, Jul 25, 2019 at 04:20:59PM +0200, Emmanuel Dreyfus wrote:
> Hello
> 
> I try to boot NetBSD/Xen from a GPT, with little success.
> 
> I understand NetBSD EFI bootstrap does not support multiboot, so I
> should use BIOS boot.
> 
> I installed /boot, ran installboot and gpt biosboot. Here is fdisk
> output for the disk:
> 
> Partition table:
> 0: GPT Protective MBR (sysid 238)
>     start 1, size 4294967295 (2097152 MB, Cyls 0-267349/89/4), Active
>         PBR is not bootable: Bad magic number (0x0000)
> 1: <UNUSED>
> 2: <UNUSED>
> 3: <UNUSED>
> First active partition: 0
> 
> And if I hexdump the disk block 0, I see the strings of a bootstrap
> present.
> 
> But the BIOS will not consider the disk for booting. I made it the first
> priority, but it just skips to the next one.
> 
> I wonder if "PBR is not bootable: Bad magic number" may be at fault
> here. Any idea?

I guess it's on a i386/amd64 arch? Because, if my memory is right, 
there is the need of the "\x55\xAA" in the two last bytes of the
first 512b block (the signature) for the BIOS.
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                       http://www.sbfa.fr/
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