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Re: GPT/UEFI booting

I’m often wrong in my assumptions and that could be the case here.  But it seems to me the “hd0” portion of the disk reference used by boot really refers to the underlying physical disk, not the wedges.  In my case it maps to “ld0” but it just as easily could have mapped to “wd0” or “sd0”.  The “a” portion of the “hd0a” refers to the GPT index on the physical disk.  So the wedge nomenclature doesn’t really apply.  In my case my NetBSD root partition was the part of the disk mapped by the second GPT index, so my boot command needed to be “hd0b” instead of “hd0a” which referenced the EFI portion of the disk mapped by the first GPT index. 

The “hd” nomenclature has always seemed a bit confusing to me and makes me think it came from the Linux world.  But in the case here with GPT disk setup it really seems to be making sense to me now.


On Feb 28, 2017, at 9:19 PM, Thomas Mueller <> wrote:

> On Tue, 28 Feb 2017, Robert Nestor wrote, and Paul Goyette responded:
>>> However, I faithfully implemented your advice and lo-and-behold I
>>> almost have a booting system!  It does come up with the NetBSD boot
>>> menu and then fails because it can't find the NetBSD kernel file on
>>> hd0a.  Of course, that's the EFI/FAT16 partition, so I entered "boot
>>> hd0b:netbsd" at the prompt and I'm up and running!
>> Kewl!
>>> I'm thinking there must be some configuration file I can play with
>>> that modifies this behavior, but for now I’m one happy camper!
>> /boot.cfg is usually where the boot menu is located, probably on the FAT16
>> partition.  Change the boot commands appropriately...
> This "boot hd0b:netbsd" raises the question, how are disk devices and partitions notated for GPT when at the boot prompt and dk0, dk1 might not be understood, and there is no traditional NetBSD disklabel??
> Or is "boot" behind the times in this aspect?
> Tom

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