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From: "valerij zaporogeci" <vlrzprgts@gmail.com>
Date: Fri, 28 Jan 2022 04:19:14 +0200
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Subject: Re: [edk2-devel] Question about Block IO protocol devices
To: Andrew Fish <afish@apple.com>
Cc: devel@edk2.groups.io
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Thank you, Andrew, for the clarification.

> I don=E2=80=99t remember the use case for HD(0,MBR, sign) type of device =
path node?

don't know, how much of usability it would have per se, but
representing a raw disk this way, would give an easier way to find
them out. because all such would end with the same 4.1 Type.SubType
and partition number. without this, a raw disk could be 3.1, or 3.25
or 3.26 or 3.29 or even 1.4 (VenHw(GUID)) or 1.1 (Pci(2, 0)) as is
with OVMF for qemu arm64.

And yet one thing. The Signature field in the 4.1 typed node for the
case of GPT for a partition device. Did I understand correctly, that
its should contain the same GUID as is in the corresponding GUID
Partition Array entry field UniquePartitionGuid for that partition?
Because one implementation (not edk2) puts as the Signature field
DiskGuid in every partition Device Path node.