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From: "valerij zaporogeci" <vlrzprgts@gmail.com>
Date: Fri, 28 Jan 2022 02:34:06 +0200
Message-ID: <CANPuzFwSeBsPqOGs2oc313s6fNqumC189LW-gKm=J=hR2n-qrA@mail.gmail.com>
Subject: Question about Block IO protocol devices
To: devel@edk2.groups.io
Content-Type: text/plain; charset="UTF-8"

Hi, edk2. I would be glad to clarify one thing. When I request all
handles, on which Block IO protocol (BIOP) is installed (through
LocateHandleBuffer(ByProtocol), and then open Device Path protocol
(DPP) on every of them to see what devices support BIOP, I don't see
ones, that should represent the whole physical (raw) disk. In other
words, there are no devices, whose DP would end with 4.1 Type.SubType
node _and_ partition number n == 0, this is what the spec suggests as
a way of representing the whole (raw) disk (as opposite to a
partition, on which n =/= 0). Instead, I am getting BIOP instances on
devices, whose DP ends at the level before, a parent device that is,
for example, say 3.1 (Messaging.ATAPI). These are supposedly for
representing the whole (raw) disk? because there are no other thing
being that. E.g. if I have a harddisk with MBR and one partition on
it, the DP for the partition device, supporting BIOP, would be
something like:

PciRoot(0)\Pci(0, 0)\Ata(0)\HD(1, MBR, sign, start, size)

But there wouldn't be a device enumerated like:

PciRoot(0)\Pci(0, 0)\Ata(0)\HD(0,MBR, sign)

Instead, there would be one like this:

PciRoot(0)\Pci(0, 0)\Ata(0)

the question is:
what DP the specification defines to represent a whole (raw) disk?
1) the one, ending with 4.1 Type.SubType and partition number n == 0
2) the DP of the parent of any partition, residing on it, for example
the one, ending with 3.1 Type.SubType

Thank you.