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GPT EFI Partitions

Hello list,

Problem:

When attaching a ZFS pool disk to Windows, it fails to recognise the
partitions used with ZFS. The default layout being MBR protected EFI
partition table.

If opening the \PhysicalDrive1 by hand, the calls to
IOCTL_DISK_GET_PARTITION_INFO or IOCTL_DISK_GET_DRIVE_GEOMETRY_EX will only
see the MBR partition.

Likewise, FindFirstVolume() / FindNextVolume() will not iterate the
partitions that I am interested in. Since, of course, nothing has created
the \Volume{} entries needed.

Currently I use libefi, and read the EFI partition table myself, and a
temporary hack to access the data.

It would be nice however, if I can make it support GPT/EFI partition table,
and have the \Volumes{} created and everything can follow standard Windows
methodology.


Solution?

I have been reading disk.sys in the open sourced Windows-Samples repository.

I am *guessing* that disk.sys is given (fed? probed? scanned?) a list of
\PhysicalDriveX - where it tries to read the partition table, and for each
valid partition, creates the \Volumes{} node(s).

Is that right? In the ball park?

I compiled in the disk.sys sources to ZFS, and run it.. only to find that
nothing really happens. Sure, the "ClassAddDevice = DiskAddDevice" callback
is triggered once, but it doesn't seem to be a \PhysicalDriveX that it is
given (is it a filter?), so clearly I am guessing wrong as to what disk.sys
does.

Ignoring the \PhysicalDriveX situation, I try to simply call disk.sys's
DiskCreateFdo() to create my own \Volumes{}. But it takes a
PhysicalDeviceObject. Does it always have to attach to an existing
\PhysicalDriveX node? Can't I just make one up? It currently fails at
IoAttachDeviceToDeviceStack() with 0xc0000001.

I know this question is a bit vague, and it must be tedious to work with a
hardcore Unix guy like myself, but I would appreciate any wisdom you can
throw my way :)

My hack/slash way to attempt a \Volume{} to appear is here:

https://github.com/openzfsonwindows/ZFSin/blob/WIP.disk.sys/ZFSin/zfs/module/zfs/zfs_vnops_windows_lib.c#L1004

Lund

--
Jorgen Lundman | <xxxxx@lundman.net>
Unix Administrator | +81 (0)90-5578-8500
Shibuya-ku, Tokyo | Japan
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