How to setup "per target-mode-SCSI-operation DMA" for "target mode" data transfer with **ScsiPort Miniport** driver model


Hi All,

I know that there is no "target mode" support in ScsiPort Miniport driver
framework of Windows.

Here is my question - though in context of "SCSI target mode operations" it
is more related to "being able to setup DMA" -

How to setup "per target-mode-SCSI-operation DMA" for "target mode" data
transfer with **ScsiPort Miniport** driver model?
At-least there should be a "clean documented" way to address such
requirements, until the right support comes in the next versions of this
driver framework.

ScsiPort Miniport framework does not allow setting up DMA separately.

The required objects like "device object" (PDO) to start with to issue
IoGetDmaAdapter are unavailable.
Writing filter drivers to get hold of such hidden information is kind of
overkill.
ScsiPortGetUncachedExtension is the only DMA (common buffer only - with
restrictions on the allocation size) related support which can be done once
for each HwFindAdapter call in the Miniport driver.
This one is only useful for things like HBA mailboxes and IOCBs etc.

One would need to setup DMA for - per SCSI "target mode" operation data
transfers.
Scsiport Miniport driver framework has no support for this.
This will be specifically required when one is attempting this for "target
mode SCSI" operations for say an FC HBA.
Also driver developers are discouraged from using
- MmXXX functions to setup DMA memory for compatibility reasons
- and HalXXX DMA functions as these are being obsoleted with some (like
HalGetAdapter) not being available in Windows IA64.

This is/will be a pretty common case for any ISV trying to write a SCSI
"target mode" driver for FC HBAs say.
And I will be surprised if Microsoft does not support such needs - as this
will just cause people to code in non-standard way causing more support
pressure in absence of right recommendations.

Please provide some guidance or redirect me to appropriate person.

Thanks in advance.

Thanks with best regards
ddkuser


.

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