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

Yes. Declare your device as DMA-capable, then use ScsiPortGetPhysicalAddress to
get the device-side hardware addresses of the IRP's buffer.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

Hi,

Just make it more clearer I am talking about "target mode" data transfer DMA
setup.
I need to setup - per request data transfer - apart from "uncached
extension" common buffer DMA setup for mailboxes and IOCBs.

There are limitations on how much uncached extension I can allocate with
ScsiPortGetUncachedExtension.

So when I receive [FCP[SCSI CDBs]] in my FC HBA interrupt DPC with data
transfer needs (viz. SCSI read or write).
I need to setup DMA-able memory for FCP-DATA exchange that will follow this
command CDB.
This is the time I wish to setup my "per SCSI target mode operation" DMA.
There are ways to setup DMA as stated in my previous message below, but then
ScsiPort Miniport driver framework puts restriction on this.
I am trying to figure out how people are addressing this with these
restrictions.

So I am figuring out in first place how to DMA setup (i.e. get DMA-able
physical memory) with either common buffer allocated or scatter gather list
created? in Scsiport Miniport driver framework - where I do not have access
to DMA adapter or PDO (physical device object) to use with IoGetDmaAdapter
to get DMA adapter.
Please note HalGetAdapter is not an option for me as it is deprecated and
not supported in Windows IA64.

Then only can I use say ScsiPortGetPhysicalAddress or MmGetPhysicalAddress
to get the logical addresses.

Thanks with best regards
Shailesh

"Maxim S. Shatskih" <maxim@storagecraft.com> wrote in message
news:%23mwcZ7%23pFHA.544@TK2MSFTNGP11.phx.gbl...
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


--------------------------------------------------------------------------------------------------------------------------------------

Create the per-device DMA buffer (this is easy - just declare the size you
want in the init structure) and then subdivide it the way you want. Its DMAble
addresses are also accessible with ScsiPortGetPhysicalAddress with Srb == NULL.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

"Shailesh Chaudhari" <ddkuser@newsgroup.nospam> wrote in message
news:OCxf$2$pFHA.3576@TK2MSFTNGP09.phx.gbl...

Hi,

First thing is I need "per operation" buffers to be set fo DMA "not per
device".

The init time per device size you are talking about is a way to go for
"initiator mode" related data buffer management.

The target mode data buffers is altogether different issue.
It needs to be address separately than ScsiPortGetUncachedExtension (with
SrbExtensionSize given in initialize time).

I need to know how does "ScsiPort Miniport framework" supports - lets say
"packet based" DMA data transfer per "target mode" operation.
To explain "packet based" DMA - Say I have locked user buffers based on
"target mode CDB" that came in.
Now want to use these locked-in physical pages for DMAing the data transfer
expected for this "target mode CDB".

Thanks with best regards
Shailesh


In Miniport allocating such buffers

"Maxim S. Shatskih" <maxim@storagecraft.com> wrote in message
news:%2399AJ$AqFHA.3576@TK2MSFTNGP09.phx.gbl...

What is "target mode"? Are you implementing a SCSI target? Then sorry,
ScsiPort and StorPort cannot help you.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

"Shailesh Chaudhari" <ddkuser@newsgroup.nospam> wrote in message
news:%23dilBOGqFHA.3524@tk2msftngp13.phx.gbl...

Hi,

You got it, as I mentioned before

Yes, I am implementing SCSI target in the same code base of my initiator
driver which is a Scsiport Miniport.

My posting is for figuring out how people are addressing this today and are
there any Microsoft recommendations around this.

Thanks with best regards
ddkuser


"Maxim S. Shatskih" <maxim@storagecraft.com> wrote in message
news:%23LV%23kYGqFHA.2960@TK2MSFTNGP10.phx.gbl...