Re: memory allocation for storport miniport driver.

> i am writing a storport miniport driver and i have to allocate memory.
> which is the best option for allocating memory?

What memory? to what is it associated? to device? to LUN? to a request in progress?

Enlarge the device/LUN/SRB extension on this size.

> my requirement is i have to use that memory which can be accessed by
> both host and device, want to use DMA also.

Device and SRB extensions are DMAable using the same ScsiPortGetPhysicalAddress (at least in ScsiPort).

--
Maxim S. Shatskih
Windows DDK MVP

http://www.storagecraft.com

>is it possible to allocate memory which i dont know during the
>initialization but dynamically e.g. in build io and start io i found
>that i am running out of memory for my command/data transfer

I would probably set the SRB extension size to cover the _largest possible_ command/data transfer.

>need to allocate some more memory? will this function
>"ScsiPortGetPhysicalAddress" works during that time also?

IIRC no. Only the IRP's MDL, the device extension and the SRB extension are covered by this mechanism in SCSIPORT. For instance, LUN extension is not.

--
Maxim S. Shatskih
Windows DDK MVP

http://www.storagecraft.com