Regarding DMA in NT

NTDEV
1

Hello All,

I have a bus mastering device capable of accepting upto 2048 IO requests.
In order to use this facility should I create 2048 adapter objects (by
using HalGetAdapter)?

Thanks in advance,
Jeayram

2

Does you device have 2048 DMA engines which can do DMA simultaneously?
If yes, then you should. I hope, however, that they are very slow,
otherwise they will conflict between themselves when accessing memory
and you won’t get much benefit from having a lot of them.

— xxxxx@ctd.hcltech.com wrote:

Hello All,

I have a bus mastering device capable of accepting upto 2048 IO requests.
In order to use this facility should I create 2048 adapter objects (by
using HalGetAdapter)?

Thanks in advance,
Jeayram

You are currently subscribed to ntdev as: xxxxx@yahoo.com
To unsubscribe send a blank email to %%email.unsub%%

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3

You need only 1 adapter object for your device, even in this case.

Max

----- Original Message -----
From:
To: “NT Developers Interest List”
Sent: Wednesday, March 27, 2002 7:07 AM
Subject: [ntdev] Regarding DMA in NT

> Hello All,
>
> I have a bus mastering device capable of accepting upto 2048 IO requests.
> In order to use this facility should I create 2048 adapter objects (by
> using HalGetAdapter)?
>
> Thanks in advance,
> Jeayram
>
> —
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to %%email.unsub%%
>

4

I will be able to queue upto 2048 (or even more. It is programmable) I/O
requests to my device. Each IO request requires a scatter gather list and
I couldn’t find out the maximum number of bytes that the device can DMA.
My understanding is that if I fix the number of I/O requests that I can be
queued to 256, then I need to create 256 adapter objects and get the map
registers ready. Please correct me if my understanding is wrong.

Thanks and regards,
Jeyaram

5

You can use 1 adapter object with appropriate number of map registers.

Max

----- Original Message -----
From:
To: “NT Developers Interest List”
Sent: Thursday, March 28, 2002 8:43 AM
Subject: [ntdev] Re: Regarding DMA in NT

> I will be able to queue upto 2048 (or even more. It is programmable) I/O
> requests to my device. Each IO request requires a scatter gather list and
> I couldn’t find out the maximum number of bytes that the device can DMA.
> My understanding is that if I fix the number of I/O requests that I can be
> queued to 256, then I need to create 256 adapter objects and get the map
> registers ready. Please correct me if my understanding is wrong.
>
> Thanks and regards,
> Jeyaram
>
> —
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to %%email.unsub%%
>

6

See GetScatterGatherList/PutScatterGatherList. You only need one adapter
object.

=====================
Mark Roddy
Windows XP/2000/NT Consulting
Hollis Technology Solutions 603-321-1032
www.hollistech.com
xxxxx@hollistech.com
For Windows Device Driver Training: see www.azius.com

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@ctd.hcltech.com
Sent: Thursday, March 28, 2002 12:44 AM
To: NT Developers Interest List
Subject: [ntdev] Re: Regarding DMA in NT

I will be able to queue upto 2048 (or even more. It is
programmable) I/O requests to my device. Each IO request
requires a scatter gather list and I couldn’t find out the
maximum number of bytes that the device can DMA.
My understanding is that if I fix the number of I/O requests
that I can be queued to 256, then I need to create 256
adapter objects and get the map registers ready. Please
correct me if my understanding is wrong.

Thanks and regards,
Jeyaram

You are currently subscribed to ntdev as:
xxxxx@hollistech.com To unsubscribe send a blank email to
%%email.unsub%%