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From: yushang on 26 Sep 2009 08:45
Dear all , is it possible to receive a SRB with NULL DataBuffer ? The
SCSI command is SCSIOP_READ (0x28) and the DataTransferLength is not
zero . Thanks in advance
From: Alexander Grigoriev on 26 Sep 2009 11:01
This means the buffer doesn't have any user mode or kernel mode mapping.
Usually that's paging IO or lazy write.

You can only use DataBuffer of a read/write command to pass to
StorBuildScatterGatherList.

"yushang" <yusunn(a)gmail.com> wrote in message
news:54ee6542-7535-4cc1-abe8-08542d7dc427(a)i4g2000prm.googlegroups.com...
> Dear all , is it possible to receive a SRB with NULL DataBuffer ? The
> SCSI command is SCSIOP_READ (0x28) and the DataTransferLength is not
> zero . Thanks in advance


From: yushang on 26 Sep 2009 11:26
On Sep 26, 11:01 pm, "Alexander Grigoriev" <al...(a)earthlink.net>
wrote:
> This means the buffer doesn't have any user mode or kernel mode mapping.
> Usually that's paging IO or lazy write.
>
> You can only use DataBuffer of a read/write command to pass to
> StorBuildScatterGatherList.
>
> "yushang" <yus...(a)gmail.com> wrote in message
>
> news:54ee6542-7535-4cc1-abe8-08542d7dc427(a)i4g2000prm.googlegroups.com...
>
> > Dear all , is it possible to receive a SRB with NULL DataBuffer ? The
> > SCSI command is SCSIOP_READ (0x28) and the DataTransferLength is not
> > zero . Thanks in advance

Is DataBuffer related to MapBuffers of
PORT_CONFIGURATION_INFORMATION ? If so , it seems this is a
functionality provided by Scsiport layer . And I got the SRB directly
from the disk class dirver. It seems there is nothing to do with
Scsiport .
From: Maxim S. Shatskih on 26 Sep 2009 15:48
> functionality provided by Scsiport layer . And I got the SRB directly
> from the disk class dirver.

At this level, Srb->DataBuffer is probably undefined, and the buffer is at Irp->MdlAddress

--
Maxim S. Shatskih
Windows DDK MVP
maxim(a)storagecraft.com
http://www.storagecraft.com

From: Alexander Grigoriev on 26 Sep 2009 15:48
Originally, DataBuffer contains the same as
MmGetMdlVirtualAddress(Irp->Mdl)+offset (offset is non-zero if SRB is a
result of breaking a big request to smaller chenks). Storport/Scsiport can
replace it with mapped buffer address, if MapBuffers requires that.

"yushang" <yusunn(a)gmail.com> wrote in message
news:e3de83e6-8388-429b-8526-02ac7d254e85(a)v15g2000prn.googlegroups.com...
> On Sep 26, 11:01 pm, "Alexander Grigoriev" <al...(a)earthlink.net>
> wrote:
>> This means the buffer doesn't have any user mode or kernel mode mapping.
>> Usually that's paging IO or lazy write.
>>
>> You can only use DataBuffer of a read/write command to pass to
>> StorBuildScatterGatherList.
>>
>> "yushang" <yus...(a)gmail.com> wrote in message
>>
>> news:54ee6542-7535-4cc1-abe8-08542d7dc427(a)i4g2000prm.googlegroups.com...
>>
>> > Dear all , is it possible to receive a SRB with NULL DataBuffer ? The
>> > SCSI command is SCSIOP_READ (0x28) and the DataTransferLength is not
>> > zero . Thanks in advance
>
> Is DataBuffer related to MapBuffers of
> PORT_CONFIGURATION_INFORMATION ? If so , it seems this is a
> functionality provided by Scsiport layer . And I got the SRB directly
> from the disk class dirver. It seems there is nothing to do with
> Scsiport .


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