Question on fdo->Flags buffering method

NTDEV
1

Hi,

I understand that either DO_BUFFERED_IO or DO_DIRECT_IO to be used for fdo Flags parameter.

fdo->Flags |= DO_BUFFERED_IO;
or
fdo->Flags |= DO_DIRECT_IO;

But will this have any effect if I need to use the IOCTL method buffered as well as IOCTL method direct in my driver simultaneously. I would assume I don’t have to bother about any upper or lower filter drivers…

Thanks,

2

The flags on the device object affect read and write IRPs and no other irps. Each IOCTL has its own buffering type (method in, method out, buffered, neither), as specified in a bit field in the ioctl value itself.

d

-----Original Message-----
From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of xxxxx@techie.com
Sent: Sunday, December 16, 2007 8:33 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] Question on fdo->Flags buffering method

Hi,

I understand that either DO_BUFFERED_IO or DO_DIRECT_IO to be used for fdo Flags parameter.

fdo->Flags |= DO_BUFFERED_IO;
or
fdo->Flags |= DO_DIRECT_IO;

But will this have any effect if I need to use the IOCTL method buffered as well as IOCTL method direct in my driver simultaneously. I would assume I don’t have to bother about any upper or lower filter drivers…

Thanks,

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3

No, these flags only affect reads and writes, not IOCTLs.

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

wrote in message news:xxxxx@ntdev…
> Hi,
>
> I understand that either DO_BUFFERED_IO or DO_DIRECT_IO to be used for fdo
Flags parameter.
>
> fdo->Flags |= DO_BUFFERED_IO;
> or
> fdo->Flags |= DO_DIRECT_IO;
>
> But will this have any effect if I need to use the IOCTL method buffered as
well as IOCTL method direct in my driver simultaneously. I would assume I don’t
have to bother about any upper or lower filter drivers…
>
> Thanks,
>
>
>
>
>