MDL fields

NTDEV
1

Can someone explain the MDL fields to me. Does the MDL below look allright?
(ByteCount is 94, but the VA space doesnt have that many bytes and there is
nothing more chained to this buffer)… Please clarify my doubt

Thanks
-Johnny

+0x000 Next : (null)
+0x004 Size : 32
+0x006 MdlFlags : 12
+0x008 Process : (null)
+0x00c MappedSystemVa : 0xff94afa8
+0x010 StartVa : 0xff94a000
+0x014 ByteCount : 0x5e
+0x018 ByteOffset : 0xfa8
0: kd> dd 0xff94afa8
ff94afa8 8ce40300 d0003888 6b5d8fb7 00450008
ff94afb8 1b362800 06800040 83d11fc2 83d1d22d
ff94afc8 5b00bc31 790801dd 0fd4cd54 105043a5
ff94afd8 c48ea805 04020000 0301b405 01010003
ff94afe8 00000a08 00000000 ff940000 00000000
ff94aff8 00000000 00000000 ??? ???
ff94b008 ??? ??? ??? ???
ff94b018 ??? ??? ??? ???

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2

The MDL looks alright. The API IoAllocateMdl trusts the MDL passed to it. If
you pass it a bad length then the MDL will contain the wrong length.

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“Johnny D” wrote in message news:xxxxx@ntdev…
>
> Can someone explain the MDL fields to me. Does the MDL below look
allright?
> (ByteCount is 94, but the VA space doesnt have that many bytes and there
is
> nothing more chained to this buffer)… Please clarify my doubt
>
> Thanks
> -Johnny
>
> +0x000 Next : (null)
> +0x004 Size : 32
> +0x006 MdlFlags : 12
> +0x008 Process : (null)
> +0x00c MappedSystemVa : 0xff94afa8
> +0x010 StartVa : 0xff94a000
> +0x014 ByteCount : 0x5e
> +0x018 ByteOffset : 0xfa8
> 0: kd> dd 0xff94afa8
> ff94afa8 8ce40300 d0003888 6b5d8fb7 00450008
> ff94afb8 1b362800 06800040 83d11fc2 83d1d22d
> ff94afc8 5b00bc31 790801dd 0fd4cd54 105043a5
> ff94afd8 c48ea805 04020000 0301b405 01010003
> ff94afe8 00000a08 00000000 ff940000 00000000
> ff94aff8 00000000 00000000 ??? ???
> ff94b008 ??? ??? ??? ???
> ff94b018 ??? ??? ??? ???
>
> _________________________________________________________________
> MSN Photos is the easiest way to share and print your photos:
> http://photos.msn.com/support/worldwide.aspx
>
>
>