RE: Communication between smbus driver and miniport drive r.

> Hi All,

How can I send an IRP from SMBus client driver to Miniport
driver? Is there
a way to share memory between two kernel device drivers?

I’m not sure how official/if this is approved by MS, but we’re certainly
using shared memory blocks from the miniport to the display driver, and
accessing them independent of IOCTL calls. Since some of this is done very
frequently, we don’t want to have the extra clock cycles of calling into the
OS, just to read a couple of bytes that happen to be owned by the miniport,
if you see what I mean.

This statement is true for Video miniports, but I expect it’s true for other
miniports too:
Anything allocated by the miniport is always available to the rest of the
system, but display driver allocations may disappear from “view” for the
other parts of the system (particularly in fast user switching or terminal

So, when we need to share some data between the miniport and display driver,
we implement an IOCTL call to ask for the pointer to the data, and then use
the pointer to access the data until further notice. This obviously only
works if the miniport agrees to keep the data around until told otherwise



Questions? First check the Kernel Driver FAQ at

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By default all the memory of krnl-mode is shared, but w/o proper knowledge this raw sharing does not have any symantics. Just use inter-driver communication mechanism to share/interpret shared memory, it is one of the std way.