Uncached Extension in Storport Miniport Driver

NTDEV
1

Hi All,
I have a very basic question about the RequestedDumpBufferSize member of port configuration information. It is basically the UnCached extension that is allocated during crash dump or hibernation.

My question is why do we need this? Can’t we just use the device extension for the same purposes?

Where can I read more about this.

Thanks
Ajitabh

2

Uncached extension (which doesn’t have to actually be uncached) is just a SCSIPORT word for a comon buffer. You get its physical address and can use it for in-host structures shared with the hardware.

3

One issue is that you would need to figure out how to pass the uncached
extension from the “normal” copy of your driver to the crash dump copy (note
that these drivers do not share any global state).

Previously this wasn’t really feasible. On newer versions (Win7+ or so) this
should be possible through the use of SRB_FUNCTION_DUMP_POINTERS, though I
have not tried this myself.

There isn’t any place to read more about this, StorPort documentation is
quite thin.

-scott
OSR
@OSRDrivers

“Ajitabh Saxena (ajisaxen)” wrote in message
news:xxxxx@ntdev…

Hi All,

I have a very basic question about the RequestedDumpBufferSize member
of port configuration information. It is basically the UnCached extension
that is allocated during crash dump or hibernation.

My question is why do we need this? Can’t we just use the device extension
for the same purposes?

Where can I read more about this.

Thanks

Ajitabh