Hello from Userland.
The docs for WinUsb_RegisterIsochBuffer() notes that ‘allows the Winusb.sys
to pre-map and lock the buffer after for all subsequent transfers using the
buffer.’
Does this mean that subsequent host <=> device transfers are not
significantly impacted in terms of latency?
More generally what are the signing/WHQL requirements for UMDF drivers?
From the (ancient) blog here I assume code signing is a must:
http://blogs.msdn.com/b/peterwie/archive/2007/01/23/do-umdf-drivers-require-
signing.aspx
An slightly newer thread here:
https://www.osronline.com/showThread.CFM?link=199863 is somewhat unclear re
WHQL? Is this required at all?
Many thanks.
Jerry.
Whql policy and requirements are applied the same to both user and km drivers
d
Bent from my phone
From: xxxxx@chordia.co.ukmailto:xxxxx
Sent: ?4/?19/?2015 4:51 AM
To: Windows System Software Devs Interest Listmailto:xxxxx
Subject: [ntdev] 2 UMDF questions …
Hello from Userland.
The docs for WinUsb_RegisterIsochBuffer() notes that ‘allows the Winusb.sys
to pre-map and lock the buffer after for all subsequent transfers using the
buffer.’
Does this mean that subsequent host <=> device transfers are not
significantly impacted in terms of latency?
More generally what are the signing/WHQL requirements for UMDF drivers?
From the (ancient) blog here I assume code signing is a must:
http://blogs.msdn.com/b/peterwie/archive/2007/01/23/do-umdf-drivers-require-
signing.aspx
An slightly newer thread here:
https://www.osronline.com/showThread.CFM?link=199863 is somewhat unclear re
WHQL? Is this required at all?
Many thanks.
Jerry.
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Thx.
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Doron Holan
Sent: 19 April 2015 14:43
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] 2 UMDF questions …
Whql policy and requirements are applied the same to both user and km
drivers
d
Bent from my phone
xxxxx@chordia.co.uk wrote:
The docs for WinUsb_RegisterIsochBuffer() notes that ‘allows the Winusb.sys
to pre-map and lock the buffer after for all subsequent transfers using the
buffer.’
Does this mean that subsequent host <=> device transfers are not
significantly impacted in terms of latency?
I’m not sure what you’re asking here. UMDF drivers do pay a small
penalty over KMDF drivers just because of the user/kernel transitions.
In a host->device transaction, that penalty is irrelevant, because it is
swallowed up in the latency on the wire. In the device->host direction,
it takes a little longer for you to be able to process the data you
got. Whether that delay is meaningful depends on your application.
–
Tim Roberts, xxxxx@probo.com
Providenza & Boekelheide, Inc.