USB2 Ajays debug cable case

hi, all

currently, I can use NET to debugging driver on Win8 or later

the target without serial port

So I bought a USB2 debug cable for Win7 debugging.

I setup the target according to the windbg help doc.

But it does not work.

I found, the motherboard with two EHCI host, and each host’s port1 under root hub is a generic usb hub, such as:

PCI to USB host controller
Root Hub
Port1: Generic usb hub
Port 1 <<–plug physical port of the debug cable
Port 2
Port2

So I think it is because I plug the debug cable on port 1 of port 1, then it will not work.

So this motherboard will not work for USB2 debug.

how to determinte a motherboard support EHCI host usb debug capability?

My experience and the experience of many talented Windows kernel
developers I know, is we have NEVER really gotten USB 2 debugging to work
reliably on most systems. I do know someone who did driver work on ARM
WindowsRT and said USB debugging via the USBToGo port did work reliably.
That same developer made a really herculean attempt to get USB 2 debugging
to work on some servers, with no success.

I’ve long ago come to the conclusion that trying to get USB 2 debugging
working on x86 systems is a waste of effort in most cases. There might be
some system out there where it does work reliability, so I don’t want to
say it never works on any system. If you work for the system vendor, and
can walk over to the office of the folks who control BIOS development, you
might be successful. USB 3 kernel debugging on Win 8 and later is a
different case, and if you get/make the correct cable, likely does work,
but is not supported on Win 7.

One trick I read about a couple years ago that was claimed to help was to
set the USB legacy support off in the BIOS, which in some cases means you
could no longer use a USB keyboard to change BIOS settings to reenable USB
legacy support (although you might be able to pull a jumper to force BIOS
defaults).

You should search the history over in the OSR windbg list, as folks from
the Microsoft debugger team sometimes read that list, and this is not a
new question.

You CAN get mini-PCIe 1394 cards, which on some laptops and modern
motherboards which allows debugging via a speedy 1394 link.

It’s a bad assumption that just any machine will be an optimal kernel
debugging target. I know some people swear by legacy serial ports as a
debug transport. Personally, I try really hard to use a LSI Logic chip
based 1394 card as the kernel debug target transport.

Jan

On 12/22/14, 8:28 AM, “workingmailing@163.com
wrote:

>how to determinte a motherboard support EHCI host usb debug capability?
>
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Your experience is identical to that of most Windows devs.

Do not even attempt to use USB 2 debugging unless there is absolutely, positively, completely, and totally no alternative. I’ve seen it work (SNoone here at OSR managed to get it working for a system that has NOTHING but a USB port) but it wasn’t a solid debug connection.

Peter
OSR
@OSRDrivers

On 12/22/2014 1:02 AM, workingmailing@163.com wrote:

PCI to USB host controller
Root Hub
Port1: Generic usb hub
Port 1 <<–plug physical port of the debug cable
Port 2
Port2

So I think it is because I plug the debug cable on port 1 of port 1, then it will not work.

At least on my system (ASUS Z97) the BIOS appears to reconfigure the
layout/configuration of the USB ports depending on what’s connected. I
tried to follow
http://blogs.msdn.com/b/usbcoreblog/archive/2010/10/25/setting-up-kernel-debugging-with-usb-2-0.aspx#_Optional:_Determine_the
but couldn’t find the debug port - I seem to remember it only showed up
as an external port after I’d connected the Ajays device.


Bruce

I change another platform

it is Dell optiplex 780
and the USB host of b,d,f 0.29.7
work for usb debug.