Re: [discuss] Re: kgdb for x86_64 2.6 kernels

George Anzinger
2004-01-15T03:31:08Z

Greg KH wrote:
> On Wed, Jan 14, 2004 at 04:02:45PM -0800, George Anzinger wrote:
>
>>Greg KH wrote:
>>
>>>On Wed, Jan 14, 2004 at 12:02:02PM -0800, George Anzinger wrote:
>>>
>>>
>>>>Right. I had hoped that we might one day be able to use the USB and I am
>>>>sure there are others.
>>>
>>>
>>>Raw USB? Or some kind of USB to serial device?
>>>
>>>Remember, USB needs interrupts to work, see the kdb patches for the mess
>>>that people have tried to go through to send usb data without interrupts
>>>(doesn't really work...)
>>
>>I gave up on USB when I asked the following questions:
>>1. How many different HW USB master devices need to be supported (i.e.
>>appear on your normal line of MBs)? (answer, too many)
>
>
> There are only 3, UHCI, OHCI, and EHCI. You can forget about EHCI, as
> all EHCI controllers contain either a UHCI or OHCI controller embedded
> in them (EHCI only handles the USB2 high speed data.) So you really
> only have to handle 2.
>
>
>>2. Can I isolate a USB port from the kernel so that it does not even know
>>it is there? (answer: NO)
>
>
> Sorry, this is correct. Unless you want to take over the whole pci
> device that the USB controller is on. That's a possiblity you might
> want to look into.

Each cpu, usually, has several USB controllers. I would only want to take over
one. Is that possible? If not, it means we can not debug USB drivers...

--
George Anzinger george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml