[coreboot] USB Debug support

Joseph Smith joe at settoplinux.org
Wed Jul 2 14:08:59 CEST 2008


> -----Original Message-----
> From: coreboot-bounces at coreboot.org [mailto:coreboot-bounces at coreboot.org]
> On Behalf Of Gregg C Levine
> Sent: Wednesday, July 02, 2008 7:45 AM
> To: Coreboot
> Subject: [coreboot] USB Debug support
> Hello!
> Let me see if I understand the thread earlier on USB Debug support.
> A USB cable configured to connect two systems together, such as a laptop
> to
> receive files from a desktop is simply two USB-A cables wired to an
> appropriate logic array. 

Correct but the "appropriate logic array" are two USB device chips talking
to each other so to speak.

> This would (Or "should be". Either way) probably be
> the latest generation in USB Gadget hardware.
> Ideally a Linux system can use this to talk to an appropriately configured
> system, provided the target was built using the debug features turned on
> for the USB stack layer.
Yes there is a kernel driver for this, it just needs to be enabled in the

> While I have here hardware for trying out this idea, namely my Linux
> development station, I have not as yet chosen a target.
You just have to make sure the EHCI USB device on the southbridge supports
USB debugging and is enabled in the PCI config space.
In the next 6 months (projected timeframe) I will be working on a HOWTO
build your own USB debug cable. I have much reading and studying to do first
though. Hope that helps.

Joseph Smith

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