[elrepo] CentOS/Kernel 3.18/Thunderbolt2

[Alan Bartlett]

On 26 January 2015 at 22:54, Israel Brewster <israel at ravnalaska.net> wrote:
> On Jan 26, 2015, at 11:58 AM, Alan Bartlett <ajb at elrepo.org> wrote:
>>
>> Hmm . . . I've taken a look at the Kconfig file and the section
>> relevant to the kernel configuration that references "Thunderbolt"
>> reads as follows --
>>
>> [quote]
>> menuconfig THUNDERBOLT
>>    tristate "Thunderbolt support for Apple devices"
>>    depends on PCI
>>    select CRC32
>>    help
>>      Cactus Ridge Thunderbolt Controller driver
>>      This driver is required if you want to hotplug Thunderbolt devices on
>>      Apple hardware.
>>
>>      Device chaining is currently not supported.
>>
>>      To compile this driver a module, choose M here. The module will be
>>      called thunderbolt.
>> [/quote]
>>
>> The references to "Apple devices" and "Apple hardware" makes me think
>> that is not the correct configuration choice.
>>
>> I can certainly "turn it on", as a module but I have my doubts as to
>> whether it will help.
>
> It looks like you might be right, but perhaps not for the reasons you were thinking. The key phrase in this information, to my mind, is: "Cactus Ridge Thunderbolt Controller driver". Cactus Ridge is the code name for Intel's Thunderbolt controllers that accompanied Ivy Bridge systems (http://ark.intel.com/products/codename/57097/Cactus-Ridge). It's *possible* that that specific chip was only used in Apple hardware (certainly Apple hardware is the primary user of thunderbolt controllers), but I don't know of any reason why that would be the case *necessarily*.
>
> That said, the chip in my system (and, in fact, any thunderbolt 2 system I am aware of at the moment) is a "Falcon Ridge" controller, released Q3 2013 according to the Wikipedia article. As such, I also have my doubts that the "Cactus Ridge" controller driver will help. It's possible the Linux kernel simply doesn't support thunderbolt 2 (yet?).
>
> On the other hand, there is this: http://permalink.gmane.org/gmane.linux.kernel/1717419 which seems to indicate a patch to make things work with the Falcon Ridge controller was available back in June of last year. I think. It also references Apple hardware, but the controller is the same. And this: http://www.gossamer-threads.com/lists/linux/kernel/1935522 which seems to indicate that simply adding some ID's to the Cactus Ridge driver makes it work with thunderbolt2 (Falcon Ridge) controllers - so perhaps the help simply hasn't been updated?
>
> I suppose, however, that it is also possible that if I want to use the thunderbolt card, I'll have to run windows. Which would stink. Maybe there is a Linux kernel mailing list I should be asking on?

The more I look, the more it seems to be a somewhat "oddball" device
interface. A short while ago I was passed a link to a web page [4] by
Greg Kroah-Hartman.

As for a mailing list for all things kernel, I can point you to the
Linux Kernel Mailing List. [5]

Alan.

[4] http://www.kroah.com/log/linux/
[5] https://lkml.org/