Re: [Xen-devel] [PATCH v2 05/10] arm: make it possible to enable/disable UART drivers

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.05.18 at 11:25, <julien.grall@xxxxxxx> wrote:
> On 05/22/2018 10:22 AM, Jan Beulich wrote:
>>>>> On 22.05.18 at 10:51, <julien.grall@xxxxxxx> wrote:
>>> On 05/22/2018 07:34 AM, Jan Beulich wrote:
>>>>>>> Stefano Stabellini <sstabellini@xxxxxxxxxx> 05/22/18 2:53 AM >>>
>>>>> @@ -53,7 +53,8 @@ config HAS_SCIF
>>>>> or Renesas R-Car Gen 2/3 based board say Y.
>>>>    >
>>>>> config HAS_EHCI
>>>>> - bool
>>>>> + bool "EHCI UART driver"
>>>>
>>>> ... here iirc Julien had already pointed out that the drivers should not 
>>>> become
>>>> optional on x86, i.e. in the former case you want to attach a conditional 
>>>> to the
>>>> prompt while in the latter case I don't see why you add the prompt in the 
>>>> first
>>>> place if you mean to make it x86-specific. Which by itself is questionable
>>>> though: Why would this driver be x86-specific, when so far it (consciously)
>>>> hasn't been? If anything I could see it depend on HAS_PCI.
>>>
>>> I don't expect this piece of hardware to come up on Arm.
>> 
>> I can read two meanings into this: You expect the driver to not work on
>> ARM, or you're confident the EHCI protocol of accessing USB host
>> controller hardware not used anywhere in devices used on ARM. Which
>> of the two you mean determines what the correct approach here is.
> 
> I am quite confident the EHCI protocol is not used on Arm.

And why would that be? I thought PCI was universal enough that I could
put basically any card into a system independent of CPU architecture,
perhaps with the exception of such requiring option ROMs but not offering
an EFI Byte Code flavor of that code.

Jan



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