Re: [MirageOS-devel] Writing to Multiple Serial Ports

[Paul Skentzos <paul.skentzos@xxxxxxxxxxxxxxx>]

On 10/20/2015 1:52 PM, Anil Madhavapeddy wrote:
> 
>> On 7 Oct 2015, at 18:25, Paul Skentzos <Paul.Skentzos@xxxxxxxxxxxxxxx> wrote:
>>
>> Anil,
>>
>> On 10/7/2015 12:36 PM, Anil Madhavapeddy wrote:
>>> On 7 Oct 2015, at 15:53, Paul Skentzos <paul.skentzos@xxxxxxxxxxxxxxx> 
>>> wrote:
>>>>
>>>> Hi Luke,
>>>>
>>>> On 10/7/2015 10:15 AM, Luke Dunstan wrote:
>>>>> Hi Paul,
>>>>>
>>>>> Did you get serial ports working even in dom0 on Cubietruck yet? It took 
>>>>> me
>>>>> quite a while to discover that Xen normally disables the A20 UARTs by 
>>>>> deleting
>>>>> them from the device tree:
>>>>>
>>>>> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/arm/platforms/sunxi.c;h=0ba7b3d9b476a95edb653e120b7b3900a47f7c06;hb=HEAD#l64
>>>>>
>>>>> Luke
>>>>>
>>>>
>>>> Yes, we do have this working. It was a bit of an annoyance that we 
>>>> discovered
>>>> just as you did when starting to work on the Cubietruck.
>>>>
>>>> We found that all serial ports with the "snps,dw-apb-uart" driver are
>>>> blacklisted on the "sunxi" platform to prevent dom0 from having driver 
>>>> access to
>>>> the Xen console.  So we hacked up the attached patch.  Which is not an 
>>>> ideal
>>>> fix, but it was good enough for now.
>>>>
>>>> The better fix would be to have Xen compare the memory address for every 
>>>> item in
>>>> the device tree against the addresses that Xen has already reserved for 
>>>> itself.
>>>
>>> We could apply this patch to the https://github.com/mirage/xen-arm-builder
>>> distribution, which is only really used to boot on Cubieboards at the 
>>> moment.
>>> It's nice to have the out-of-the-box experience just work for that 
>>> distribution.
>>>
>>> -anil
>>>
>>>
>>
>> I agree!
>>
>> Would you apply the patch as is or would you like us to formally submit the
>> patch through the mailing list?
> 
> Hi Paul,
> 
> The best way to get the patch into the repository is by submitting a GitHub 
> Pull Request.  This ensures that the provenance of the patch is tracked 
> correctly as coming from you in the history (we can do this via the mailing 
> list as well, but the web interface is easier).
> 
> The relevant scripts in there that clone and build xen are in 
> https://github.com/mirage/xen-arm-builder in the clone-repos.sh script and 
> then build-xen.sh.  You can either apply the patch above in this repo 
> directly if you wish.
> 
> Let me know if you have any questions about the GitHub PR process.
> 
> regards,
> Anil
> 

Anil,

We've sent a pull request to the https://github.com/mirage/xen-arm-builder repo
from https://github.com/dornerworks/xen-arm-builder. Let us know if things look
OK and if there is anything else we need to do to close it out from our end.

Thanks for the guidance!

Paul

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