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

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

> 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


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