Re: [Xen-devel] [GSOC-2019] Problem with initializing crossbar on bb-x15 in dom0

[Julien Grall <Julien.Grall@xxxxxxx>]

On 06/07/2019 17:31, Denis Obrezkov wrote:
> Hi,

Hi Denis,

> 
> On 7/6/19 5:57 PM, Julien Grall wrote:
>>
> 
>>
>>       rc = unmap_mmio_regions(d, _gfn(pfn_start),
>>                               pfn_end + pfn_start + 1,
>>                               _mfn(pfn_start));
>>
>> You are not computing correctly the number of pages. I think you want
>> "pfn_end - pfn_start + 1".
> Ok, I changed it and was able to boot to the previous error. I think a
> logical next step would be to set up the uart somehow?

Do you mean the UART used by Xen?

>>
>> But this feels weird to map then unmap the mmio. Instead, you should
>> blacklist the crossbar device. Have a look at the field blacklist_dev in
>> platform_desc.
> Hm, I can see that in the device tree the crossbar has a phandle
> property <0x00000008> and the main node has an interrupt-parent property
> 0x00000008. So, all the interrupts seems to be mapped to the crossbar.
> Wouldn't be that a problem if we blacklist the device?


The Device is owned by Xen, so technically Dom0 does not see the 
hardware one. Instead it sees a virtual and therefore the node should be 
created to reflect it.

The purpose of recreating the node is you can alter it to match what we 
actually exposed to the domain (property values may differ). It may 
happen that a lot of information are exactly the same as the hardware 
and can just be copied.

This is, for instance, what we do for the GIC and timer.

> Also, the tegra
> implementation blacklist only a uart.

I don't understand this.

Cheers,

-- 
Julien Grall
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