Re: [Xen-devel] [PATCH FOR-4.5] xen: arm: Do not enable EFI in dom0 since it is not yet supported.

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 10/14/2014 02:07 PM, Ian Campbell wrote:
> On Tue, 2014-10-14 at 13:58 +0100, Julien Grall wrote:
>> On 10/14/2014 01:49 PM, Ian Campbell wrote:
>>> On Tue, 2014-10-14 at 13:28 +0100, Julien Grall wrote:
>>>> Hi Ian,
>>>>
>>>> On 10/14/2014 08:21 AM, Ian Campbell wrote:
>>>>> On Mon, 2014-10-13 at 12:37 -0700, Roy Franz wrote:
>>>>>> On Mon, Oct 13, 2014 at 9:20 AM, Julien Grall <julien.grall@xxxxxxxxxx> 
>>>>>> wrote:
>>>>>>> (CC vijay)
>>>>>>>
>>>>>>> Hi Suravee,
>>>>>>>
>>>>>>> On 10/13/2014 05:17 PM, suravee.suthikulpanit@xxxxxxx wrote:
>>>>>>>> From: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
>>>>>>>>
>>>>>>>> Since EFI is not yet supported in dom0, we need to remove the following
>>>>>>>> properties from the chosen node:
>>>>>>>>
>>>>>>>>   * linux,uefi-mmap-start
>>>>>>>>   * linux,uefi-mmap-size
>>>>>>>>   * linux,uefi-mmap-desc-size
>>>>>>>>   * linux,uefi-mmap-desc-ver
>>>>>>>>
>>>>>>>> These are added by "arch/arm/efi/efi-boot.h: fdt_add_uefi_nodes()",
>>>>>>>> and used by dom0 kernel to enable EFI.
>>>>>>>>
>>>>>>>> Cc: Julien Grall <julien.grall@xxxxxxxxxx>
>>>>>>>> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>>>>>>>> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
>>>>>>>> Cc: Roy Franz <roy.franz@xxxxxxxxxx>
>>>>>>>> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
>>>>>>>
>>>>>>> Reviewed-by: Julien Grall <julien.grall@xxxxxxxxxx>
>>>>>>
>>>>>> Reviewed-by: Roy Franz <roy.franz@xxxxxxxxxx>
>>>>>
>>>>> Acked-by: Ian Campbell <ian.campbell@.citrix.com>
>>>>>
>>>>> But I do wonder why we don't just drop the hos /chosen node -- I think
>>>>> everything which should be in there is fabricated by the h/visor anyway.
>>>>
>>>> I though about the same things yesterday, but the /chosen node may
>>>> contain other properties (such as OS specific) that we may need to pass
>>>> to DOM0.
>>>
>>> What sort of thing are you thinking of here?
>>
>> FreeBSD provides two properties (stdin and stdout) to choose the input
>> and the output methods.
>>
>> Those properties need to be copied in DOM0 DT to allow the user chose
>> which console he wants to use (think about a platform with 2 serial ports).
> 
> How do you know whether stdin/stdout were intended to apply to dom0 or
> Xen?

We specify the console for Xen via the Xen command line.

> What if dom0 wants to use hvc0? How is that expressed?

For now it has the priority against anything else. But in ideal world,
the HVC console should be describe in a device node add by Xen.

> It seems to me that if bootargs is being consumed by Xen then
> stdin/stdout ought to be consumed by Xen for consistency.

stdin/stdout is part of FreeBSD command line. If we use those
properties, why don't we parse Linux command line to get the console?

> Which points to special handling for stdin/stdout in Xen, i.e. a
> continuation of the whitelisting approach.

And how do you chose the console for DOM0? For Linux we have to use
console=hvc0 on the command line. FreeBSD choose to use stdin/stdout.

Regards,

-- 
Julien Grall

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