[PATCH] arm/docs: Drop mentioning of ACPI for properties under "hypervisor" node

[PATCH] arm/docs: Drop mentioning of ACPI for properties under "hypervisor" node

[Oleksandr Tyshchenko]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

Remove the following sentence:
"This property is unnecessary when booting Dom0 using ACPI."
for "reg" and "interrupts" properties as the initialization is not
done via device-tree "hypervisor" node in that case anyway.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
---
 docs/misc/arm/device-tree/guest.txt | 2 --
 1 file changed, 2 deletions(-)

diff --git a/docs/misc/arm/device-tree/guest.txt b/docs/misc/arm/device-tree/guest.txt
index c115751..2b974bb 100644
--- a/docs/misc/arm/device-tree/guest.txt
+++ b/docs/misc/arm/device-tree/guest.txt
@@ -15,11 +15,9 @@ the following properties:
   or equal to gnttab_max_grant_frames()).
   Regions 1...N are extended regions (unused address space) for mapping foreign
   GFNs and grants, they might be absent if there is nothing to expose.
-  This property is unnecessary when booting Dom0 using ACPI.
 
 - interrupts: the interrupt used by Xen to inject event notifications.
   A GIC node is also required.
-  This property is unnecessary when booting Dom0 using ACPI.
 
 To support UEFI on Xen ARM virtual platforms, Xen populates the FDT "uefi" node
 under /hypervisor with following parameters:
-- 
2.7.4

Re: [PATCH] arm/docs: Drop mentioning of ACPI for properties under "hypervisor" node

[Stefano Stabellini]

On Thu, 9 Dec 2021, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> Remove the following sentence:
> "This property is unnecessary when booting Dom0 using ACPI."
> for "reg" and "interrupts" properties as the initialization is not
> done via device-tree "hypervisor" node in that case anyway.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> ---
>  docs/misc/arm/device-tree/guest.txt | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/guest.txt b/docs/misc/arm/device-tree/guest.txt
> index c115751..2b974bb 100644
> --- a/docs/misc/arm/device-tree/guest.txt
> +++ b/docs/misc/arm/device-tree/guest.txt
> @@ -15,11 +15,9 @@ the following properties:
>    or equal to gnttab_max_grant_frames()).
>    Regions 1...N are extended regions (unused address space) for mapping foreign
>    GFNs and grants, they might be absent if there is nothing to expose.
> -  This property is unnecessary when booting Dom0 using ACPI.
>  
>  - interrupts: the interrupt used by Xen to inject event notifications.
>    A GIC node is also required.
> -  This property is unnecessary when booting Dom0 using ACPI.
>  
>  To support UEFI on Xen ARM virtual platforms, Xen populates the FDT "uefi" node
>  under /hypervisor with following parameters:
> -- 
> 2.7.4
> 

Re: [PATCH] arm/docs: Drop mentioning of ACPI for properties under "hypervisor" node

[Julien Grall]

Hi Oleksandr,

On 09/12/2021 20:50, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> Remove the following sentence:
> "This property is unnecessary when booting Dom0 using ACPI."
> for "reg" and "interrupts" properties as the initialization is not
> done via device-tree "hypervisor" node in that case anyway.

Why do you think that? On ACPI, the hypervisor node is used to discover 
whether the OS is running on top of Xen (see [1]).

For dom0, Xen will actually create the hypervisor node with the 
compatible property and the uefi bits (see [2]).

The properties "regs" and "interrupts" are not created for ACPI and 
therefore this should be mentioned in the Device-Tree bindings.

> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> ---
>   docs/misc/arm/device-tree/guest.txt | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/docs/misc/arm/device-tree/guest.txt b/docs/misc/arm/device-tree/guest.txt
> index c115751..2b974bb 100644
> --- a/docs/misc/arm/device-tree/guest.txt
> +++ b/docs/misc/arm/device-tree/guest.txt
> @@ -15,11 +15,9 @@ the following properties:
>     or equal to gnttab_max_grant_frames()).
>     Regions 1...N are extended regions (unused address space) for mapping foreign
>     GFNs and grants, they might be absent if there is nothing to expose.
> -  This property is unnecessary when booting Dom0 using ACPI.
>   
>   - interrupts: the interrupt used by Xen to inject event notifications.
>     A GIC node is also required.
> -  This property is unnecessary when booting Dom0 using ACPI.
>   
>   To support UEFI on Xen ARM virtual platforms, Xen populates the FDT "uefi" node
>   under /hypervisor with following parameters:

Cheers,

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/xen/enlighten.c#n253

[2] 
https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/arm/acpi/domain_build.c;h=bbdc90f92c003c0c6d0f0b0290a1776336224719;hb=HEAD#l90

-- 
Julien Grall

Re: [PATCH] arm/docs: Drop mentioning of ACPI for properties under "hypervisor" node

[Oleksandr]

On 10.12.21 11:00, Julien Grall wrote:
> Hi Oleksandr,


Hi Julien


>
> On 09/12/2021 20:50, Oleksandr Tyshchenko wrote:
>> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>>
>> Remove the following sentence:
>> "This property is unnecessary when booting Dom0 using ACPI."
>> for "reg" and "interrupts" properties as the initialization is not
>> done via device-tree "hypervisor" node in that case anyway.
>
> Why do you think that? On ACPI, the hypervisor node is used to 
> discover whether the OS is running on top of Xen (see [1]).
>
> For dom0, Xen will actually create the hypervisor node with the 
> compatible property and the uefi bits (see [2]).
>
> The properties "regs" and "interrupts" are not created for ACPI and 
> therefore this should be mentioned in the Device-Tree bindings.


You are right. I missed that fact. Current patch is not needed in this case.


>
>
>>
>> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>> ---
>>   docs/misc/arm/device-tree/guest.txt | 2 --
>>   1 file changed, 2 deletions(-)
>>
>> diff --git a/docs/misc/arm/device-tree/guest.txt 
>> b/docs/misc/arm/device-tree/guest.txt
>> index c115751..2b974bb 100644
>> --- a/docs/misc/arm/device-tree/guest.txt
>> +++ b/docs/misc/arm/device-tree/guest.txt
>> @@ -15,11 +15,9 @@ the following properties:
>>     or equal to gnttab_max_grant_frames()).
>>     Regions 1...N are extended regions (unused address space) for 
>> mapping foreign
>>     GFNs and grants, they might be absent if there is nothing to expose.
>> -  This property is unnecessary when booting Dom0 using ACPI.
>>     - interrupts: the interrupt used by Xen to inject event 
>> notifications.
>>     A GIC node is also required.
>> -  This property is unnecessary when booting Dom0 using ACPI.
>>     To support UEFI on Xen ARM virtual platforms, Xen populates the 
>> FDT "uefi" node
>>   under /hypervisor with following parameters:
>
> Cheers,
>
> [1] 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/xen/enlighten.c#n253
>
> [2] 
> https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/arm/acpi/domain_build.c;h=bbdc90f92c003c0c6d0f0b0290a1776336224719;hb=HEAD#l90
>
-- 
Regards,

Oleksandr Tyshchenko