Re: [PATCH v1 07/16] arm/vuart: rename 'virtual UART' Kconfig option

["Orzel, Michal" <michal.orzel@xxxxxxx>]

On 24/06/2025 09:14, dmkhn@xxxxxxxxx wrote:
> On Tue, Jun 24, 2025 at 08:37:22AM +0200, Orzel, Michal wrote:
>>
>>
>> On 24/06/2025 05:55, dmkhn@xxxxxxxxx wrote:
>>> From: Denis Mukhin <dmukhin@xxxxxxxx>
>>>
>>> Rename HWDOM_VUART to HAS_VUART_MMIO.
>>>
>>> This emulator emulates only one register and the use of the emulator is
>>> limited to early boot console in the guest OS.
>>>
>>> No functional change.
>>>
>>> Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
>>> ---
>>>  xen/arch/arm/Kconfig              | 2 +-
>>>  xen/arch/arm/Makefile             | 2 +-
>>>  xen/arch/arm/include/asm/domain.h | 2 +-
>>>  xen/arch/arm/vuart.h              | 4 ++--
>>>  4 files changed, 5 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
>>> index 03888569f38c..b11cb583a763 100644
>>> --- a/xen/arch/arm/Kconfig
>>> +++ b/xen/arch/arm/Kconfig
>>> @@ -177,7 +177,7 @@ config HAS_VUART_PL011
>>>       Allows a guest to use SBSA Generic UART as a console. The
>>>       SBSA Generic UART implements a subset of ARM PL011 UART.
>>>
>>> -config HWDOM_VUART
>>> +config HAS_VUART_MMIO
>> I personally don't like this change. The current config option name reads 
>> much
>> better and clearly denotes the purpose.
> 
> In my opinion, the MMIO-based UART is a useful debugging tool for early guest
> boot, even when the guest doesn't run in hwdom or on Arm system.
The reason why this vUART is for hwdom is that is uses information from dtuart
(physical UART used by Xen probed from DT). This is to enable kernels used as
dom0 that had early printk/earlycon set for this serial device (as if they run
baremetal). Regular domUs have vPL011 and don't need hwdom vUART.

~Michal