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

[dmkhn@proton.me]

Hi Michal,

On Wed, Jun 25, 2025 at 09:07:48AM +0200, Orzel, Michal wrote:
> 
> 
> On 24/06/2025 09:14, dmkhn@proton.me wrote:
> > On Tue, Jun 24, 2025 at 08:37:22AM +0200, Orzel, Michal wrote:
> >>
> >>
> >> On 24/06/2025 05:55, dmkhn@proton.me wrote:
> >>> From: Denis Mukhin <dmukhin@ford.com>
> >>>
> >>> 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@ford.com>
> >>> ---
> >>>  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.

OK, I'll keep hwdom, hope there will be no need to change it again.

I think dtuart may be useful for bringing up some exotic OSes which do
not have pl011 driver.

But then, I want to do s/HWDOM_VUART/VUART_HWDOM/g so all vUART build-time settings
have the same naming convention:
    VUART_SBSA
    VUART_NS16550

Will that be OK with you?

--
Denis

> 
> ~Michal
>