Re: [PATCH V3 1/4] acpi: Add machine option to disable SPCR table

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Hi Li,

On 15/5/25 14:41, Li Chen wrote:
> From: Li Chen <chenl311@chinatelecom.cn>
> 
> The ACPI SPCR (Serial Port Console Redirection) table allows firmware
> to specify a preferred serial console device to the operating system.
> On ARM64 systems, Linux by default respects this table: even if the
> kernel command line does not include a hardware serial console (e.g.,
> "console=ttyAMA0"), the kernel still register the serial device
> referenced by SPCR as a printk console.
> 
> While this behavior is standard-compliant, it can lead to situations
> where guest console behavior is influenced by platform firmware rather
> than user-specified configuration. To make guest console behavior more
> predictable and under user control, this patch introduces a machine
> option to explicitly disable SPCR table exposure:
> 
>      -machine spcr=off
> 
> By default, the option is enabled (spcr=on), preserving existing
> behavior. When disabled, QEMU will omit the SPCR table from the guest's
> ACPI namespace, ensuring that only consoles explicitly declared in the
> kernel command line are registered.
> 
> Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
> Reviewed-by: Bibo Mao <maobibo@loongson.cn>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> ---


> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 765dc8dd35..089104d54b 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -444,6 +444,7 @@ struct MachineState {
>       SmpCache smp_cache;
>       struct NVDIMMState *nvdimms_state;
>       struct NumaState *numa_state;
> +    bool enable_spcr;

This structure is used by all machines. Can we be more
descriptive, maybe naming as "acpi_spcr_enabled"?

Thanks,

Phil.