Hi Denis,
Thank you for the patch.
On Tue, Sep 9, 2025 at 12:12 AM <dmukhin@xen.org> wrote:
>
> From: Denis Mukhin <dmukhin@ford.com>
>
> Add SCR register emulation to the I/O port handler.
> Firmware (e.g. OVMF) may use SCR during the guest OS boot.
>
> Signed-off-by: Denis Mukhin <dmukhin@ford.com>
> ---
> Changes since v6:
> - default handling of non-DLL/DLM registers moved to the previous patch
> ---
> xen/common/emul/vuart/ns16x50.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/xen/common/emul/vuart/ns16x50.c b/xen/common/emul/vuart/ns16x50.c
> index da8583a1dc93..5643ef4cc01e 100644
> --- a/xen/common/emul/vuart/ns16x50.c
> +++ b/xen/common/emul/vuart/ns16x50.c
> @@ -106,6 +106,11 @@ static int ns16x50_io_write8(
> {
> switch ( reg )
> {
> + /* NB: Firmware (e.g. OVMF) may rely on SCR presence. */
> + case UART_SCR:
> + regs[UART_SCR] = val;
> + break;
> +
> default:
> rc = -EINVAL;
> break;
> @@ -177,6 +182,10 @@ static int ns16x50_io_read8(
> {
> switch ( reg )
> {
> + case UART_SCR:
> + val = regs[UART_SCR];
> + break;
> +
> default:
> rc = -EINVAL;
> break;
> --
> 2.51.0
>
>
Reviewed-by: Mykola Kvach <mykola_kvach@epam.com>
Best regards,
Mykola