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[PATCH v8 06/26] emul/ns16x50: implement SCR register
- To: xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: dmukhin@xxxxxxxx
- Date: Wed, 11 Nov 2026 11:47:40 -0800
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- Cc: andrew.cooper3@xxxxxxxxxx, anthony.perard@xxxxxxxxxx, jbeulich@xxxxxxxx, julien@xxxxxxx, michal.orzel@xxxxxxx, roger@xxxxxxxxxxxxxx, sstabellini@xxxxxxxxxx, xakep.amatop@xxxxxxxxx, dmukhin@xxxxxxx, Denis Mukhin <dmukhin@xxxxxxxx>
- Delivery-date: Wed, 11 Nov 2026 19:48:38 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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From: Denis Mukhin <dmukhin@xxxxxxxx>
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@xxxxxxxx>
---
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 80805ee6ecc6..2371aa32d03f 100644
--- a/xen/common/emul/vuart/ns16x50.c
+++ b/xen/common/emul/vuart/ns16x50.c
@@ -145,6 +145,11 @@ static int ns16x50_io_write8(
/* DLAB=0 */
break;
+ /* NB: Firmware (e.g. OVMF) may rely on SCR presence. */
+ case UART_SCR:
+ regs[UART_SCR] = val;
+ break;
+
default:
rc = -EINVAL;
break;
@@ -234,6 +239,10 @@ static int ns16x50_io_read8(
/* DLAB=0 */
break;
+ case UART_SCR:
+ val = regs[UART_SCR];
+ break;
+
default:
rc = -EINVAL;
break;
--
2.56.0
|
