add to acpi table

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 34 insertions, 22 deletions

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 83ae739a12..de9b98029a 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -77,11 +77,11 @@ static void acpi_dsdt_add_cpus(Aml *scope, VirtMachineState *vms)
 }
 
 static void acpi_dsdt_add_uart(Aml *scope, const MemMapEntry *uart_memmap,
-                                           uint32_t uart_irq)
+                               uint32_t uart_irq, int uartidx)
 {
-    Aml *dev = aml_device("COM0");
+    Aml *dev = aml_device("COM%d", uartidx);
     aml_append(dev, aml_name_decl("_HID", aml_string("ARMH0011")));
-    aml_append(dev, aml_name_decl("_UID", aml_int(0)));
+    aml_append(dev, aml_name_decl("_UID", aml_int(uartidx)));
 
     Aml *crs = aml_resource_template();
     aml_append(crs, aml_memory32_fixed(uart_memmap->base,
@@ -860,7 +860,11 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     scope = aml_scope("\\_SB");
     acpi_dsdt_add_cpus(scope, vms);
     acpi_dsdt_add_uart(scope, &memmap[VIRT_UART0],
-                       (irqmap[VIRT_UART0] + ARM_SPI_BASE));
+                       (irqmap[VIRT_UART0] + ARM_SPI_BASE), 0);
+    if (vms->second_uart_present) {
+        acpi_dsdt_add_uart(scope, &memmap[VIRT_UART1],
+                           (irqmap[VIRT_UART1] + ARM_SPI_BASE), 1);
+    }
     if (vmc->acpi_expose_flash) {
         acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH]);
     }
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index a036d3fa76..63dbfb937a 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -857,21 +857,9 @@ static void create_uart(const VirtMachineState *vms, int uart,
                         MemoryRegion *mem, Chardev *chr)
 {
     char *nodename;
-    /*
-     * The first UART always always exists. If the security extensions are
-     * enabled, the second UART also always exists. Otherwise, it only exists
-     * if a backend is configured explicitly via '-serial <backend>', where
-     * 'null' creates a dummy backend. This allows enabling the second UART
-     * explicitly on demand and does not interfere with any existing setup that
-     * just expect one (or two if security extensions are enabled) UARTs.
-     */
     switch(uart) {
     case VIRT_UART0:
-        break;
     case VIRT_UART1:
-        if (!vms->secure && !chr) {
-            return;
-        }
         break;
     default:
         error_report("unsupported UART ID %d", uart);
@@ -2301,17 +2289,36 @@ static void machvirt_init(MachineState *machine)
     fdt_add_pmu_nodes(vms);
 
     /*
-     * These end up in the DTB in reverse order of creation, so
-     * we must create UART0 last to ensure it appears as the
-     * first TTYAMA0 for Linux.
-     * For back-compatibility, if UART1 is the secure UART and
-     * thus always created, we create it second.
+     * The first UART always always exists. If the security extensions are
+     * enabled, the second UART also always exists. Otherwise, it only exists
+     * if a backend is configured explicitly via '-serial <backend>', where
+     * 'null' creates a dummy backend. This allows enabling the second UART
+     * explicitly on demand and does not interfere with any existing setup that
+     * just expect one (or two if security extensions are enabled) UARTs.
+     *
+     * The nodes end up in the DTB in reverse order of creation, so we must
+     * create UART0 last to ensure it appears as the first node in the DTB,
+     * for compatibility with guest software that just iterates through the
+     * DTB to find the first UART, as older versions of EDK2 do.
+     * DTB readers that follow the spec, as Linux does, should honour the
+     * aliases node information and /chosen/stdout-path regardless of
+     * the order that nodes appear in the DTB.
+     *
+     * For similar back-compatibility reasons, if UART1 is the secure UART
+     * we create it second (and so it appears first in the DTB), because
+     * that's what QEMU has always done.
      */
     if (!vms->secure) {
-        create_uart(vms, VIRT_UART1, sysmem, serial_hd(1));
+        Chardev *serial1 = serial_hd(1);
+
+        if (serial1) {
+            vms->second_uart_present = true;
+            create_uart(vms, VIRT_UART1, sysmem, serial1);
+        }
     }
     create_uart(vms, VIRT_UART0, sysmem, serial_hd(0));
     if (vms->secure) {
+        vms->second_uart_present = true;
         create_uart(vms, VIRT_UART1, secure_sysmem, serial_hd(1));
     }
 
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index ddad477d50..3628c532cb 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -160,6 +160,7 @@ struct VirtMachineState {
     bool ras;
     bool mte;
     bool dtb_randomness;
+    bool second_uart_present;
     OnOffAuto acpi;
     VirtGICType gic_version;
     VirtIOMMUType iommu;