x86: q35: generate WDAT ACPI table
It will generate WDAT table [1] customized for TCO watchdog. This allows Windows guests (Windows Server 2008/Vista+) to use TCO watchdog using built-in generic driver, which alleviates need to install vendor specific drivers. Given that enabling it might change guest behaviour (both Windows/Linux) the feature is disabled by default. Users that need it can enable the feature with following CLI option. -machine wdat=on 1) "Hardware Watchdog Timers Design Specification" https://uefi.org/acpi 'Watchdog Action Table (WDAT)' Signed-off-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Ani Sinha <anisinha@redhat.com> Reviewed-by: Zhao Liu <zhao1.liu@intel.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Message-Id: <20260303092532.2410177-4-imammedo@redhat.com>
Igor Mammedov committed
Mar 3, 2026 at 10:25 UTC
f7060ac4e7dda3edc6153356c6d665f27847368c
5 files changed
+134
-1
hw/acpi/meson.build
+2
-1
@@ -25,7 +25,8 @@ acpi_ss.add(when: 'CONFIG_ACPI_PCI_BRIDGE', if_true: files('pci-bridge.c'))
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acpi_ss.add(when: 'CONFIG_ACPI_PCIHP', if_true: files('pcihp.c'))
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stub_ss.add(files('acpi-pci-hotplug-stub.c'))
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acpi_ss.add(when: 'CONFIG_ACPI_VIOT', if_true: files('viot.c'))
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-acpi_ss.add(when: 'CONFIG_ACPI_ICH9', if_true: files('ich9.c', 'ich9_tco.c', 'ich9_timer.c'))
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+acpi_ss.add(when: 'CONFIG_ACPI_ICH9', if_true: files('ich9.c', 'ich9_tco.c', 'ich9_timer.c', 'wdat-ich9.c'))
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+stub_ss.add(files('wdat-ich9-stub.c'))
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acpi_ss.add(when: 'CONFIG_ACPI_ERST', if_true: files('erst.c'))
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acpi_ss.add(when: 'CONFIG_IPMI', if_true: files('ipmi.c'))
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stub_ss.add(files('ipmi-stub.c'))
hw/acpi/wdat-ich9-stub.c
new
+15
@@ -0,0 +1,15 @@
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+/*
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+ * Copyright Red Hat, Inc. 2026
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+ * Author(s): Igor Mammedov <imammedo@redhat.com>
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+ *
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+ * SPDX-License-Identifier: GPL-2.0-or-later
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+ */
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+
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+#include "qemu/osdep.h"
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+#include "hw/acpi/wdat-ich9.h"
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+
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+void build_ich9_wdat(GArray *table_data, BIOSLinker *linker, const char *oem_id,
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+ const char *oem_table_id, uint64_t tco_base)
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+{
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+ g_assert_not_reached();
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+}
hw/acpi/wdat-ich9.c
new
+90
@@ -0,0 +1,90 @@
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+/*
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+ * TCO Watchdog Action Table (WDAT)
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+ *
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+ * Copyright Red Hat, Inc. 2026
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+ * Author(s): Igor Mammedov <imammedo@redhat.com>
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+ *
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+ * SPDX-License-Identifier: GPL-2.0-or-later
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+ */
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+
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+#include "qemu/osdep.h"
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+#include "hw/acpi/wdat.h"
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+#include "hw/acpi/wdat-ich9.h"
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+#include "hw/southbridge/ich9.h"
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+
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+#define TCO_REG(base, reg_offset, reg_width) { .space_id = AML_AS_SYSTEM_IO, \
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+ .address = base + reg_offset, .bit_width = reg_width, \
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+ .access_width = AML_WORD_ACC, };
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+
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+/*
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+ * "Hardware Watchdog Timers Design Specification"
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+ * https://uefi.org/acpi 'Watchdog Action Table (WDAT)'
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+ *
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+ * ICH9 specific implementation.
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+ */
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+void build_ich9_wdat(GArray *table_data, BIOSLinker *linker, const char *oem_id,
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+ const char *oem_table_id, uint64_t tco_base)
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+{
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+ AcpiTable table = { .sig = "WDAT", .rev = 1, .oem_id = oem_id,
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+ .oem_table_id = oem_table_id };
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+ struct AcpiGenericAddress tco_rld = TCO_REG(tco_base, 0x0, 16);
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+ struct AcpiGenericAddress tco2_sts = TCO_REG(tco_base, 0x6, 16);
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+ struct AcpiGenericAddress tco1_cnt = TCO_REG(tco_base, 0x8, 16);
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+ struct AcpiGenericAddress tco_tmr = TCO_REG(tco_base, 0x12, 16);
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+
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+ acpi_table_begin(&table, table_data);
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+ build_append_int_noprefix(table_data, 0x20, 4); /* Watchdog Header Length */
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+ build_append_int_noprefix(table_data, 0xff, 2); /* PCI Segment */
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+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Bus Number */
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+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Device Number */
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+ build_append_int_noprefix(table_data, 0xff, 1); /* PCI Function Number */
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+ build_append_int_noprefix(table_data, 0, 3); /* Reserved */
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+ /*
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+ * limits/resolution are defined by ICH9 TCO spec
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+ */
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+ build_append_int_noprefix(table_data, 0x258, 4);/* Timer Period, ms */
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+ build_append_int_noprefix(table_data, 0x3ff, 4);/* Maximum Count */
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+ build_append_int_noprefix(table_data, 0x4, 4); /* Minimum Count */
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+ /*
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+ * WATCHDOG_ENABLED & WATCHDOG_STOPPED_IN_SLEEP_STATE
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+ */
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+ build_append_int_noprefix(table_data, 0x81, 1); /* Watchdog Flags */
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+ build_append_int_noprefix(table_data, 0, 3); /* Reserved */
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+ /*
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+ * watchdog instruction entries
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+ */
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+ build_append_int_noprefix(table_data, 10 /* # of actions below */, 4);
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+ /* Action table */
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+ build_append_wdat_ins(table_data, WDAT_ACTION_RESET,
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+ WDAT_INS_WRITE_VALUE,
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+ tco_rld, 0x1, 0x1ff);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_RUNNING_STATE,
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+ WDAT_INS_READ_VALUE,
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+ tco1_cnt, 0x0, 0x800);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_RUNNING_STATE,
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+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
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+ tco1_cnt, 0, 0x800);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_STOPPED_STATE,
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+ WDAT_INS_READ_VALUE,
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+ tco1_cnt, 0x800, 0x800);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_STOPPED_STATE,
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+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
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+ tco1_cnt, 0x800, 0x800);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_COUNTDOWN_PERIOD,
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+ WDAT_INS_WRITE_COUNTDOWN,
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+ tco_tmr, 0x0, 0x3FF);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_COUNTDOWN_PERIOD,
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+ WDAT_INS_READ_COUNTDOWN,
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+ tco_tmr, 0x0, 0x3FF);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_QUERY_WATCHDOG_STATUS,
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+ WDAT_INS_READ_VALUE,
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+ tco2_sts, 0x2, 0x2);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_WATCHDOG_STATUS,
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+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
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+ tco2_sts, 0x2, 0x2);
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+ build_append_wdat_ins(table_data, WDAT_ACTION_SET_WATCHDOG_STATUS,
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+ WDAT_INS_WRITE_VALUE | WDAT_INS_PRESERVE_REGISTER,
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+ tco2_sts, 0x4, 0x4);
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+
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+ acpi_table_end(linker, &table);
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+}
hw/i386/acpi-build.c
+12
@@ -78,6 +78,7 @@
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#include "hw/acpi/hmat.h"
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#include "hw/acpi/viot.h"
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+#include "hw/acpi/wdat-ich9.h"
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#include CONFIG_DEVICES
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@@ -110,6 +111,7 @@ typedef struct AcpiPmInfo {
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uint16_t cpu_hp_io_base;
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uint16_t pcihp_io_base;
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uint16_t pcihp_io_len;
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+ uint64_t tco_io_base;
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} AcpiPmInfo;
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typedef struct AcpiMiscInfo {
@@ -204,6 +206,7 @@ static void acpi_get_pm_info(MachineState *machine, AcpiPmInfo *pm)
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pm->pcihp_io_len = 0;
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pm->smi_on_cpuhp = false;
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pm->smi_on_cpu_unplug = false;
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+ pm->tco_io_base = 0;
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assert(obj);
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init_common_fadt_data(machine, obj, &pm->fadt);
@@ -225,6 +228,8 @@ static void acpi_get_pm_info(MachineState *machine, AcpiPmInfo *pm)
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!!(smi_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOTPLUG_BIT));
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pm->smi_on_cpu_unplug =
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!!(smi_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT));
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+ pm->tco_io_base = object_property_get_uint(obj, ACPI_PM_PROP_PM_IO_BASE,
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+ NULL) + ICH9_PMIO_TCO_RLD;
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}
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pm->pcihp_io_base =
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object_property_get_uint(obj, ACPI_PCIHP_IO_BASE_PROP, NULL);
@@ -2078,6 +2083,13 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
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acpi_add_table(table_offsets, tables_blob);
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build_waet(tables_blob, tables->linker, x86ms->oem_id, x86ms->oem_table_id);
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+ if (pcms->wdat_enabled == true) {
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+ g_assert(pm.tco_io_base);
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+ acpi_add_table(table_offsets, tables_blob);
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+ build_ich9_wdat(tables_blob, tables->linker, x86ms->oem_id,
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+ x86ms->oem_table_id, pm.tco_io_base);
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+ }
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+
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/* Add tables supplied by user (if any) */
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for (u = acpi_table_first(); u; u = acpi_table_next(u)) {
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unsigned len = acpi_table_len(u);
include/hw/acpi/wdat-ich9.h
new
+15
@@ -0,0 +1,15 @@
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+/*
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+ * Copyright Red Hat, Inc. 2026
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+ * Author(s): Igor Mammedov <imammedo@redhat.com>
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+ *
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+ * SPDX-License-Identifier: GPL-2.0-or-later
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+ */
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+#ifndef QEMU_HW_ACPI_WDAT_ICH9_H
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+#define QEMU_HW_ACPI_WDAT_ICH9_H
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+
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+#include "hw/acpi/aml-build.h"
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+
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+void build_ich9_wdat(GArray *table_data, BIOSLinker *linker, const char *oem_id,
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+ const char *oem_table_id, uint64_t tco_base);
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+
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+#endif /* QEMU_HW_ACPI_WDAT_ICH9_H */