From: Xiaoyao Li <xiaoyao...@intel.com>
A value 1 of PCAT_COMPAT (bit 0) of MADT.Flags indicates that the system
also has a PC-AT-compatible dual-8259 setup, i.e., the PIC. When PIC
is not enabled (pic=off) for x86 machine, the PCAT_COMPAT bit needs to
be cleared. The PIC probe should then print:
[ 0.155970] Using NULL legacy PIC
However, no such log printed in guest kernel unless PCAT_COMPAT is
cleared.
Signed-off-by: Xiaoyao Li <xiaoyao...@intel.com>
Message-ID: <20240403145953.3082491-1-xiaoyao...@intel.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
hw/i386/acpi-common.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/hw/i386/acpi-common.c b/hw/i386/acpi-common.c
index 20f19269da4..0cc2919bb85 100644
--- a/hw/i386/acpi-common.c
+++ b/hw/i386/acpi-common.c
@@ -107,7 +107,9 @@ void acpi_build_madt(GArray *table_data, BIOSLinker *linker,
acpi_table_begin(&table, table_data);
/* Local APIC Address */
build_append_int_noprefix(table_data, APIC_DEFAULT_ADDRESS, 4);
- build_append_int_noprefix(table_data, 1 /* PCAT_COMPAT */, 4); /* Flags */
+ /* Flags. bit 0: PCAT_COMPAT */
+ build_append_int_noprefix(table_data,
+ x86ms->pic != ON_OFF_AUTO_OFF ? 1 : 0 , 4);
for (i = 0; i < apic_ids->len; i++) {
pc_madt_cpu_entry(i, apic_ids, table_data, false);
--
2.44.0
