[Qemu-devel] [RFC PATCH 2/3] acpi: pc: add fw_cfg device node to ssdt

["Gabriel L. Somlo" <somlo@cmu.edu>]

Add a fw_cfg device node to the ACPI SSDT. While the guest-side
BIOS can't utilize this information (since it has to access the
hard-coded fw_cfg device to extract ACPI tables to begin with),
having fw_cfg listed in ACPI will help the guest kernel keep a
more accurate inventory of in-use IO port regions.

Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
---
 hw/i386/acpi-build.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 95e0c65..9d0ec22 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1071,6 +1071,25 @@ build_ssdt(GArray *table_data, GArray *linker,
     aml_append(scope, aml_name_decl("_S5", pkg));
     aml_append(ssdt, scope);
 
+    if (guest_info->fw_cfg) {
+        scope = aml_scope("\\_SB");
+        dev = aml_device("FWCF");
+
+        aml_append(dev, aml_name_decl("_HID", aml_string("FWCF0001")));
+        /* device present, functioning, decoding, not shown in UI */
+        aml_append(dev, aml_name_decl("_STA", aml_int(0xB)));
+
+        crs = aml_resource_template();
+        aml_append(crs,
+            aml_io(AML_DECODE16, FW_CFG_IO_BASE, FW_CFG_IO_BASE,
+                   0x01, FW_CFG_IO_SIZE)
+        );
+        aml_append(dev, aml_name_decl("_CRS", crs));
+
+        aml_append(scope, dev);
+        aml_append(ssdt, scope);
+    }
+
     if (misc->applesmc_io_base) {
         scope = aml_scope("\\_SB.PCI0.ISA");
         dev = aml_device("SMC");
-- 
2.4.3