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

["Michael S. Tsirkin" <mst@redhat.com>]

On Sat, Sep 12, 2015 at 07:30:41PM -0400, Gabriel L. Somlo wrote:
> 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")));

Generally that's an illegal HID. If this device has a driver,
use QEMU as a prefix. Otherwise, use one of the pre-defined ones
with a PNP ISA ID.

> +        /* 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