Re: [Qemu-devel] [PATCH v2 3/5] acpi: pc: add fw_cfg device node to ssdt

[Eduardo Habkost]

On Mon, Sep 14, 2015 at 10:57:31AM -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 <address@hidden>
> ---
>  hw/i386/acpi-build.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 95e0c65..ecdb3a5 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1071,6 +1071,26 @@ build_ssdt(GArray *table_data, GArray *linker,
>      aml_append(scope, aml_name_decl("_S5", pkg));
>      aml_append(ssdt, scope);
>  
> +    if (guest_info->fw_cfg) {

I sent a reply to v1 a few minutes before seeing v2. Copying it here for
reference:

Is this function ever going to be called without fw_cfg set?
acpi_setup() returns immediately if fw_cfg isn't available.

Also, this changes guest ABI, so you will need to add some compat flag
to PCMachineClass indicating if the device node should be added.


> +        scope = aml_scope("\\_SB");
> +        dev = aml_device("FWCF");
> +
> +        aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
> +
> +        crs = aml_resource_template();
> +        /* when using port i/o, the 8-bit data register *always* overlaps
> +         * with half of the 16-bit control register. Hence, the total size
> +         * of the i/o region used is FW_CFG_CTL_SIZE */
> +        aml_append(crs,
> +            aml_io(AML_DECODE16, FW_CFG_IO_BASE, FW_CFG_IO_BASE,
> +                   0x01, FW_CFG_CTL_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
> 

-- 
Eduardo