Re: [Qemu-devel] [PATCH v7 3/5] acpi: pc: add fw_cfg device node to ssdt

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 10 Feb 2016 15:41:38 -0500
"Gabriel L. Somlo" <somlo@cmu.edu> wrote:

> Add a fw_cfg device node to the ACPI SSDT. While the guest-side
> firmware 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.
subj and commit msg:
s/SSDT/DSDT/

> 
> Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
> Reviewed-by: Marc Marí <markmb@redhat.com>
> ---
>  hw/i386/acpi-build.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 4554eb8..4762fd2 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -2190,6 +2190,35 @@ build_dsdt(GArray *table_data, GArray *linker,
>      aml_append(scope, aml_name_decl("_S5", pkg));
>      aml_append(dsdt, scope);
>  
> +    /* create fw_cfg node, unconditionally */
Will that unconditionally make all Windows guests ask for driver for unknown device?


> +    {
> +        /* 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; when using DMA, the
> +         * DMA control register is located at FW_CFG_DMA_IO_BASE + 4 */
> +        uint8_t io_size = object_property_get_bool(OBJECT(pcms->fw_cfg),
> +                                                   "dma_enabled", NULL) ?
> +                          ROUND_UP(FW_CFG_CTL_SIZE, 4) + sizeof(dma_addr_t) :
> +                          FW_CFG_CTL_SIZE;
> +
> +        scope = aml_scope("\\_SB");
> +        dev = aml_device("FWCF");
> +
> +        aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
> +
> +        /* 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, io_size)
> +        );
> +        aml_append(dev, aml_name_decl("_CRS", crs));
> +
> +        aml_append(scope, dev);
> +        aml_append(dsdt, scope);
> +    }
> +
>      if (misc->applesmc_io_base) {
>          scope = aml_scope("\\_SB.PCI0.ISA");
>          dev = aml_device("SMC");