Re: [SeaBIOS] [PATCHv3] acpi: make default DSDT optional

[Kevin O'Connor]

On Mon, Mar 18, 2013 at 01:00:42PM +0200, Michael S. Tsirkin wrote:
> Since commit f7e4dd6c18ccfbaf6cd2f5eaaed2b77cabc8a406 QEMU loads its
> own copy of DSDT, so let's not build in PIIX.  This makes building in
> the DSDT an option, default to on (built-in).
> For the builds bundled with qemu (where we _know_ qemu is
> new enougth that it actually works) we can flip the switch to 'n' (via
> roms/config.seabios).  This way we save some space in the rom file and make
> it easy to avoid shipping dead code in qemu.  At some point we might
> be able to switch it off by default and then maybe remove altogether.
>
> With CONFIG_ACPI_DSDT = y
> Total size: 127348  Fixed: 58892  Free: 3724 (used 97.2% of 128KiB rom)
> With CONFIG_ACPI_DSDT = n
> Total size: 122844  Fixed: 58884  Free: 8228 (used 93.7% of 128KiB rom)

Okay.
> --- a/src/Kconfig
> +++ b/src/Kconfig
> @@ -387,6 +387,12 @@ menu "BIOS Tables"
>          default y
>          help
>              Support generation of ACPI tables.
> config ACPI_DSDT
>    bool "Include default ACPI DSDT"
>    default y
>    depends on ACPI
>    help
>        Include default DSDT ACPI table in BIOS.

As Paul points out, it would really help if the help stated which
released version of QEMU is needed to turn this off.
> --- a/src/acpi.c
> +++ b/src/acpi.c
> @@ -202,7 +202,11 @@ struct srat_memory_affinity
>      u32    reserved3[2];
>  } PACKED;
>
> +#ifdef CONFIG_ACPI_DSDT
>  #include "acpi-dsdt.hex"
> +#else
> +static u8 AmlCode[1];
> +#endif

As Paul points out, the #ifdef doesn't make sense as the symbol is
always defined.  However, lets avoid #ifs and let the build weed this
out.
> if (fadt && !fadt->dsdt) {
> if (fadt && !fadt->dsdt && CONFIG_ACPI_DSDT) {

It would be preferable to make the CONFIG_X be first in the if.

Thanks.
-Kevin