[SeaBIOS] [PATCH 3/6] paravirt: read QEMU_CFG_NOGRAPHIC, store in etc/sercon-enable romfile

[Kevin O'Connor]

On Fri, Sep 08, 2017 at 08:18:25AM +0200, Gerd Hoffmann wrote:
> Will be used as runtime switch to enable serial console support.
> 
> Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
> ---
>  src/fw/paravirt.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/fw/paravirt.c b/src/fw/paravirt.c
> index 5b23d786be..e9cca4fe6e 100644
> --- a/src/fw/paravirt.c
> +++ b/src/fw/paravirt.c
> @@ -210,6 +210,7 @@ qemu_platform_setup(void)
>  #define QEMU_CFG_SIGNATURE              0x00
>  #define QEMU_CFG_ID                     0x01
>  #define QEMU_CFG_UUID                   0x02
> +#define QEMU_CFG_NOGRAPHIC              0x04
>  #define QEMU_CFG_NUMA                   0x0d
>  #define QEMU_CFG_BOOT_MENU              0x0e
>  #define QEMU_CFG_NB_CPUS                0x05
> @@ -510,6 +511,7 @@ qemu_cfg_legacy(void)
>      qemu_romfile_add("etc/show-boot-menu", QEMU_CFG_BOOT_MENU, 0, 2);
>      qemu_romfile_add("etc/irq0-override", QEMU_CFG_IRQ0_OVERRIDE, 0, 1);
>      qemu_romfile_add("etc/max-cpus", QEMU_CFG_MAX_CPUS, 0, 2);
> +    qemu_romfile_add("etc/sercon-enable", QEMU_CFG_NOGRAPHIC, 0, 2);

Instead of looking at QEMU_CFG_NOGRAPHIC, I think the C code could
check if GET_IVT(0x10).segoff == FUNC16(entry_10).segoff .  This has
the advantage of working whenever a vgarom is not installed (including
on coreboot).

-Kevin