[SeaBIOS] RFC: Primary VGA
Denis 'GNUtoo' Carikli
GNUtoo at no-log.org
Thu Feb 28 19:45:09 CET 2013
On Thu, 28 Feb 2013 08:26:54 -0700
Alex Williamson <alex.williamson at redhat.com> wrote:
> Looking at how this would happen on bare metal,
In coreboot(which can use SeaBIOS as a payload) it currently works like
that (in src/device/device.c ):
/* If we prefer plugin VGA over chipset VGA, the chipset might want to
know. */
if (!CONFIG_ONBOARD_VGA_IS_PRIMARY && (vga != vga_onboard) &&
vga_onboard && vga_onboard->ops && vga_onboard->ops->disable)
{
printk(BIOS_DEBUG, "Use plugin graphics over integrated.\n");
vga_onboard->ops->disable(vga_onboard);
}
which calls a function like that:
static void rs780_internal_gfx_disable(device_t dev)
{
u32 l_dword;
device_t nb_dev = dev_find_slot(0, 0);
/* Disable internal GFX and enable external GFX. */
l_dword = pci_read_config32(nb_dev, 0x8c);
l_dword |= 1<<0;
l_dword &= ~(1<<1);
pci_write_config32(nb_dev, 0x8c, l_dword);
dev->enabled = 0;
}
So only one card is enabled at the same time...
Denis.
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