Document how to make SeaBIOS load and run the VGA ROM of Intel IGD device when loaded by U-Boot.
Signed-off-by: Bin Meng bmeng.cn@gmail.com ---
Changes in v2: None
doc/README.x86 | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/doc/README.x86 b/doc/README.x86 index 25cb218..250d5a3 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -807,6 +807,30 @@ to install/boot a Windows XP OS (below for example command to install Windows). This is also tested on Intel Crown Bay board with a PCIe graphics card, booting SeaBIOS then chain-loading a GRUB on a USB drive, then Linux kernel finally.
+If you are using Intel Integrated Graphics Device (IGD) as the primary display +device on your board, SeaBIOS needs to be patched manually to get its VGA ROM +loaded and run by SeaBIOS. SeaBIOS locates VGA ROM via the PCI expansion ROM +register, but IGD device does not have its VGA ROM mapped by this register. +Its VGA ROM is packaged as part of u-boot.rom at a configurable flash address +which is unknown to SeaBIOS. An example patch is needed for SeaBIOS below: + +diff --git a/src/optionroms.c b/src/optionroms.c +index 65f7fe0..c7b6f5e 100644 +--- a/src/optionroms.c ++++ b/src/optionroms.c +@@ -324,6 +324,8 @@ init_pcirom(struct pci_device *pci, int isvga, u64 *sources) + rom = deploy_romfile(file); + else if (RunPCIroms > 1 || (RunPCIroms == 1 && isvga)) + rom = map_pcirom(pci); ++ if (pci->bdf == pci_to_bdf(0, 2, 0)) ++ rom = (struct rom_header *)0xfff90000; + if (! rom) + // No ROM present. + return; + +Note: the patch above expects IGD device is at PCI b.d.f 0.2.0 and its VGA ROM +is at 0xfff90000 which corresponds to CONFIG_VGA_BIOS_ADDR on Minnowboard MAX. +Change these two accordingly if this is not the case on your board.
Development Flow ----------------