| David Woodhouse | c0a2284 | 2013-02-08 15:52:01 +0000 | [diff] [blame] | 1 | Enabling CONFIG_CSM allows SeaBIOS to be built as a Compatibility Support |
| 2 | Module for use with the OMVF/EDK-II UEFI firmware. |
| 3 | |
| 4 | It will provide "legacy" BIOS services for booting non-EFI operating |
| 5 | systems and will also allow OVMF to display on otherwise unsupported |
| 6 | video hardware by using the traditional VGA BIOS. |
| 7 | |
| 8 | Windows 2008r2 is known to use INT 10h BIOS calls even when booted via |
| 9 | EFI, and the presence of a CSM makes this work as expected too. |
| 10 | |
| 11 | Having built SeaBIOS with CONFIG_CSM, you should be able to drop the |
| 12 | result into your OVMF build tree at OvmfPkg/Csm/Csm16/Csm16.bin and |
| 13 | then build OVMF with 'build -D CSM_ENABLE'. The SeaBIOS binary will be |
| 14 | included as a discrete file within the 'Flash Volume' which is |
| 15 | created, and there are tools which will extract it and allow it to be |
| 16 | replaced; satisfying the requirements of the LGPL licence. |
| 17 | |
| 18 | A patch to OVMF is required, to prevent it from marking the region from |
| 19 | 0xC0000-0xFFFFF as read-only before invoking our Legacy16Boot method. See |
| 20 | http://www.sourceforge.net/mailarchive/forum.php?thread_name=50FD7290.9060003%40redhat.com&forum_name=edk2-devel |
| 21 | |