Kevin O'Connor wrote:
On Mon, Dec 14, 2009 at 08:37:44PM -0600, Anthony Liguori wrote:
Okay, I think I've figured out how this is supposed to work. With these two patches to SeaBIOS and the patch to qemu, I can run:
I'm not sure why "Do not guard qemu shadow ram work around in CONFIG_OPTIONROMS_DEPLOYED" patch is needed. The code today is:
if (CONFIG_OPTIONROMS_DEPLOYED) { int reg = pci_config_readb(bdf, 0x5a + i); if ((reg & 0x11) != 0x11) { // Need to copy optionroms to work around qemu implementation void *mem = (void*)(BUILD_ROM_START + i * 32*1024); memcpy((void*)BUILD_BIOS_TMP_ADDR, mem, 32*1024); pci_config_writeb(bdf, 0x5a + i, 0x33); memcpy(mem, (void*)BUILD_BIOS_TMP_ADDR, 32*1024); clear = 1; } else { pci_config_writeb(bdf, 0x5a + i, 0x33); } } else { pci_config_writeb(bdf, 0x5a + i, 0x33); }So, in the non CONFIG_OPTIONROMS_DEPLOYED case, SeaBIOS will just do the write enable call (pci_config_writeb(bdf, 0x5a + i, 0x33)). The CONFIG_OPTIONROMS_DEPLOYED case should just be to copy the roms qemu has deployed. If SeaBIOS is filling in the 0xc0000-0xf0000 space, it shouldn't matter if the contents of that space is lost during the write enable.
The bios gets mapped in 0xe0000 .. 0x100000 so if SeaBIOS fills the 0xc0000-0xf0000 space it will write over half of the bios.
Regards,
Anthony Liguori