Hi ! So while trying to solve an issue we have with qemu/kvm and powerpc who can be both LE and BE nowadays, we thought the ideal solution would be to have a register in the emulated VGA to control the endian.
Since qemu wishes to remain as much as possible in sync / compatible with Bochs, I'm posting to this list so that the definition can be made common even if Bochs doesn't have to actually implement it. Now the basic idea is to have a bit indicating that endian control is supported and a bit to control the guest endianness, set by the guest appropriately (which affects all the pixel formats). My original idea was to add a VBE register. However BOCHS seems to be unhappy (after a quick glance at the source) if the guest tries to read a non-existing register, so I suppose either the "support endian switch" information needs to be encoded in an existing register in a way that doesn't break existing code ... or the presence of the new register advertised in such a way, for example via the PCI revision ID. Note that I am not trying to support something like endian apertures and that whole trainwreck that we had back in the day on BE machines. Simply carry the guest endianness assuming that this affects all the pixel formats which continue to be the classic ARGB ones, simply encoded with the right endian (so 8bpp is unaffected for example). Any suggestion ? Comment ? Flame ? :-) Cheers, Ben.
