Hi Laszlo [...] > > Having practically zero background in gfx development (either kernel or > Xorg), I think the problem is that vga_default_device() / > vga_set_default_device(), which -- apparently -- "boot_vga" is based > upon, come from "drivers/gpu/vga/vgaarb.c". Namely, the concept of > "primary / boot display device" is tied to the VGA arbiter, plus only a > PCI device can currently be marked as primary/boot display device. > > Can these concepts be split from each other? (I can fully imagine that > this would result in a userspace visible interface change (or > addition), > so that e.g. "/sys/devices/**/boot_gpu" would have to be consulted by > display servers.) > > (Sorry if I'm totally wrong.) > > ... Hm, reading the thread starter at > <https://www.mail-archive.com/linuxppc- > dev@xxxxxxxxxxxxxxxx/msg120851.html>, > and the references within... It looks like this work is motivated by > hardware that is supposed to be PCI, but actually breaks the specs. Is > that correct? If so, then I don't think I can suggest anything useful. My understanding is that the current PCIe HW is specs compliant but the vgaarb, in order to make a VGA device the default one, requires all the bridges on top of such device to have the "VGA Enable" bit set (optional bit in the PCI Express™ to PCI/PCI-X Bridge Spec). I.e. all the bridges on top have to support legacy VGA devices; and this is not mandatory from the specs...right? BTW my VGA experience is limited too...this is just my understanding... Gab > Specs exist so that hardware vendors and software authors follow them. > If hardware does not conform, then software should either refuse to > work > with it, or handle it with quirks, on a case-by-case basis. I guess > this > means that I don't agree with the > > broad[] suggest[ion] that a more generic solution would be better > > which seems to disqualify me from the discussion, as it must have been > suggested by people with incomparably more experience than what I have > :) > > Thanks > Laszlo
