(Pulling in efifb maintainer, Peter) On Fri, 29 Apr, at 06:31:19PM, Bjorn Helgaas wrote: > > The efifb.c driver doesn't do anything at all with PCI (it includes > linux/pci.h, but probably doesn't need it). That's part of what I'm > suggesting -- if it *did* register as a PCI device driver, then it > would look at pci_dev->resource[n], which is populated by the PCI > core based on the BAR values. This discussion came up recently here, https://lkml.kernel.org/r/20160216151859.GB11373@xxxxxxxxxx There's nothing PCI-specific about the EFI framebuffer per se, but in practice it's always a PCI device. > Is ConOut what you're after? I.e., is the whole point of this > exercise to get a framebuffer driver attached to the device that was > the firmware console? I would think the ConOut path should be > decodable -- it has to tell you how to navigate the interconnect from > the CPU to the device. But I don't know how to do it. > > It looks like on x86, at least, setup_gop32()/setup_gop64() might be > extracting the framebuffer address from the ConOut device and stuffing > it into screen_info, which is what efifb.c later looks at (maybe this > is what Ard was referring to). Matthew Garrett wrote the x86 code for guessing where the console is. We look for the ConOut protocol with a fallback to first GOP device if we can't find it. I think the heuristic was based on reading the implementation in EDK2. See commit 38cb5ef4473c ("X86: Improve GOP detection in the EFI boot stub"). -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
