On Fri, 27 Jul 2018 at 19:44:28 +0200, Mark Kettenis wrote:
> > Date: Thu, 26 Jul 2018 17:56:03 -0500
> > From: joshua stein <[email protected]>
> >
> > On Thu, 26 Jul 2018 at 22:26:51 +0200, Mark Kettenis wrote:
> > > I'm hesitant to change this code. How does Linux behave on tese
> > > machines? Does it use the invisible part of the framebuffer? Or have
> > > they done away with actually using the kernel framebuffer completely
> > > like some developers threatened a couple of years ago...
> >
> > I booted a Linux USB drive and it just shows a purple/black screen
> > for a few seconds while the kernel loads until some text flashes for
> > half a second (systemd?) and then X loads. When I switch back to
> > the console, it doesn't draw off the screen. I have no idea what
> > it's doing under the hood to figure out the resolution for the
> > console.
>
> All the information about the size of the connected displays is there.
> But it is unclear to me how that information is propagated to the
> Linux kernel framebuffer code.
>
> Anyway, here is an alternative diff. This keeps the BIOS framebuffer
> but only uses the area that corresponds to the size we want. Keeping
> the BIOS framebuffer has some benefits. On many systems that
> framebuffer lives in "stolen" memory that we can't really use for any
> other purpose because the BIOS owns it. Also keeping the BIOS
> framebuffer would avoid a mode switch (at least in theory) and speed
> up the boot processes.
Works For Me (tm)
> Index: dev/pci/drm/i915/intel_fbdev.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/pci/drm/i915/intel_fbdev.c,v
> retrieving revision 1.3
> diff -u -p -r1.3 intel_fbdev.c
> --- dev/pci/drm/i915/intel_fbdev.c 1 Jul 2017 16:14:10 -0000 1.3
> +++ dev/pci/drm/i915/intel_fbdev.c 27 Jul 2018 17:26:33 -0000
> @@ -220,8 +220,10 @@ static int intelfb_create(struct drm_fb_
> } else {
> DRM_DEBUG_KMS("re-using BIOS fb\n");
> prealloc = true;
> +#ifdef __linux__
> sizes->fb_width = intel_fb->base.width;
> sizes->fb_height = intel_fb->base.height;
> +#endif
> }
>
> obj = intel_fb->obj;
>
