Oops, the FBIOPAN_DISPLAY ioctl error was a stupid mistake on mistake on
my part. Thanks for the info on where the validation code was.
Comparing against that made it easy to find the mistake. It's working
now, well...where I have been able to get over-allocation working!
Thanks for the help. If I can't get the over-allocation to work on my
other systems, I'll take it up in Intel Graphics specific channels.
While the code is a mess right now, here is a link to the program:
https://github.com/EchelonX-Ray/ttygraphics . I'm just trying to learn
about this and you really helped.
On 7/5/20 7:17 PM, Ilia Mirkin wrote:
Check fb_pan_display in drivers/video/fbdev/core/fbmem.c for the
argument validation of the FBIOPAN_DISPLAY ioctl.
CONFIG_FB_NVIDIA is a dedicated fbdev driver, not compatible with
nouveau (it takes over the relevant PCI device). It also won't support
your Pascal GPU, I believe -- I think it MIGHT support the Tesla
generation (i.e. G80..GT21x) but definitely not anything newer. Most
likely it supports pre-G80 GPUs, and again, not compatible with
nouveau.
DRM-based drivers use the DRM <-> FBDEV emulation layer to provide an
fbdev interface for legacy applications. The fbdev emulation acts as
sort of a regular DRM client and exposes the FBDEV API.
The overallocation logic was added to this emulation layer in commit
5f15257689bfa, which is included in v4.12 and later kernels.
Hope this helps,
-ilia
On Sun, Jul 5, 2020 at 7:02 PM Michael T. Kloos
<mich...@michaelkloos.com> wrote:
Well...it's been a bit of a mixed bag. Setting
drm_kms_helper.drm_fbdev_overalloc=200 set the vinfo.yres_virtual to
2160 as opposed to 1080 (My monitor vertical resolution) This fixed the
mmap() problem. However, it only worked on my main workstation. My
laptop running Intel graphics wasn't affected by the change in kernel
cmdline. My workstation is a custom build from a few years ago with a
GTX 1060 6GB, running Gentoo(Kernel version: 5.4) machine, and my laptop
running Manjaro. I also can not get the IOCTL FBIOPAN_DISPLAY to work.
It is now giving me an invalid argument error. I have set vinfo.xoffset
and vinfo.yoffset to 0 earlier in my program to try to eliminate them as
variables.
Other factors that may be at play:
-I am trying to run this from an alternate TTY. I have a graphical
environment on TTY7 with x.org. I think it is using the DRM interface.
Maybe there is a conflict.
-Maybe I am missing a driver in my Gentoo kernel config? I'm still
learning about it, but going into my workstation's kernel config, I
noticed that CONFIG_FB_NVIDIA was set to "n".
Do you know when CONFIG_DRM_FBDEV_OVERALLOC went into the kernel? I was
about to try this on my MacBook Pro running Gentoo, but I will have to
recompile upgrade the kernel before I can give a report (It is currently
running: 4.9). I couldn't find it in menuconfig so I doubt the cmdline
would make a difference.
I really appreciate the help. I've been looking header files and a such
trying to cobble together some information to figure this out. I hate
to bother you with this because it seems slightly off topic.
On 7/5/20 3:45 PM, Ilia Mirkin wrote:
Try booting with drm_kms_helper.drm_fbdev_overalloc=200 and see if it
works with that. (There's also CONFIG_DRM_FBDEV_OVERALLOC which sets
the default.)
Cheers,
-ilia
On Sun, Jul 5, 2020 at 3:41 PM <mich...@michaelkloos.com> wrote:
I am not familiar with that setting, but I have really struggled to find documentation on
dealing with the framebuffer. Referring to this guide,
"http://betteros.org/tut/graphics1.php#doublebuffer";, I attempted to set the
mmap allocation size to double, but it caused the mmap to fail. I no longer believe that
it is a driver issue, though, because I just tried it again on a dell laptop with Intel
HD Graphics 4400 to the same failure.
On Jul 5, 2020 12:35, Ilia Mirkin <imir...@alum.mit.edu> wrote:
Are you setting the overallocation to 200?
On Sun, Jul 5, 2020 at 3:41 AM Michael T. Kloos
<mich...@michaelkloos.com> wrote:
Does NOUVEAU support mmaping a double-sized Framebuffer?
When attempting to run, where fd refers to "/dev/fb0":
mmap(ptr, screensize * 2, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
I get back an invalid argument error. This doesn't happen if I only
request a single screensize. Is this a limitation of the driver?
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*Michael Thomas Kloos*
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Personal Website: http://www.michaelkloos.com/
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